Overhaul of glRead/DrawBuffer() code. Now, swrast->Driver.SetBuffer()

indicates the read AND draw color buffer for all software rasterization.
Lots of related clean-ups.  See RELNOTES-4.1 for details.

33 files changed, 495 insertions, 606 deletions

diff --git a/src/mesa/drivers/dos/dmesa.c b/src/mesa/drivers/dos/dmesa.c
index c9bc898dcbf..5855f04f3e7 100644
--- a/src/mesa/drivers/dos/dmesa.c
+++ b/src/mesa/drivers/dos/dmesa.c
@@ -512,8 +512,7 @@ static void clear (GLcontext *ctx, GLbitfield mask, GLboolean all,
 /*

  * Set the current reading buffer.

  */

-static void set_read_buffer (GLcontext *ctx, GLframebuffer *buffer,

-                             GLenum mode)

+static void set_buffer (GLcontext *ctx, GLframebuffer *buffer, GLenum mode)

 {

 /*

  DMesaContext c = (DMesaContext)ctx->DriverCtx;

@@ -524,18 +523,6 @@ static void set_read_buffer (GLcontext *ctx, GLframebuffer *buffer,
 

 

 /*

- * Set the destination/draw buffer.

- */

-static void set_draw_buffer (GLcontext *ctx, GLenum mode)

-{

-   /*

-     XXX this has to be fixed

-   */

-}

-

-

-

-/*

  * Return the width and height of the current buffer.

  * If anything special has to been done when the buffer/window is

  * resized, do it now.

@@ -640,6 +627,7 @@ void dmesa_init_pointers (GLcontext *ctx)
  ctx->Driver.CopyPixels = _swrast_CopyPixels;

  ctx->Driver.DrawPixels = _swrast_DrawPixels;

  ctx->Driver.ReadPixels = _swrast_ReadPixels;

+ ctx->Driver.DrawBuffer = _swrast_DrawBuffer;

 

  /* Software texture functions:

   */

@@ -671,7 +659,6 @@ void dmesa_init_pointers (GLcontext *ctx)
 

  /* Statechange callbacks:

   */

- ctx->Driver.SetDrawBuffer = set_draw_buffer;

  ctx->Driver.ClearColor = clear_color;

 

  /* Initialize the TNL driver interface:

@@ -699,7 +686,7 @@ static void dmesa_update_state (GLcontext *ctx, GLuint new_state)
  _ac_InvalidateState(ctx, new_state);

  _tnl_InvalidateState(ctx, new_state);

 

- swdd->SetReadBuffer = set_read_buffer;

+ swdd->SetBuffer = set_buffer;

 

  /* RGB(A) span/pixel functions */

  swdd->WriteRGBASpan = write_rgba_span;

diff --git a/src/mesa/drivers/ggi/ggimesa.c b/src/mesa/drivers/ggi/ggimesa.c
index 97ab159558a..86de850e915 100644
--- a/src/mesa/drivers/ggi/ggimesa.c
+++ b/src/mesa/drivers/ggi/ggimesa.c
@@ -143,50 +143,30 @@ static void gl_ggiClear(GLcontext *ctx, GLbitfield mask, GLboolean all,
 	
 }
 
-/* Set the buffer used for drawing */
-static void gl_ggiSetDrawBuffer(GLcontext *ctx, GLenum mode)
-{
-	ggi_mesa_context_t ggi_ctx = (ggi_mesa_context_t)ctx->DriverCtx;
-
-	printf("set draw %d\n", mode);
-	GGIMESADPRINT_CORE("gl_ggiSetDrawBuffer() called\n");
-	
-	if (mode == GL_FRONT_LEFT) 
-	{
-		ggiSetWriteFrame(ggi_ctx->ggi_visual,
-				 ggiGetDisplayFrame(ggi_ctx->ggi_visual));
-	}
-	else if (mode == GL_BACK_LEFT) 
-	{
-		ggiSetWriteFrame(ggi_ctx->ggi_visual,
-				 ggiGetDisplayFrame(ggi_ctx->ggi_visual)?0 : 1);
-	}
-	else 
-	{
-		/* nothing since we don't have any point/line/triangle functions. */
-	}
-}
-
 
 /* Set the buffer used for reading */
 /* XXX support for separate read/draw buffers hasn't been tested */
-static GLboolean gl_ggiSetReadBuffer(GLcontext *ctx, GLframebuffer *buffer, GLenum mode)
+static GLboolean gl_ggiSetBuffer(GLcontext *ctx, GLframebuffer *buffer, GLenum mode)
 {
 	ggi_mesa_context_t ggi_ctx = (ggi_mesa_context_t)ctx->DriverCtx;
 	
 	printf("set read %d\n", mode);
-	GGIMESADPRINT_CORE("gl_ggiSetReadBuffer() called\n");
+	GGIMESADPRINT_CORE("gl_ggiSetBuffer() called\n");
 
 	if (mode == GL_FRONT_LEFT) 
 	{
 		ggiSetReadFrame(ggi_ctx->ggi_visual,
 				ggiGetDisplayFrame(ggi_ctx->ggi_visual));
+		ggiSetWriteFrame(ggi_ctx->ggi_visual,
+				 ggiGetDisplayFrame(ggi_ctx->ggi_visual));
 		return GL_TRUE;
 	}
 	else if (mode == GL_BACK_LEFT) 
 	{
 		ggiSetReadFrame(ggi_ctx->ggi_visual,
 				ggiGetDisplayFrame(ggi_ctx->ggi_visual)?0 : 1);
+		ggiSetWriteFrame(ggi_ctx->ggi_visual,
+				 ggiGetDisplayFrame(ggi_ctx->ggi_visual)?0 : 1);
 		return GL_TRUE;
 	}
 	else
@@ -249,6 +229,7 @@ static void gl_ggiSetupPointers(GLcontext *ctx)
 	ctx->Driver.CopyPixels = _swrast_CopyPixels;
 	ctx->Driver.DrawPixels = _swrast_DrawPixels;
 	ctx->Driver.ReadPixels = _swrast_ReadPixels;
+        ctx->Driver.DrawBuffer = _swrast_DrawBuffer;
 
 	/* Software texturing */
 	ctx->Driver.ChooseTextureFormat = _mesa_choose_tex_format;
@@ -277,7 +258,6 @@ static void gl_ggiSetupPointers(GLcontext *ctx)
 	ctx->Driver.CopyConvolutionFilter2D = _swrast_CopyConvolutionFilter2D;
 	
 	/* State change callbacks */
-	ctx->Driver.SetDrawBuffer = gl_ggiSetDrawBuffer;
 	ctx->Driver.ClearIndex = gl_ggiSetClearIndex; 
 	ctx->Driver.ClearColor = gl_ggiSetClearColor;
 	ctx->Driver.IndexMask = gl_ggiIndexMask;
diff --git a/src/mesa/drivers/glide/fxdd.c b/src/mesa/drivers/glide/fxdd.c
index 2fb1a2ada4c..9b7cd306b2c 100644
--- a/src/mesa/drivers/glide/fxdd.c
+++ b/src/mesa/drivers/glide/fxdd.c
@@ -1,4 +1,4 @@
-/* $Id: fxdd.c,v 1.88 2002/06/15 03:03:10 brianp Exp $ */
+/* $Id: fxdd.c,v 1.89 2002/07/09 01:22:51 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -288,6 +288,9 @@ fxDDSetDrawBuffer(GLcontext * ctx, GLenum mode)
       /* we'll need a software fallback */
       /* XXX not implemented */
    }
+
+   /* update s/w fallback state */
+   _swrast_DrawBuffer(ctx, mode);
 }
 
 
@@ -991,7 +994,7 @@ fxSetupDDPointers(GLcontext * ctx)
    ctx->Driver.ClearIndex = NULL;
    ctx->Driver.ClearColor = fxDDClearColor;
    ctx->Driver.Clear = fxDDClear;
-   ctx->Driver.SetDrawBuffer = fxDDSetDrawBuffer;
+   ctx->Driver.DrawBuffer = fxDDSetDrawBuffer;
    ctx->Driver.GetBufferSize = fxDDBufferSize;
    ctx->Driver.Accum = _swrast_Accum;
    ctx->Driver.Bitmap = fxDDDrawBitmap;
diff --git a/src/mesa/drivers/glide/fxddspan.c b/src/mesa/drivers/glide/fxddspan.c
index 1ee7873efaf..98aabc5c0d1 100644
--- a/src/mesa/drivers/glide/fxddspan.c
+++ b/src/mesa/drivers/glide/fxddspan.c
@@ -1,4 +1,4 @@
-/* $Id: fxddspan.c,v 1.19 2001/09/23 16:50:01 brianp Exp $ */
+/* $Id: fxddspan.c,v 1.20 2002/07/09 01:22:51 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -536,7 +536,7 @@ fxDDReadDepthPixels(GLcontext * ctx, GLuint n,
 /* Set the buffer used for reading */
 /* XXX support for separate read/draw buffers hasn't been tested */
 static void
-fxDDSetReadBuffer(GLcontext * ctx, GLframebuffer * buffer, GLenum mode)
+fxDDSetBuffer(GLcontext * ctx, GLframebuffer * buffer, GLenum mode)
 {
    fxMesaContext fxMesa = (fxMesaContext) ctx->DriverCtx;
    (void) buffer;
@@ -565,7 +565,7 @@ fxSetupDDSpanPointers(GLcontext * ctx)
 {
    struct swrast_device_driver *swdd = _swrast_GetDeviceDriverReference( ctx );
 
-   swdd->SetReadBuffer = fxDDSetReadBuffer;
+   swdd->SetBuffer = fxDDSetBuffer;
 
    swdd->WriteRGBASpan = fxDDWriteRGBASpan;
    swdd->WriteRGBSpan = fxDDWriteRGBSpan;
diff --git a/src/mesa/drivers/osmesa/osmesa.c b/src/mesa/drivers/osmesa/osmesa.c
index 20847f62861..8a80ab75971 100644
--- a/src/mesa/drivers/osmesa/osmesa.c
+++ b/src/mesa/drivers/osmesa/osmesa.c
@@ -1,4 +1,4 @@
-/* $Id: osmesa.c,v 1.85 2002/06/30 16:07:18 brianp Exp $ */
+/* $Id: osmesa.c,v 1.86 2002/07/09 01:22:51 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -721,14 +721,7 @@ do {									\
 
 
 
-static void set_draw_buffer( GLcontext *ctx, GLenum mode )
-{
-   (void) ctx;
-   (void) mode;
-}
-
-
-static void set_read_buffer( GLcontext *ctx, GLframebuffer *buffer, GLenum mode )
+static void set_buffer( GLcontext *ctx, GLframebuffer *buffer, GLenum mode )
 {
    /* separate read buffer not supported */
    ASSERT(buffer == ctx->DrawBuffer);
@@ -1887,7 +1880,6 @@ static void smooth_rgba_z_triangle( GLcontext *ctx,
                                     const SWvertex *v2 )
 {
    const OSMesaContext osmesa = OSMESA_CONTEXT(ctx);
-
 #define INTERP_Z 1
 #define DEPTH_TYPE DEFAULT_SOFTWARE_DEPTH_TYPE
 #define INTERP_RGB 1
@@ -1903,7 +1895,7 @@ static void smooth_rgba_z_triangle( GLcontext *ctx,
             FixedToChan(span->alpha));				\
          zRow[i] = z;						\
       }								\
-      span->red += span->redStep;					\
+      span->red += span->redStep;				\
       span->green += span->greenStep;				\
       span->blue += span->blueStep;				\
       span->alpha += span->alphaStep;				\
@@ -2080,7 +2072,6 @@ static void osmesa_update_state( GLcontext *ctx, GLuint new_state )
 
    ctx->Driver.GetString = get_string;
    ctx->Driver.UpdateState = osmesa_update_state;
-   ctx->Driver.SetDrawBuffer = set_draw_buffer;
    ctx->Driver.ResizeBuffers = _swrast_alloc_buffers;
    ctx->Driver.GetBufferSize = buffer_size;
 
@@ -2090,6 +2081,7 @@ static void osmesa_update_state( GLcontext *ctx, GLuint new_state )
    ctx->Driver.CopyPixels = _swrast_CopyPixels;
    ctx->Driver.DrawPixels = _swrast_DrawPixels;
    ctx->Driver.ReadPixels = _swrast_ReadPixels;
+   ctx->Driver.DrawBuffer = _swrast_DrawBuffer;
 
    ctx->Driver.ChooseTextureFormat = _mesa_choose_tex_format;
    ctx->Driver.TexImage1D = _mesa_store_teximage1d;
@@ -2114,6 +2106,8 @@ static void osmesa_update_state( GLcontext *ctx, GLuint new_state )
    ctx->Driver.CompressedTextureSize = _mesa_compressed_texture_size;
    ctx->Driver.GetCompressedTexImage = _mesa_get_compressed_teximage;
 
+   swdd->SetBuffer = set_buffer;
+
    /* RGB(A) span/pixel functions */
    if (osmesa->format == OSMESA_RGB) {
       swdd->WriteRGBASpan = write_rgba_span_RGB;
@@ -2171,8 +2165,6 @@ static void osmesa_update_state( GLcontext *ctx, GLuint new_state )
    swdd->ReadCI32Span = read_index_span;
    swdd->ReadCI32Pixels = read_index_pixels;
 
-   swdd->SetReadBuffer = set_read_buffer;
-
    tnl->Driver.RunPipeline = _tnl_run_pipeline;
 
    _swrast_InvalidateState( ctx, new_state );
diff --git a/src/mesa/drivers/svga/svgamesa.c b/src/mesa/drivers/svga/svgamesa.c
index 5d2e3d55a23..270455ee691 100644
--- a/src/mesa/drivers/svga/svgamesa.c
+++ b/src/mesa/drivers/svga/svgamesa.c
@@ -1,4 +1,4 @@
-/* $Id: svgamesa.c,v 1.19 2002/06/15 02:38:17 brianp Exp $ */
+/* $Id: svgamesa.c,v 1.20 2002/07/09 01:22:51 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -217,34 +217,9 @@ static void get_buffer_size( GLframebuffer *buffer, GLuint *width, GLuint *heigh
    *height = SVGAMesa->height = vga_getydim();
 }
 
-static void set_draw_buffer( GLcontext *ctx, GLenum buffer )
-{
-   if (buffer == GL_FRONT_LEFT) {
-      SVGABuffer.DrawBuffer = SVGABuffer.FrontBuffer;
-#if 0
-      /*    vga_waitretrace(); */
-      void * tmpptr;
-      copy_buffer(SVGABuffer.FrontBuffer);
-      tmpptr=SVGABuffer.BackBuffer;
-      SVGABuffer.BackBuffer=SVGABuffer.FrontBuffer;
-      SVGABuffer.FrontBuffer=tmpptr;
-#endif
-   }
-   else if (buffer == GL_BACK_LEFT) {
-      SVGABuffer.DrawBuffer = SVGABuffer.BackBuffer;
-#if 0
-      /*    vga_waitretrace(); */
-      copy_buffer(SVGABuffer.BackBuffer);
-#endif
-   }
-   else {
-      /* nothing since we don't have any point/line/triangle functions. */
-   }
-}
 
-
-static void set_read_buffer( GLcontext *ctx, GLframebuffer *colorBuffer,
-                             GLenum buffer )
+static void set_buffer( GLcontext *ctx, GLframebuffer *colorBuffer,
+                        GLenum buffer )
 {
    /* We can ignore colorBuffer since we don't support a MakeCurrentRead()
     * function.
@@ -253,6 +228,7 @@ static void set_read_buffer( GLcontext *ctx, GLframebuffer *colorBuffer,
 
    if (buffer == GL_FRONT_LEFT) {
       SVGABuffer.ReadBuffer = SVGABuffer.FrontBuffer;
+      SVGABuffer.DrawBuffer = SVGABuffer.FrontBuffer;
 #if 0
       void * tmpptr;
       /*    vga_waitretrace(); */
@@ -264,6 +240,7 @@ static void set_read_buffer( GLcontext *ctx, GLframebuffer *colorBuffer,
    }
    else if (buffer == GL_BACK_LEFT) {
       SVGABuffer.ReadBuffer = SVGABuffer.BackBuffer;
+      SVGABuffer.DrawBuffer = SVGABuffer.BackBuffer;
 #if 0
       /*    vga_waitretrace(); */
       copy_buffer(SVGABuffer.BackBuffer);
@@ -285,7 +262,6 @@ static void svgamesa_update_state( GLcontext *ctx, GLuint new_state )
    ctx->Driver.UpdateState = svgamesa_update_state;
 
    ctx->Driver.GetBufferSize = get_buffer_size;
-   ctx->Driver.SetDrawBuffer = set_draw_buffer;
    ctx->Driver.ResizeBuffers = _swrast_alloc_buffers;
 
    /* Software rasterizer pixel paths:
@@ -295,10 +271,11 @@ static void svgamesa_update_state( GLcontext *ctx, GLuint new_state )
    ctx->Driver.CopyPixels = _swrast_CopyPixels;
    ctx->Driver.DrawPixels = _swrast_DrawPixels;
    ctx->Driver.ReadPixels = _swrast_ReadPixels;
+   ctx->Driver.DrawBuffer = _swrast_DrawBuffer;
 
    /* Fill in the swrast driver interface:
     */
-   swdd->SetReadBuffer = set_read_buffer;
+   swdd->SetBuffer = set_buffer;
 
    switch (SVGABuffer.Depth) {
     case  8: ctx->Driver.ClearIndex = __clear_index8;
diff --git a/src/mesa/drivers/windows/wmesa.c b/src/mesa/drivers/windows/wmesa.c
index 09fa23737f9..35a670096aa 100644
--- a/src/mesa/drivers/windows/wmesa.c
+++ b/src/mesa/drivers/windows/wmesa.c
@@ -1,4 +1,4 @@
-/* $Id: wmesa.c,v 1.31 2002/06/15 03:03:10 brianp Exp $ */
+/* $Id: wmesa.c,v 1.32 2002/07/09 01:22:51 brianp Exp $ */
 
 /*
  * Windows (Win32) device driver for Mesa 3.4
@@ -569,20 +569,12 @@ static void enable( GLcontext* ctx, GLenum pname, GLboolean enable )
   }
 }
 
-static void set_draw_buffer( GLcontext* ctx, GLenum mode )
-{
-   /* XXX doing nothing for now */
-   /* if front buffer, fine */
-   /* if back buffer, fine */
-   /* else, check swrast->_RasterMask & MULTI_DRAW_BIT, if true, */
-   /* use a swrast fallback function */
-}
 
 
-static void set_read_buffer(GLcontext *ctx, GLframebuffer *colorBuffer,
-                            GLenum buffer )
+static void set_buffer(GLcontext *ctx, GLframebuffer *colorBuffer,
+                       GLenum buffer )
 {
-  /* XXX todo */
+  /* XXX todo - examine buffer and set read/write pointers */
   return;
 }
 
@@ -1027,7 +1019,6 @@ static void SetFunctionPointers(GLcontext *ctx)
   struct swrast_device_driver *swdd = _swrast_GetDeviceDriverReference( ctx );
   ctx->Driver.GetString = get_string;
   ctx->Driver.UpdateState = wmesa_update_state;
-  ctx->Driver.SetDrawBuffer = set_draw_buffer;
   ctx->Driver.ResizeBuffers = _swrast_alloc_buffers;
   ctx->Driver.GetBufferSize = buffer_size;
   
@@ -1043,6 +1034,7 @@ static void SetFunctionPointers(GLcontext *ctx)
   ctx->Driver.CopyPixels = _swrast_CopyPixels;
   ctx->Driver.DrawPixels = _swrast_DrawPixels;
   ctx->Driver.ReadPixels = _swrast_ReadPixels;
+  ctx->Driver.DrawBuffer = _swrast_DrawBuffer;
   
   ctx->Driver.ChooseTextureFormat = _mesa_choose_tex_format;
   ctx->Driver.TexImage1D = _mesa_store_teximage1d;
@@ -1068,7 +1060,7 @@ static void SetFunctionPointers(GLcontext *ctx)
   ctx->Driver.GetCompressedTexImage = _mesa_get_compressed_teximage;
   
   
-  swdd->SetReadBuffer = set_read_buffer;
+  swdd->SetBuffer = set_buffer;
   
   
   /* Pixel/span writing functions: */
@@ -1106,7 +1098,6 @@ static void wmesa_update_state( GLcontext *ctx, GLuint new_state )
 #if 0
   ctx->Driver.GetString = get_string;
   ctx->Driver.UpdateState = wmesa_update_state;
-  ctx->Driver.SetDrawBuffer = set_draw_buffer;
   ctx->Driver.ResizeBuffers = _swrast_alloc_buffers;
   ctx->Driver.GetBufferSize = buffer_size;
   
@@ -1145,10 +1136,8 @@ static void wmesa_update_state( GLcontext *ctx, GLuint new_state )
   ctx->Driver.BaseCompressedTexFormat = _mesa_base_compressed_texformat;
   ctx->Driver.CompressedTextureSize = _mesa_compressed_texture_size;
   ctx->Driver.GetCompressedTexImage = _mesa_get_compressed_teximage;
-  
-  
-  swdd->SetReadBuffer = set_read_buffer;
-  
+    
+  swdd->SetBuffer = set_buffer;
   
   /* Pixel/span writing functions: */
   swdd->WriteRGBASpan        = write_rgba_span;
diff --git a/src/mesa/drivers/x11/xm_api.c b/src/mesa/drivers/x11/xm_api.c
index 1ef83c12cfe..4d74281bf92 100644
--- a/src/mesa/drivers/x11/xm_api.c
+++ b/src/mesa/drivers/x11/xm_api.c
@@ -1,4 +1,4 @@
-/* $Id: xm_api.c,v 1.39 2002/06/17 23:38:14 brianp Exp $ */
+/* $Id: xm_api.c,v 1.40 2002/07/09 01:22:51 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -1654,6 +1654,8 @@ XMesaContext XMesaCreateContext( XMesaVisual v, XMesaContext share_list )
    }
 
    c->xm_visual = v;
+   c->xm_draw_buffer = NULL;   /* set later by XMesaMakeCurrent */
+   c->xm_read_buffer = NULL;   /* set later by XMesaMakeCurrent */
    c->xm_buffer = NULL;   /* set later by XMesaMakeCurrent */
    c->display = v->display;
    c->pixelformat = v->dithered_pf;      /* Dithering is enabled by default */
@@ -1682,8 +1684,8 @@ XMesaContext XMesaCreateContext( XMesaVisual v, XMesaContext share_list )
 void XMesaDestroyContext( XMesaContext c )
 {
 #ifdef FX
-   if (c->xm_buffer && c->xm_buffer->FXctx)
-      fxMesaDestroyContext(c->xm_buffer->FXctx);
+   if (c->xm_draw_buffer && c->xm_buffer->FXctx)
+      fxMesaDestroyContext(c->xm_draw_buffer->FXctx);
 #endif
    if (c->gl_ctx) {
       _swsetup_DestroyContext( c->gl_ctx );
@@ -2045,24 +2047,24 @@ GLboolean XMesaMakeCurrent2( XMesaContext c, XMesaBuffer drawBuffer,
       if (drawBuffer->FXctx) {
          fxMesaMakeCurrent(drawBuffer->FXctx);
 
-         c->xm_buffer = drawBuffer;
+         c->xm_draw_buffer = drawBuffer;
          c->xm_read_buffer = readBuffer;
-         c->use_read_buffer = (drawBuffer != readBuffer);
+         c->xm_buffer = drawBuffer;
 
          return GL_TRUE;
       }
 #endif
       if (c->gl_ctx == _mesa_get_current_context()
-          && c->xm_buffer == drawBuffer
+          && c->xm_draw_buffer == drawBuffer
           && c->xm_read_buffer == readBuffer
-          && c->xm_buffer->wasCurrent) {
+          && c->xm_draw_buffer->wasCurrent) {
          /* same context and buffer, do nothing */
          return GL_TRUE;
       }
 
-      c->xm_buffer = drawBuffer;
+      c->xm_draw_buffer = drawBuffer;
       c->xm_read_buffer = readBuffer;
-      c->use_read_buffer = (drawBuffer != readBuffer);
+      c->xm_buffer = drawBuffer;
 
       _mesa_make_current2(c->gl_ctx,
                           &drawBuffer->mesa_buffer,
@@ -2086,11 +2088,11 @@ GLboolean XMesaMakeCurrent2( XMesaContext c, XMesaBuffer drawBuffer,
                                                c->clearcolor[2],
                                                c->clearcolor[3],
                                                c->xm_visual->undithered_pf);
-         XMesaSetForeground(c->display, c->xm_buffer->cleargc, c->clearpixel);
+         XMesaSetForeground(c->display, c->xm_draw_buffer->cleargc, c->clearpixel);
       }
 
       /* Solution to Stephane Rehel's problem with glXReleaseBuffersMESA(): */
-      c->xm_buffer->wasCurrent = GL_TRUE;
+      c->xm_draw_buffer->wasCurrent = GL_TRUE;
    }
    else {
       /* Detach */
@@ -2128,7 +2130,7 @@ XMesaBuffer XMesaGetCurrentBuffer( void )
    GET_CURRENT_CONTEXT(ctx);
    if (ctx) {
       XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
-      return xmesa->xm_buffer;
+      return xmesa->xm_draw_buffer;
    }
    else {
       return 0;
@@ -2142,7 +2144,7 @@ XMesaBuffer XMesaGetCurrentReadBuffer( void )
    GET_CURRENT_CONTEXT(ctx);
    if (ctx) {
       XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
-      return xmesa->xm_buffer;
+      return xmesa->xm_read_buffer;
    }
    else {
       return 0;
@@ -2154,7 +2156,7 @@ GLboolean XMesaForceCurrent(XMesaContext c)
 {
    if (c) {
       if (c->gl_ctx != _mesa_get_current_context()) {
-	 _mesa_make_current(c->gl_ctx, &c->xm_buffer->mesa_buffer);
+	 _mesa_make_current(c->gl_ctx, &c->xm_draw_buffer->mesa_buffer);
       }
    }
    else {
@@ -2193,15 +2195,15 @@ GLboolean XMesaSetFXmode( GLint mode )
       if (ctx) {
          XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
          if (mode == XMESA_FX_WINDOW) {
-	    if (xmesa->xm_buffer->FXisHackUsable) {
+	    if (xmesa->xm_draw_buffer->FXisHackUsable) {
 	       FX_grSstControl(GR_CONTROL_DEACTIVATE);
-	       xmesa->xm_buffer->FXwindowHack = GL_TRUE;
+	       xmesa->xm_draw_buffer->FXwindowHack = GL_TRUE;
 	       return GL_TRUE;
 	    }
 	 }
 	 else if (mode == XMESA_FX_FULLSCREEN) {
 	    FX_grSstControl(GR_CONTROL_ACTIVATE);
-	    xmesa->xm_buffer->FXwindowHack = GL_FALSE;
+	    xmesa->xm_draw_buffer->FXwindowHack = GL_FALSE;
 	    return GL_TRUE;
 	 }
 	 else {
@@ -2232,7 +2234,7 @@ static void FXgetImage( XMesaBuffer b )
    unsigned int bw, depth, width, height;
    XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
 
-   assert(xmesa->xm_buffer->FXctx);
+   assert(xmesa->xm_draw_buffer->FXctx);
 
 #ifdef XFree86Server
    x = b->frontbuffer->x;
@@ -2245,8 +2247,8 @@ static void FXgetImage( XMesaBuffer b )
                  &root, &xpos, &ypos, &width, &height, &bw, &depth);
 #endif
    if (b->width != width || b->height != height) {
-      b->width = MIN2((int)width, xmesa->xm_buffer->FXctx->width);
-      b->height = MIN2((int)height, xmesa->xm_buffer->FXctx->height);
+      b->width = MIN2((int)width, xmesa->xm_draw_buffer->FXctx->width);
+      b->height = MIN2((int)height, xmesa->xm_draw_buffer->FXctx->height);
       if (b->width & 1)
          b->width--;  /* prevent odd width */
       xmesa_alloc_back_buffer( b );
@@ -2256,7 +2258,7 @@ static void FXgetImage( XMesaBuffer b )
    if (xmesa->xm_visual->undithered_pf==PF_5R6G5B) {
       /* Special case: 16bpp RGB */
       grLfbReadRegion( GR_BUFFER_FRONTBUFFER,       /* src buffer */
-                       0, xmesa->xm_buffer->FXctx->height - b->height,  /*pos*/
+                       0, xmesa->xm_draw_buffer->FXctx->height - b->height,  /*pos*/
                        b->width, b->height,         /* size */
                        b->width * sizeof(GLushort), /* stride */
                        b->backimage->data);         /* dest buffer */
@@ -2265,13 +2267,13 @@ static void FXgetImage( XMesaBuffer b )
 	    && GET_VISUAL_DEPTH(xmesa->xm_visual)==8) {
       /* Special case: 8bpp RGB */
       for (y=0;y<b->height;y++) {
-         GLubyte *ptr = (GLubyte*) xmesa->xm_buffer->backimage->data
-                        + xmesa->xm_buffer->backimage->bytes_per_line * y;
+         GLubyte *ptr = (GLubyte*) xmesa->xm_draw_buffer->backimage->data
+                        + xmesa->xm_draw_buffer->backimage->bytes_per_line * y;
          XDITHER_SETUP(y);
 
          /* read row from 3Dfx frame buffer */
          grLfbReadRegion( GR_BUFFER_FRONTBUFFER,
-                          0, xmesa->xm_buffer->FXctx->height-(b->height-y),
+                          0, xmesa->xm_draw_buffer->FXctx->height-(b->height-y),
                           b->width, 1,
                           0,
                           pixbuf );
@@ -2290,7 +2292,7 @@ static void FXgetImage( XMesaBuffer b )
       for (y=0;y<b->height;y++) {
          /* read row from 3Dfx frame buffer */
          grLfbReadRegion( GR_BUFFER_FRONTBUFFER,
-                          0, xmesa->xm_buffer->FXctx->height-(b->height-y),
+                          0, xmesa->xm_draw_buffer->FXctx->height-(b->height-y),
                           b->width, 1,
                           0,
                           pixbuf );
diff --git a/src/mesa/drivers/x11/xm_dd.c b/src/mesa/drivers/x11/xm_dd.c
index c10afede922..8aa10ae8057 100644
--- a/src/mesa/drivers/x11/xm_dd.c
+++ b/src/mesa/drivers/x11/xm_dd.c
@@ -1,4 +1,4 @@
-/* $Id: xm_dd.c,v 1.33 2002/06/19 21:49:37 brianp Exp $ */
+/* $Id: xm_dd.c,v 1.34 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -116,74 +116,51 @@ flush( GLcontext *ctx )
 }
 
 
-static void
-set_draw_buffer( GLcontext *ctx, GLenum mode )
-{
-   const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
-   if (mode == GL_FRONT_LEFT) {
-      /* write to front buffer */
-      xmesa->xm_buffer->buffer = xmesa->xm_buffer->frontbuffer;
-      xmesa_update_span_funcs(ctx);
-   }
-   else if (mode==GL_BACK_LEFT && xmesa->xm_buffer->db_state) {
-      /* write to back buffer */
-      if (xmesa->xm_buffer->backpixmap) {
-         xmesa->xm_buffer->buffer =
-	     (XMesaDrawable)xmesa->xm_buffer->backpixmap;
-      }
-      else if (xmesa->xm_buffer->backimage) {
-         xmesa->xm_buffer->buffer = None;
-      }
-      else {
-         /* just in case there wasn't enough memory for back buffer */
-         xmesa->xm_buffer->buffer = xmesa->xm_buffer->frontbuffer;
-      }
-      xmesa_update_span_funcs(ctx);
-   }
-   else {
-      /* the swrast->_RasterMask MULTI_DRAW_BIT will be set and
-       * we'll fall back to swrast to draw points/lines/triangles.
-       */
-   }
-}
 
-
-void
-xmesa_set_read_buffer( GLcontext *ctx, GLframebuffer *buffer, GLenum mode )
+/*
+ * This chooses the color buffer for reading and writing spans, points,
+ * lines, and triangles.
+ */
+static void
+set_buffer( GLcontext *ctx, GLframebuffer *buffer, GLenum mode )
 {
-   XMesaBuffer target;
+   /* We can make this cast since the XMesaBuffer wraps GLframebuffer.
+    * GLframebuffer is the first member in a XMesaBuffer struct.
+    */
+   XMesaBuffer target = (XMesaBuffer) buffer;
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
 
-   if (buffer == ctx->DrawBuffer) {
-      target = xmesa->xm_buffer;
-      xmesa->use_read_buffer = GL_FALSE;
-   }
-   else {
-      ASSERT(buffer == ctx->ReadBuffer);
-      target = xmesa->xm_read_buffer;
-      xmesa->use_read_buffer = GL_TRUE;
-   }
+   /* This assignment tells the span/point/line/triangle functions
+    * which XMesaBuffer to use.
+    */
+   xmesa->xm_buffer = target;
 
+   /*
+    * Now determine front vs back color buffer.
+    */
    if (mode == GL_FRONT_LEFT) {
       target->buffer = target->frontbuffer;
-      xmesa_update_span_funcs(ctx);
    }
-   else if (mode==GL_BACK_LEFT && xmesa->xm_read_buffer->db_state) {
+   else if (mode == GL_BACK_LEFT) {
+      ASSERT(target->db_state);
       if (target->backpixmap) {
-         target->buffer = (XMesaDrawable)xmesa->xm_buffer->backpixmap;
+         /* back buffer is a pixmape */
+         target->buffer = target->backpixmap;
       }
       else if (target->backimage) {
+         /* back buffer is an XImage */
          target->buffer = None;
       }
       else {
-         /* just in case there wasn't enough memory for back buffer */
+         /* No back buffer!!!!  Must be out of memory, use front buffer */
          target->buffer = target->frontbuffer;
       }
-      xmesa_update_span_funcs(ctx);
    }
    else {
-      _mesa_problem(ctx, "invalid buffer in set_read_buffer() in xmesa2.c");
+      _mesa_problem(ctx, "invalid buffer in set_buffer() in xmesa2.c");
+      return;
    }
+   xmesa_update_span_funcs(ctx);
 }
 
 
@@ -193,7 +170,7 @@ clear_index( GLcontext *ctx, GLuint index )
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
    xmesa->clearpixel = (unsigned long) index;
-   XMesaSetForeground( xmesa->display, xmesa->xm_buffer->cleargc,
+   XMesaSetForeground( xmesa->display, xmesa->xm_draw_buffer->cleargc,
                        (unsigned long) index );
 }
 
@@ -210,7 +187,7 @@ clear_color( GLcontext *ctx, const GLchan color[4] )
                                              color[2], color[3],
                                              xmesa->xm_visual->undithered_pf );
    _glthread_LOCK_MUTEX(_xmesa_lock);
-   XMesaSetForeground( xmesa->display, xmesa->xm_buffer->cleargc,
+   XMesaSetForeground( xmesa->display, xmesa->xm_draw_buffer->cleargc,
                        xmesa->clearpixel );
    _glthread_UNLOCK_MUTEX(_xmesa_lock);
 }
@@ -222,7 +199,7 @@ static void
 index_mask( GLcontext *ctx, GLuint mask )
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
-   if (xmesa->xm_buffer->buffer != XIMAGE) {
+   if (xmesa->xm_draw_buffer->buffer != XIMAGE) {
       unsigned long m;
       if (mask==0xffffffff) {
 	 m = ((unsigned long)~0L);
@@ -230,7 +207,7 @@ index_mask( GLcontext *ctx, GLuint mask )
       else {
          m = (unsigned long) mask;
       }
-      XMesaSetPlaneMask( xmesa->display, xmesa->xm_buffer->cleargc, m );
+      XMesaSetPlaneMask( xmesa->display, xmesa->xm_draw_buffer->cleargc, m );
    }
 }
 
@@ -255,7 +232,7 @@ color_mask(GLcontext *ctx,
          if (gmask)   m |= GET_GREENMASK(xmesa->xm_visual);
          if (bmask)   m |= GET_BLUEMASK(xmesa->xm_visual);
       }
-      XMesaSetPlaneMask( xmesa->display, xmesa->xm_buffer->cleargc, m );
+      XMesaSetPlaneMask( xmesa->display, xmesa->xm_draw_buffer->cleargc, m );
    }
 }
 
@@ -272,16 +249,16 @@ clear_front_pixmap( GLcontext *ctx, GLboolean all,
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
    if (all) {
-      XMesaFillRectangle( xmesa->display, xmesa->xm_buffer->frontbuffer,
-                          xmesa->xm_buffer->cleargc,
+      XMesaFillRectangle( xmesa->display, xmesa->xm_draw_buffer->frontbuffer,
+                          xmesa->xm_draw_buffer->cleargc,
                           0, 0,
-                          xmesa->xm_buffer->width+1,
-                          xmesa->xm_buffer->height+1 );
+                          xmesa->xm_draw_buffer->width+1,
+                          xmesa->xm_draw_buffer->height+1 );
    }
    else {
-      XMesaFillRectangle( xmesa->display, xmesa->xm_buffer->frontbuffer,
-                          xmesa->xm_buffer->cleargc,
-                          x, xmesa->xm_buffer->height - y - height,
+      XMesaFillRectangle( xmesa->display, xmesa->xm_draw_buffer->frontbuffer,
+                          xmesa->xm_draw_buffer->cleargc,
+                          x, xmesa->xm_draw_buffer->height - y - height,
                           width, height );
    }
 }
@@ -293,16 +270,16 @@ clear_back_pixmap( GLcontext *ctx, GLboolean all,
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
    if (all) {
-      XMesaFillRectangle( xmesa->display, xmesa->xm_buffer->backpixmap,
-                          xmesa->xm_buffer->cleargc,
+      XMesaFillRectangle( xmesa->display, xmesa->xm_draw_buffer->backpixmap,
+                          xmesa->xm_draw_buffer->cleargc,
                           0, 0,
-                          xmesa->xm_buffer->width+1,
-                          xmesa->xm_buffer->height+1 );
+                          xmesa->xm_draw_buffer->width+1,
+                          xmesa->xm_draw_buffer->height+1 );
    }
    else {
-      XMesaFillRectangle( xmesa->display, xmesa->xm_buffer->backpixmap,
-                          xmesa->xm_buffer->cleargc,
-                          x, xmesa->xm_buffer->height - y - height,
+      XMesaFillRectangle( xmesa->display, xmesa->xm_draw_buffer->backpixmap,
+                          xmesa->xm_draw_buffer->cleargc,
+                          x, xmesa->xm_draw_buffer->height - y - height,
                           width, height );
    }
 }
@@ -314,14 +291,14 @@ clear_8bit_ximage( GLcontext *ctx, GLboolean all,
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
    if (all) {
-      size_t n = xmesa->xm_buffer->backimage->bytes_per_line
-         * xmesa->xm_buffer->backimage->height;
-      MEMSET( xmesa->xm_buffer->backimage->data, xmesa->clearpixel, n );
+      size_t n = xmesa->xm_draw_buffer->backimage->bytes_per_line
+         * xmesa->xm_draw_buffer->backimage->height;
+      MEMSET( xmesa->xm_draw_buffer->backimage->data, xmesa->clearpixel, n );
    }
    else {
       GLint i;
       for (i=0;i<height;i++) {
-         GLubyte *ptr = PIXELADDR1( xmesa->xm_buffer, x, y+i );
+         GLubyte *ptr = PIXELADDR1( xmesa->xm_draw_buffer, x, y+i );
          MEMSET( ptr, xmesa->clearpixel, width );
       }
    }
@@ -334,9 +311,9 @@ clear_HPCR_ximage( GLcontext *ctx, GLboolean all,
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
    if (all) {
-      GLint i, c16 = (xmesa->xm_buffer->backimage->bytes_per_line>>4)<<4;
-      GLubyte *ptr  = (GLubyte *)xmesa->xm_buffer->backimage->data;
-      for (i=0; i<xmesa->xm_buffer->backimage->height; i++) {
+      GLint i, c16 = (xmesa->xm_draw_buffer->backimage->bytes_per_line>>4)<<4;
+      GLubyte *ptr  = (GLubyte *)xmesa->xm_draw_buffer->backimage->data;
+      for (i=0; i<xmesa->xm_draw_buffer->backimage->height; i++) {
          GLint j;
          GLubyte *sptr = xmesa->xm_visual->hpcr_clear_ximage_pattern[0];
          if (i&1) {
@@ -361,7 +338,7 @@ clear_HPCR_ximage( GLcontext *ctx, GLboolean all,
             ptr[15] = sptr[15];
             ptr += 16;
          }
-         for (; j<xmesa->xm_buffer->backimage->bytes_per_line; j++) {
+         for (; j<xmesa->xm_draw_buffer->backimage->bytes_per_line; j++) {
             *ptr = sptr[j&15];
             ptr++;
          }
@@ -370,7 +347,7 @@ clear_HPCR_ximage( GLcontext *ctx, GLboolean all,
    else {
       GLint i;
       for (i=y; i<y+height; i++) {
-         GLubyte *ptr = PIXELADDR1( xmesa->xm_buffer, x, i );
+         GLubyte *ptr = PIXELADDR1( xmesa->xm_draw_buffer, x, i );
          int j;
          GLubyte *sptr = xmesa->xm_visual->hpcr_clear_ximage_pattern[0];
          if (i&1) {
@@ -396,31 +373,31 @@ clear_16bit_ximage( GLcontext *ctx, GLboolean all,
    }
    if (all) {
       register GLuint n;
-      register GLuint *ptr4 = (GLuint *) xmesa->xm_buffer->backimage->data;
+      register GLuint *ptr4 = (GLuint *) xmesa->xm_draw_buffer->backimage->data;
       if ((pixel & 0xff) == ((pixel >> 8) & 0xff)) {
          /* low and high bytes are equal so use memset() */
-         n = xmesa->xm_buffer->backimage->bytes_per_line
-            * xmesa->xm_buffer->height;
+         n = xmesa->xm_draw_buffer->backimage->bytes_per_line
+            * xmesa->xm_draw_buffer->height;
          MEMSET( ptr4, pixel & 0xff, n );
       }
       else {
          pixel = pixel | (pixel<<16);
-         n = xmesa->xm_buffer->backimage->bytes_per_line
-            * xmesa->xm_buffer->height / 4;
+         n = xmesa->xm_draw_buffer->backimage->bytes_per_line
+            * xmesa->xm_draw_buffer->height / 4;
          do {
             *ptr4++ = pixel;
                n--;
          } while (n!=0);
 
-         if ((xmesa->xm_buffer->backimage->bytes_per_line *
-              xmesa->xm_buffer->height) & 0x2)
+         if ((xmesa->xm_draw_buffer->backimage->bytes_per_line *
+              xmesa->xm_draw_buffer->height) & 0x2)
             *(GLushort *)ptr4 = pixel & 0xffff;
       }
    }
    else {
       register int i, j;
       for (j=0;j<height;j++) {
-         register GLushort *ptr2 = PIXELADDR2( xmesa->xm_buffer, x, y+j );
+         register GLushort *ptr2 = PIXELADDR2( xmesa->xm_draw_buffer, x, y+j );
          for (i=0;i<width;i++) {
             *ptr2++ = pixel;
          }
@@ -449,21 +426,21 @@ clear_24bit_ximage( GLcontext *ctx, GLboolean all,
    if (all) {
       if (r==g && g==b) {
          /* same value for all three components (gray) */
-         const GLint w3 = xmesa->xm_buffer->width * 3;
-         const GLint h = xmesa->xm_buffer->height;
+         const GLint w3 = xmesa->xm_draw_buffer->width * 3;
+         const GLint h = xmesa->xm_draw_buffer->height;
          GLint i;
          for (i = 0; i < h; i++) {
-            bgr_t *ptr3 = PIXELADDR3(xmesa->xm_buffer, 0, i);
+            bgr_t *ptr3 = PIXELADDR3(xmesa->xm_draw_buffer, 0, i);
             MEMSET(ptr3, r, w3);
          }
       }
       else {
          /* the usual case */
-         const GLint w = xmesa->xm_buffer->width;
-         const GLint h = xmesa->xm_buffer->height;
+         const GLint w = xmesa->xm_draw_buffer->width;
+         const GLint h = xmesa->xm_draw_buffer->height;
          GLint i, j;
          for (i = 0; i < h; i++) {
-            bgr_t *ptr3 = PIXELADDR3(xmesa->xm_buffer, 0, i);
+            bgr_t *ptr3 = PIXELADDR3(xmesa->xm_draw_buffer, 0, i);
             for (j = 0; j < w; j++) {
                ptr3->r = r;
                ptr3->g = g;
@@ -547,7 +524,7 @@ clear_24bit_ximage( GLcontext *ctx, GLboolean all,
          /* same value for all three components (gray) */
          GLint j;
          for (j=0;j<height;j++) {
-            bgr_t *ptr3 = PIXELADDR3( xmesa->xm_buffer, x, y+j );
+            bgr_t *ptr3 = PIXELADDR3( xmesa->xm_draw_buffer, x, y+j );
             MEMSET(ptr3, r, 3 * width);
          }
       }
@@ -555,7 +532,7 @@ clear_24bit_ximage( GLcontext *ctx, GLboolean all,
          /* non-gray clear color */
          GLint i, j;
          for (j = 0; j < height; j++) {
-            bgr_t *ptr3 = PIXELADDR3( xmesa->xm_buffer, x, y+j );
+            bgr_t *ptr3 = PIXELADDR3( xmesa->xm_draw_buffer, x, y+j );
             for (i = 0; i < width; i++) {
                ptr3->r = r;
                ptr3->g = g;
@@ -570,7 +547,7 @@ clear_24bit_ximage( GLcontext *ctx, GLboolean all,
          pixel4[1] = (clearPixel << 16) | (clearPixel >> 8);
          pixel4[2] = (clearPixel << 8) | (clearPixel >>  16);
          for (j=0;j<height;j++) {
-            bgr_t *ptr3 = PIXELADDR3( xmesa->xm_buffer, x, y+j );
+            bgr_t *ptr3 = PIXELADDR3( xmesa->xm_draw_buffer, x, y+j );
             register GLuint *ptr4 = (GLuint *)ptr3;
             register GLuint *p, px;
             GLuint w = width;
@@ -653,8 +630,8 @@ clear_32bit_ximage( GLcontext *ctx, GLboolean all,
             | ((pixel << 24) & 0xff000000);
    }
    if (all) {
-      register GLint n = xmesa->xm_buffer->width * xmesa->xm_buffer->height;
-      register GLuint *ptr4 = (GLuint *) xmesa->xm_buffer->backimage->data;
+      register GLint n = xmesa->xm_draw_buffer->width * xmesa->xm_draw_buffer->height;
+      register GLuint *ptr4 = (GLuint *) xmesa->xm_draw_buffer->backimage->data;
       if (pixel==0) {
          MEMSET( ptr4, pixel, 4*n );
       }
@@ -668,7 +645,7 @@ clear_32bit_ximage( GLcontext *ctx, GLboolean all,
    else {
       register int i, j;
       for (j=0;j<height;j++) {
-         register GLuint *ptr4 = PIXELADDR4( xmesa->xm_buffer, x, y+j );
+         register GLuint *ptr4 = PIXELADDR4( xmesa->xm_draw_buffer, x, y+j );
          for (i=0;i<width;i++) {
             *ptr4++ = pixel;
          }
@@ -682,11 +659,11 @@ clear_nbit_ximage( GLcontext *ctx, GLboolean all,
                    GLint x, GLint y, GLint width, GLint height )
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
-   XMesaImage *img = xmesa->xm_buffer->backimage;
+   XMesaImage *img = xmesa->xm_draw_buffer->backimage;
    if (all) {
       register int i, j;
-      width = xmesa->xm_buffer->width;
-      height = xmesa->xm_buffer->height;
+      width = xmesa->xm_draw_buffer->width;
+      height = xmesa->xm_draw_buffer->height;
       for (j=0;j<height;j++) {
          for (i=0;i<width;i++) {
             XMesaPutPixel( img, i, j, xmesa->clearpixel );
@@ -696,7 +673,7 @@ clear_nbit_ximage( GLcontext *ctx, GLboolean all,
    else {
       /* TODO: optimize this */
       register int i, j;
-      y = FLIP(xmesa->xm_buffer, y);
+      y = FLIP(xmesa->xm_draw_buffer, y);
       for (j=0;j<height;j++) {
          for (i=0;i<width;i++) {
             XMesaPutPixel( img, x+i, y-j, xmesa->clearpixel );
@@ -715,7 +692,7 @@ clear_buffers( GLcontext *ctx, GLbitfield mask,
    const GLuint *colorMask = (GLuint *) &ctx->Color.ColorMask;
 
    if ((mask & (DD_FRONT_LEFT_BIT | DD_BACK_LEFT_BIT)) &&
-       xmesa->xm_buffer->mesa_buffer.UseSoftwareAlphaBuffers &&
+       xmesa->xm_draw_buffer->mesa_buffer.UseSoftwareAlphaBuffers &&
        ctx->Color.ColorMask[ACOMP]) {
       _mesa_clear_alpha_buffers(ctx);
    }
@@ -723,13 +700,13 @@ clear_buffers( GLcontext *ctx, GLbitfield mask,
    /* we can't handle color or index masking */
    if (*colorMask == 0xffffffff && ctx->Color.IndexMask == 0xffffffff) {
       if (mask & DD_FRONT_LEFT_BIT) {
-	 ASSERT(xmesa->xm_buffer->front_clear_func);
-	 (*xmesa->xm_buffer->front_clear_func)( ctx, all, x, y, width, height );
+	 ASSERT(xmesa->xm_draw_buffer->front_clear_func);
+	 (*xmesa->xm_draw_buffer->front_clear_func)( ctx, all, x, y, width, height );
 	 mask &= ~DD_FRONT_LEFT_BIT;
       }
       if (mask & DD_BACK_LEFT_BIT) {
-	 ASSERT(xmesa->xm_buffer->back_clear_func);
-	 (*xmesa->xm_buffer->back_clear_func)( ctx, all, x, y, width, height );
+	 ASSERT(xmesa->xm_draw_buffer->back_clear_func);
+	 (*xmesa->xm_draw_buffer->back_clear_func)( ctx, all, x, y, width, height );
 	 mask &= ~DD_BACK_LEFT_BIT;
       }
    }
@@ -802,8 +779,8 @@ drawpixels_8R8G8B( GLcontext *ctx,
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
    XMesaDisplay *dpy = xmesa->xm_visual->display;
-   XMesaDrawable buffer = xmesa->xm_buffer->buffer;
-   XMesaGC gc = xmesa->xm_buffer->gc;
+   XMesaDrawable buffer = xmesa->xm_draw_buffer->buffer;
+   XMesaGC gc = xmesa->xm_draw_buffer->gc;
    assert(dpy);
    assert(buffer);
    assert(gc);
@@ -833,7 +810,7 @@ drawpixels_8R8G8B( GLcontext *ctx,
          ximage.red_mask   = 0xff0000;
          ximage.green_mask = 0x00ff00;
          ximage.blue_mask  = 0x0000ff;
-         dstY = FLIP(xmesa->xm_buffer,dstY) - height + 1;
+         dstY = FLIP(xmesa->xm_draw_buffer,dstY) - height + 1;
          XPutImage(dpy, buffer, gc, &ximage, srcX, srcY, dstX, dstY, w, h);
          return GL_TRUE;
       }
@@ -899,33 +876,33 @@ void xmesa_update_state( GLcontext *ctx, GLuint new_state )
 
 
    /* setup pointers to front and back buffer clear functions */
-   xmesa->xm_buffer->front_clear_func = clear_front_pixmap;
-   if (xmesa->xm_buffer->backpixmap != XIMAGE) {
-      xmesa->xm_buffer->back_clear_func = clear_back_pixmap;
+   xmesa->xm_draw_buffer->front_clear_func = clear_front_pixmap;
+   if (xmesa->xm_draw_buffer->backpixmap != XIMAGE) {
+      xmesa->xm_draw_buffer->back_clear_func = clear_back_pixmap;
    }
    else if (sizeof(GLushort)!=2 || sizeof(GLuint)!=4) {
-      xmesa->xm_buffer->back_clear_func = clear_nbit_ximage;
+      xmesa->xm_draw_buffer->back_clear_func = clear_nbit_ximage;
    }
    else switch (xmesa->xm_visual->BitsPerPixel) {
    case 8:
       if (xmesa->xm_visual->hpcr_clear_flag) {
-	 xmesa->xm_buffer->back_clear_func = clear_HPCR_ximage;
+	 xmesa->xm_draw_buffer->back_clear_func = clear_HPCR_ximage;
       }
       else {
-	 xmesa->xm_buffer->back_clear_func = clear_8bit_ximage;
+	 xmesa->xm_draw_buffer->back_clear_func = clear_8bit_ximage;
       }
       break;
    case 16:
-      xmesa->xm_buffer->back_clear_func = clear_16bit_ximage;
+      xmesa->xm_draw_buffer->back_clear_func = clear_16bit_ximage;
       break;
    case 24:
-      xmesa->xm_buffer->back_clear_func = clear_24bit_ximage;
+      xmesa->xm_draw_buffer->back_clear_func = clear_24bit_ximage;
       break;
    case 32:
-      xmesa->xm_buffer->back_clear_func = clear_32bit_ximage;
+      xmesa->xm_draw_buffer->back_clear_func = clear_32bit_ximage;
       break;
    default:
-      xmesa->xm_buffer->back_clear_func = clear_nbit_ximage;
+      xmesa->xm_draw_buffer->back_clear_func = clear_nbit_ximage;
       break;
    }
 
@@ -940,6 +917,7 @@ void xmesa_update_state( GLcontext *ctx, GLuint new_state )
 void xmesa_init_pointers( GLcontext *ctx )
 {
    TNLcontext *tnl;
+   struct swrast_device_driver *dd = _swrast_GetDeviceDriverReference( ctx );
 
    ctx->Driver.GetString = get_string;
    ctx->Driver.GetBufferSize = get_buffer_size;
@@ -955,6 +933,7 @@ void xmesa_init_pointers( GLcontext *ctx )
    ctx->Driver.CopyPixels = _swrast_CopyPixels;
    ctx->Driver.DrawPixels = _swrast_DrawPixels;
    ctx->Driver.ReadPixels = _swrast_ReadPixels;
+   ctx->Driver.DrawBuffer = _swrast_DrawBuffer;
 
    /* Software texture functions:
     */
@@ -987,7 +966,6 @@ void xmesa_init_pointers( GLcontext *ctx )
 
    /* Statechange callbacks:
     */
-   ctx->Driver.SetDrawBuffer = set_draw_buffer;
    ctx->Driver.ClearIndex = clear_index;
    ctx->Driver.ClearColor = clear_color;
    ctx->Driver.IndexMask = index_mask;
@@ -1000,6 +978,8 @@ void xmesa_init_pointers( GLcontext *ctx )
    tnl = TNL_CONTEXT(ctx);
    tnl->Driver.RunPipeline = _tnl_run_pipeline;
    
+   dd->SetBuffer = set_buffer;
+
    /* Install swsetup for tnl->Driver.Render.*:
     */
    _swsetup_Wakeup(ctx);
diff --git a/src/mesa/drivers/x11/xm_span.c b/src/mesa/drivers/x11/xm_span.c
index cbb138a0b3c..eed8c91a968 100644
--- a/src/mesa/drivers/x11/xm_span.c
+++ b/src/mesa/drivers/x11/xm_span.c
@@ -1,4 +1,4 @@
-/* $Id: xm_span.c,v 1.14 2002/03/01 04:28:32 brianp Exp $ */
+/* $Id: xm_span.c,v 1.15 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -3472,14 +3472,9 @@ static void read_index_span( const GLcontext *ctx,
 			     GLuint n, GLint x, GLint y, GLuint index[] )
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
-   XMesaBuffer source;
+   XMesaBuffer source = xmesa->xm_buffer;
    GLuint i;
 
-   if (xmesa->use_read_buffer)
-      source = xmesa->xm_read_buffer;
-   else
-      source = xmesa->xm_buffer;
-
    y = FLIP(source, y);
 
    if (source->buffer) {
@@ -3528,12 +3523,7 @@ static void read_color_span( const GLcontext *ctx,
                              GLubyte rgba[][4] )
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
-   XMesaBuffer source;
-
-   if (xmesa->use_read_buffer)
-      source = xmesa->xm_read_buffer;
-   else
-      source = xmesa->xm_buffer;
+   XMesaBuffer source = xmesa->xm_buffer;
 
    if (source->buffer) {
       /* Read from Pixmap or Window */
@@ -3902,12 +3892,7 @@ static void read_index_pixels( const GLcontext *ctx,
 {
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
    register GLuint i;
-   XMesaBuffer source;
-
-   if (xmesa->use_read_buffer)
-      source = xmesa->xm_read_buffer;
-   else
-      source = xmesa->xm_buffer;
+   XMesaBuffer source = xmesa->xm_buffer;
 
    if (source->buffer) {
       for (i=0;i<n;i++) {
@@ -3937,15 +3922,8 @@ static void read_color_pixels( const GLcontext *ctx,
    const XMesaContext xmesa = (XMesaContext) ctx->DriverCtx;
    XMesaDisplay *dpy = xmesa->xm_visual->display;
    register GLuint i;
-   XMesaBuffer source;
-   XMesaDrawable buffer;
-
-   if (xmesa->use_read_buffer)
-      source = xmesa->xm_read_buffer;
-   else
-      source = xmesa->xm_buffer;
-
-   buffer = source->buffer;  /* the X drawable */
+   XMesaBuffer source = xmesa->xm_buffer;
+   XMesaDrawable buffer = source->buffer;  /* the X drawable */
 
    if (source->buffer) {
       switch (xmesa->pixelformat) {
@@ -4491,6 +4469,4 @@ void xmesa_update_span_funcs( GLcontext *ctx )
    dd->ReadRGBASpan = read_color_span;
    dd->ReadCI32Pixels = read_index_pixels;
    dd->ReadRGBAPixels = read_color_pixels;
-
-   dd->SetReadBuffer = xmesa_set_read_buffer;
 }
diff --git a/src/mesa/drivers/x11/xmesaP.h b/src/mesa/drivers/x11/xmesaP.h
index ae90d995733..5e3ef9e8d97 100644
--- a/src/mesa/drivers/x11/xmesaP.h
+++ b/src/mesa/drivers/x11/xmesaP.h
@@ -1,4 +1,4 @@
-/* $Id: xmesaP.h,v 1.28 2002/05/27 17:06:59 brianp Exp $ */
+/* $Id: xmesaP.h,v 1.29 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -120,9 +120,9 @@ struct xmesa_visual {
 struct xmesa_context {
    GLcontext *gl_ctx;		/* the core library context */
    XMesaVisual xm_visual;	/* Describes the buffers */
-   XMesaBuffer xm_buffer;	/* current draw framebuffer */
+   XMesaBuffer xm_draw_buffer;	/* current draw framebuffer */
    XMesaBuffer xm_read_buffer;	/* current read framebuffer */
-   GLboolean use_read_buffer;	/* read from the xm_read_buffer/ */
+   XMesaBuffer xm_buffer;	/* current span/point/line/triangle buffer */
 
    XMesaDisplay *display;	/* == xm_visual->display */
    GLboolean swapbytes;		/* Host byte order != display byte order? */
@@ -149,6 +149,7 @@ typedef enum {
  */
 struct xmesa_buffer {
    GLframebuffer mesa_buffer;	/* depth, stencil, accum, etc buffers */
+				/* This MUST BE FIRST! */
    GLboolean wasCurrent;	/* was ever the current buffer? */
    XMesaVisual xm_visual;	/* the X/Mesa visual */
 
@@ -536,9 +537,6 @@ extern GLboolean XMesaForceCurrent(XMesaContext c);
 extern GLboolean XMesaLoseCurrent(XMesaContext c);
 extern void XMesaReset( void );
 
-extern void xmesa_set_read_buffer( GLcontext *ctx, 
-				   GLframebuffer *buffer, GLenum mode );
-
 extern void xmesa_resize_buffers( GLframebuffer *buffer );
 
 #endif
diff --git a/src/mesa/main/buffers.c b/src/mesa/main/buffers.c
index c549e2736c4..04a490ada5d 100644
--- a/src/mesa/main/buffers.c
+++ b/src/mesa/main/buffers.c
@@ -1,4 +1,4 @@
-/* $Id: buffers.c,v 1.36 2002/06/15 02:38:15 brianp Exp $ */
+/* $Id: buffers.c,v 1.37 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -121,14 +121,14 @@ _mesa_Clear( GLbitfield mask )
 
       /* don't clear depth buffer if depth writing disabled */
       if (!ctx->Depth.Mask)
-         CLEAR_BITS(mask, GL_DEPTH_BUFFER_BIT);
+         mask &= ~GL_DEPTH_BUFFER_BIT;
 
       /* Build bitmask to send to driver Clear function */
       ddMask = mask & (GL_DEPTH_BUFFER_BIT |
                        GL_STENCIL_BUFFER_BIT |
                        GL_ACCUM_BUFFER_BIT);
       if (mask & GL_COLOR_BUFFER_BIT) {
-         ddMask |= ctx->Color.DrawDestMask;
+         ddMask |= ctx->Color._DrawDestMask;
       }
 
       ASSERT(ctx->Driver.Clear);
@@ -148,6 +148,9 @@ _mesa_DrawBuffer( GLenum mode )
    if (MESA_VERBOSE & VERBOSE_API)
       _mesa_debug(ctx, "glDrawBuffer %s\n", _mesa_lookup_enum_by_nr(mode));
 
+   /*
+    * Do error checking and compute the _DrawDestMask bitfield.
+    */
    switch (mode) {
       case GL_AUX0:
       case GL_AUX1:
@@ -161,16 +164,16 @@ _mesa_DrawBuffer( GLenum mode )
             _mesa_error( ctx, GL_INVALID_OPERATION, "glDrawBuffer" );
             return;}
          if (ctx->Visual.doubleBufferMode)
-            ctx->Color.DrawDestMask = FRONT_RIGHT_BIT | BACK_RIGHT_BIT;
+            ctx->Color._DrawDestMask = FRONT_RIGHT_BIT | BACK_RIGHT_BIT;
          else
-            ctx->Color.DrawDestMask = FRONT_RIGHT_BIT;
+            ctx->Color._DrawDestMask = FRONT_RIGHT_BIT;
          break;
       case GL_FRONT_RIGHT:
          if (!ctx->Visual.stereoMode) {
             _mesa_error( ctx, GL_INVALID_OPERATION, "glDrawBuffer" );
             return;
          }
-         ctx->Color.DrawDestMask = FRONT_RIGHT_BIT;
+         ctx->Color._DrawDestMask = FRONT_RIGHT_BIT;
          break;
       case GL_BACK_RIGHT:
          if (!ctx->Visual.stereoMode) {
@@ -181,14 +184,14 @@ _mesa_DrawBuffer( GLenum mode )
             _mesa_error( ctx, GL_INVALID_OPERATION, "glDrawBuffer" );
             return;
          }
-         ctx->Color.DrawDestMask = BACK_RIGHT_BIT;
+         ctx->Color._DrawDestMask = BACK_RIGHT_BIT;
          break;
       case GL_BACK_LEFT:
          if (!ctx->Visual.doubleBufferMode) {
             _mesa_error( ctx, GL_INVALID_OPERATION, "glDrawBuffer" );
             return;
          }
-         ctx->Color.DrawDestMask = BACK_LEFT_BIT;
+         ctx->Color._DrawDestMask = BACK_LEFT_BIT;
          break;
       case GL_FRONT_AND_BACK:
          if (!ctx->Visual.doubleBufferMode) {
@@ -196,10 +199,10 @@ _mesa_DrawBuffer( GLenum mode )
             return;
          }
          if (ctx->Visual.stereoMode)
-            ctx->Color.DrawDestMask = FRONT_LEFT_BIT | BACK_LEFT_BIT
+            ctx->Color._DrawDestMask = FRONT_LEFT_BIT | BACK_LEFT_BIT
                                     | FRONT_RIGHT_BIT | BACK_RIGHT_BIT;
          else
-            ctx->Color.DrawDestMask = FRONT_LEFT_BIT | BACK_LEFT_BIT;
+            ctx->Color._DrawDestMask = FRONT_LEFT_BIT | BACK_LEFT_BIT;
          break;
       case GL_BACK:
          if (!ctx->Visual.doubleBufferMode) {
@@ -207,74 +210,45 @@ _mesa_DrawBuffer( GLenum mode )
             return;
          }
          if (ctx->Visual.stereoMode)
-            ctx->Color.DrawDestMask = BACK_LEFT_BIT | BACK_RIGHT_BIT;
+            ctx->Color._DrawDestMask = BACK_LEFT_BIT | BACK_RIGHT_BIT;
          else
-            ctx->Color.DrawDestMask = BACK_LEFT_BIT;
+            ctx->Color._DrawDestMask = BACK_LEFT_BIT;
          break;
       case GL_LEFT:
          /* never an error */
          if (ctx->Visual.doubleBufferMode)
-            ctx->Color.DrawDestMask = FRONT_LEFT_BIT | BACK_LEFT_BIT;
+            ctx->Color._DrawDestMask = FRONT_LEFT_BIT | BACK_LEFT_BIT;
          else
-            ctx->Color.DrawDestMask = FRONT_LEFT_BIT;
+            ctx->Color._DrawDestMask = FRONT_LEFT_BIT;
          break;
       case GL_FRONT_LEFT:
          /* never an error */
-         ctx->Color.DrawDestMask = FRONT_LEFT_BIT;
+         ctx->Color._DrawDestMask = FRONT_LEFT_BIT;
          break;
       case GL_FRONT:
          /* never an error */
          if (ctx->Visual.stereoMode)
-            ctx->Color.DrawDestMask = FRONT_LEFT_BIT | FRONT_RIGHT_BIT;
+            ctx->Color._DrawDestMask = FRONT_LEFT_BIT | FRONT_RIGHT_BIT;
          else
-            ctx->Color.DrawDestMask = FRONT_LEFT_BIT;
+            ctx->Color._DrawDestMask = FRONT_LEFT_BIT;
          break;
       case GL_NONE:
          /* never an error */
-         ctx->Color.DrawDestMask = 0;
+         ctx->Color._DrawDestMask = 0;
          break;
       default:
          _mesa_error( ctx, GL_INVALID_ENUM, "glDrawBuffer" );
          return;
    }
 
-   /*
-    * Make the dest buffer mode more precise if possible
-    */
-   if (mode == GL_LEFT && !ctx->Visual.doubleBufferMode)
-      ctx->Color.DriverDrawBuffer = GL_FRONT_LEFT;
-   else if (mode == GL_RIGHT && !ctx->Visual.doubleBufferMode)
-      ctx->Color.DriverDrawBuffer = GL_FRONT_RIGHT;
-   else if (mode == GL_FRONT && !ctx->Visual.stereoMode)
-      ctx->Color.DriverDrawBuffer = GL_FRONT_LEFT;
-   else if (mode == GL_BACK && !ctx->Visual.stereoMode)
-      ctx->Color.DriverDrawBuffer = GL_BACK_LEFT;
-   else
-      ctx->Color.DriverDrawBuffer = mode;
-
-   /*
-    * Set current alpha buffer pointer
-    */
-   if (ctx->DrawBuffer->UseSoftwareAlphaBuffers) {
-      if (ctx->Color.DriverDrawBuffer == GL_FRONT_LEFT)
-         ctx->DrawBuffer->Alpha = ctx->DrawBuffer->FrontLeftAlpha;
-      else if (ctx->Color.DriverDrawBuffer == GL_BACK_LEFT)
-         ctx->DrawBuffer->Alpha = ctx->DrawBuffer->BackLeftAlpha;
-      else if (ctx->Color.DriverDrawBuffer == GL_FRONT_RIGHT)
-         ctx->DrawBuffer->Alpha = ctx->DrawBuffer->FrontRightAlpha;
-      else if (ctx->Color.DriverDrawBuffer == GL_BACK_RIGHT)
-         ctx->DrawBuffer->Alpha = ctx->DrawBuffer->BackRightAlpha;
-   }
+   ctx->Color.DrawBuffer = mode;
+   ctx->NewState |= _NEW_COLOR;
 
    /*
-    * If we get here there can't have been an error.  Now tell the
-    * device driver about it.  
+    * Call device driver function.
     */
-   ASSERT(ctx->Driver.SetDrawBuffer);
-   (*ctx->Driver.SetDrawBuffer)(ctx, ctx->Color.DriverDrawBuffer);
-
-   ctx->Color.DrawBuffer = mode;
-   ctx->NewState |= _NEW_COLOR;
+   if (ctx->Driver.DrawBuffer)
+      (*ctx->Driver.DrawBuffer)(ctx, mode);
 }
 
 
@@ -300,7 +274,7 @@ _mesa_ReadBuffer( GLenum mode )
       case GL_FRONT:
       case GL_FRONT_LEFT:
          /* Front-Left buffer, always exists */
-         ctx->Pixel.DriverReadBuffer = GL_FRONT_LEFT;
+         ctx->Pixel._DriverReadBuffer = GL_FRONT_LEFT;
          break;
       case GL_BACK:
       case GL_BACK_LEFT:
@@ -309,7 +283,7 @@ _mesa_ReadBuffer( GLenum mode )
             _mesa_error( ctx, GL_INVALID_OPERATION, "glReadBuffer" );
             return;
          }
-         ctx->Pixel.DriverReadBuffer = GL_BACK_LEFT;
+         ctx->Pixel._DriverReadBuffer = GL_BACK_LEFT;
          break;
       case GL_FRONT_RIGHT:
       case GL_RIGHT:
@@ -317,14 +291,14 @@ _mesa_ReadBuffer( GLenum mode )
             _mesa_error( ctx, GL_INVALID_OPERATION, "glReadBuffer" );
             return;
          }
-         ctx->Pixel.DriverReadBuffer = GL_FRONT_RIGHT;
+         ctx->Pixel._DriverReadBuffer = GL_FRONT_RIGHT;
          break;
       case GL_BACK_RIGHT:
          if (!ctx->Visual.stereoMode || !ctx->Visual.doubleBufferMode) {
             _mesa_error( ctx, GL_INVALID_OPERATION, "glReadBuffer" );
             return;
          }
-         ctx->Pixel.DriverReadBuffer = GL_BACK_RIGHT;
+         ctx->Pixel._DriverReadBuffer = GL_BACK_RIGHT;
          break;
       default:
          _mesa_error( ctx, GL_INVALID_ENUM, "glReadBuffer" );
@@ -333,6 +307,12 @@ _mesa_ReadBuffer( GLenum mode )
 
    ctx->Pixel.ReadBuffer = mode;
    ctx->NewState |= _NEW_PIXEL;
+
+   /*
+    * Call device driver function.
+    */
+   if (ctx->Driver.ReadBuffer)
+      (*ctx->Driver.ReadBuffer)(ctx, mode);
 }
 
 
diff --git a/src/mesa/main/colortab.c b/src/mesa/main/colortab.c
index 417954369ae..88963dccc68 100644
--- a/src/mesa/main/colortab.c
+++ b/src/mesa/main/colortab.c
@@ -1,4 +1,4 @@
-/* $Id: colortab.c,v 1.44 2002/06/29 19:48:15 brianp Exp $ */
+/* $Id: colortab.c,v 1.45 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -36,7 +36,6 @@
 #include "mem.h"
 #include "mmath.h"
 #include "state.h"
-#include "swrast/s_span.h" /* XXX SWRAST hack */
 #endif
 
 
diff --git a/src/mesa/main/context.c b/src/mesa/main/context.c
index 9a141d9db20..7fa32c601c0 100644
--- a/src/mesa/main/context.c
+++ b/src/mesa/main/context.c
@@ -1,4 +1,4 @@
-/* $Id: context.c,v 1.174 2002/06/29 19:48:15 brianp Exp $ */
+/* $Id: context.c,v 1.175 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -978,7 +978,6 @@ init_attrib_groups( GLcontext *ctx )
    ctx->Color.ColorLogicOpEnabled = GL_FALSE;
    ctx->Color.LogicOp = GL_COPY;
    ctx->Color.DitherFlag = GL_TRUE;
-   ctx->Color.MultiDrawBuffer = GL_FALSE;
 
    /* Current group */
    ASSIGN_4V( ctx->Current.Attrib[VERT_ATTRIB_WEIGHT], 0.0, 0.0, 0.0, 0.0 );
@@ -1689,17 +1688,17 @@ _mesa_initialize_context( GLcontext *ctx,
 
    if (visual->doubleBufferMode) {
       ctx->Color.DrawBuffer = GL_BACK;
-      ctx->Color.DriverDrawBuffer = GL_BACK_LEFT;
-      ctx->Color.DrawDestMask = BACK_LEFT_BIT;
+      ctx->Color._DriverDrawBuffer = GL_BACK_LEFT;
+      ctx->Color._DrawDestMask = BACK_LEFT_BIT;
       ctx->Pixel.ReadBuffer = GL_BACK;
-      ctx->Pixel.DriverReadBuffer = GL_BACK_LEFT;
+      ctx->Pixel._DriverReadBuffer = GL_BACK_LEFT;
    }
    else {
       ctx->Color.DrawBuffer = GL_FRONT;
-      ctx->Color.DriverDrawBuffer = GL_FRONT_LEFT;
-      ctx->Color.DrawDestMask = FRONT_LEFT_BIT;
+      ctx->Color._DriverDrawBuffer = GL_FRONT_LEFT;
+      ctx->Color._DrawDestMask = FRONT_LEFT_BIT;
       ctx->Pixel.ReadBuffer = GL_FRONT;
-      ctx->Pixel.DriverReadBuffer = GL_FRONT_LEFT;
+      ctx->Pixel._DriverReadBuffer = GL_FRONT_LEFT;
    }
 
    if (!alloc_proxy_textures(ctx)) {
@@ -1716,6 +1715,8 @@ _mesa_initialize_context( GLcontext *ctx,
    _glapi_add_entrypoint("glCompressedTexSubImage2DARB", 558);
    _glapi_add_entrypoint("glCompressedTexSubImage1DARB", 559);
    _glapi_add_entrypoint("glGetCompressedTexImageARB", 560);
+   /* XXX we should add a bunch of new functions here */
+
 
    /* Find the larger of Mesa's dispatch table and libGL's dispatch table.
     * In practice, this'll be the same for stand-alone Mesa.  But for DRI
diff --git a/src/mesa/main/convolve.c b/src/mesa/main/convolve.c
index cf88bbcb7d2..ce01a121871 100644
--- a/src/mesa/main/convolve.c
+++ b/src/mesa/main/convolve.c
@@ -1,4 +1,4 @@
-/* $Id: convolve.c,v 1.26 2002/03/19 15:22:50 brianp Exp $ */
+/* $Id: convolve.c,v 1.27 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -43,7 +43,6 @@
 #include "image.h"
 #include "mtypes.h"
 #include "state.h"
-#include "swrast/s_span.h" /* XXX SWRAST hack */
 #endif
 
 
diff --git a/src/mesa/main/dd.h b/src/mesa/main/dd.h
index 1a100102ae4..81ae9e4a125 100644
--- a/src/mesa/main/dd.h
+++ b/src/mesa/main/dd.h
@@ -1,4 +1,4 @@
-/* $Id: dd.h,v 1.69 2002/06/15 02:38:15 brianp Exp $ */
+/* $Id: dd.h,v 1.70 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -48,11 +48,6 @@ struct gl_pixelstore_attrib;
  */
 struct dd_function_table {
 
-   /**********************************************************************
-    *** Mandatory functions:  these functions must be implemented by   ***
-    *** every device driver.                                           ***
-    **********************************************************************/
-
    const GLubyte * (*GetString)( GLcontext *ctx, GLenum name );
    /* Return a string as needed by glGetString().
     * Only the GL_RENDERER token must be implemented.  Otherwise,
@@ -74,28 +69,23 @@ struct dd_function_table {
     * If 'all' is true then the clear the whole buffer, else clear only the
     * region defined by (x,y,width,height).
     * This function must obey the glColorMask, glIndexMask and glStencilMask
-    * settings!  Software Mesa can do masked clears if the device driver can't.
+    * settings!
+    * Software Mesa can do masked clears if the device driver can't.
     */
 
-   void (*SetDrawBuffer)( GLcontext *ctx, GLenum buffer );
+   void (*DrawBuffer)( GLcontext *ctx, GLenum buffer );
    /*
-    * Specifies the current buffer for writing.
-    * The following values must be accepted when applicable:
-    *    GL_FRONT_LEFT - this buffer always exists
-    *    GL_BACK_LEFT - when double buffering
-    *    GL_FRONT_RIGHT - when using stereo
-    *    GL_BACK_RIGHT - when using stereo and double buffering
-    *    GL_FRONT - write to front left and front right if it exists
-    *    GL_BACK - write to back left and back right if it exists
-    *    GL_LEFT - write to front left and back left if it exists
-    *    GL_RIGHT - write to right left and back right if they exist
-    *    GL_FRONT_AND_BACK - write to all four buffers if they exist
-    *    GL_NONE - disable buffer write in device driver.
-    *
+    * Specifies the current buffer for writing.  Called via glDrawBuffer().
     * Note the driver must organize fallbacks (eg with swrast) if it
     * cannot implement the requested mode.
     */
 
+
+   void (*ReadBuffer)( GLcontext *ctx, GLenum buffer );
+   /*
+    * Specifies the current buffer for reading.  Called via glReadBuffer().
+    */
+
    void (*GetBufferSize)( GLframebuffer *buffer,
                           GLuint *width, GLuint *height );
    /*
@@ -520,7 +510,6 @@ struct dd_function_table {
    void (*TextureMatrix)(GLcontext *ctx, GLuint unit, const GLmatrix *mat);
    void (*Viewport)(GLcontext *ctx, GLint x, GLint y, GLsizei w, GLsizei h);
 
-
    /***
     *** Vertex array functions
     ***
@@ -555,8 +544,6 @@ struct dd_function_table {
    GLboolean (*GetIntegerv)(GLcontext *ctx, GLenum pname, GLint *result);
    GLboolean (*GetPointerv)(GLcontext *ctx, GLenum pname, GLvoid **result);
 
-
-
    /***
     *** Support for multiple t&l engines
     ***/
diff --git a/src/mesa/main/get.c b/src/mesa/main/get.c
index a4673bf1c0e..4f12e06b414 100644
--- a/src/mesa/main/get.c
+++ b/src/mesa/main/get.c
@@ -1,4 +1,4 @@
-/* $Id: get.c,v 1.86 2002/06/29 20:04:57 brianp Exp $ */
+/* $Id: get.c,v 1.87 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -5596,7 +5596,7 @@ _mesa_GetString( GLenum name )
    static const char *renderer = "Mesa";
    static const char *version_1_2 = "1.2 Mesa 4.1 beta";
    static const char *version_1_3 = "1.3 Mesa 4.1 beta";
-   static const char *version_1_4 = "1.4 Mesa 4.1 beta";
+   static const char *version_1_4 = "1.3 Mesa 4.1 beta"; /* change to 1.4 */
 
    ASSERT_OUTSIDE_BEGIN_END_WITH_RETVAL(ctx, 0);
 
diff --git a/src/mesa/main/macros.h b/src/mesa/main/macros.h
index 038518d90aa..37f4f16f268 100644
--- a/src/mesa/main/macros.h
+++ b/src/mesa/main/macros.h
@@ -1,4 +1,4 @@
-/* $Id: macros.h,v 1.28 2002/06/12 00:52:50 brianp Exp $ */
+/* $Id: macros.h,v 1.29 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -59,15 +59,6 @@
 #endif
 
 
-
-/*
- * Bitmask helpers
- */
-#define SET_BITS(WORD, BITS)    (WORD) |= (BITS)
-#define CLEAR_BITS(WORD, BITS)  (WORD) &= ~(BITS)
-#define TEST_BITS(WORD, BITS)   ((WORD) & (BITS))
-
-
 /* Stepping a GLfloat pointer by a byte stride
  */
 #define STRIDE_F(p, i)  (p = (GLfloat *)((GLubyte *)p + i))
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index b5798bc0942..6f33ae6658d 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -1,4 +1,4 @@
-/* $Id: mtypes.h,v 1.83 2002/06/29 20:03:14 brianp Exp $ */
+/* $Id: mtypes.h,v 1.84 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -317,9 +317,8 @@ struct gl_colorbuffer_attrib {
    GLubyte ColorMask[4];		/* Each flag is 0xff or 0x0 */
 
    GLenum DrawBuffer;			/* Which buffer to draw into */
-   GLenum DriverDrawBuffer;		/* Current device driver dest buffer */
-   GLboolean MultiDrawBuffer;		/* Drawing to multiple buffers? */
-   GLubyte DrawDestMask;		/* bitwise-OR of bitflags above */
+   GLenum _DriverDrawBuffer;		/* Single src/dst buffer for drivers */
+   GLubyte _DrawDestMask;		/* bitwise-OR of bitflags above */
 
    /* alpha testing */
    GLboolean AlphaEnabled;		/* Alpha test enabled flag */
@@ -599,7 +598,7 @@ struct gl_multisample_attrib {
 
 struct gl_pixel_attrib {
    GLenum ReadBuffer;		/* src buffer for glRead/CopyPixels */
-   GLenum DriverReadBuffer;	/* Driver's current source buffer */
+   GLenum _DriverReadBuffer;	/* Driver's current source buffer */
    GLfloat RedBias, RedScale;
    GLfloat GreenBias, GreenScale;
    GLfloat BlueBias, BlueScale;
@@ -1315,7 +1314,6 @@ struct gl_frame_buffer {
    GLchan *BackLeftAlpha;	/* array [Width*Height] of GLubyte */
    GLchan *FrontRightAlpha;	/* array [Width*Height] of GLubyte */
    GLchan *BackRightAlpha;	/* array [Width*Height] of GLubyte */
-   GLchan *Alpha;		/* Points to current alpha buffer */
 
    /* Drawing bounds: intersection of window size and scissor box */
    GLint _Xmin, _Ymin;  /* inclusive */
@@ -1431,7 +1429,9 @@ struct gl_extensions {
 };
 
 
-/* XXX just an idea */
+/*
+ * A stack of matrices (projection, modelview, color, texture, etc).
+ */
 struct matrix_stack
 {
    GLmatrix *Top;      /* points into Stack */
@@ -1532,7 +1532,9 @@ struct matrix_stack
 #define _NEW_ARRAY_TEXCOORD(i) (_NEW_ARRAY_TEXCOORD_0 << (i))
 #define _NEW_ARRAY_ATTRIB(i) (_NEW_ARRAY_ATTRIB_0 << (i))
 
+
 /* A bunch of flags that we think might be useful to drivers.
+ * Set in the ctx->_TriangleCaps bitfield.
  */
 #define DD_FLATSHADE                0x1
 #define DD_SEPARATE_SPECULAR        0x2
@@ -1549,6 +1551,7 @@ struct matrix_stack
 #define DD_POINT_SIZE               0x1000
 #define DD_POINT_ATTEN              0x2000
 
+
 /* Define the state changes under which each of these bits might change
  */
 #define _DD_NEW_FLATSHADE                _NEW_LIGHT
diff --git a/src/mesa/main/state.c b/src/mesa/main/state.c
index 27e7e0017ad..500ba2640ff 100644
--- a/src/mesa/main/state.c
+++ b/src/mesa/main/state.c
@@ -1,4 +1,4 @@
-/* $Id: state.c,v 1.88 2002/06/30 15:47:01 brianp Exp $ */
+/* $Id: state.c,v 1.89 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -1017,7 +1017,6 @@ void _mesa_update_state( GLcontext *ctx )
    ASSERT(ctx->Driver.GetString);
    ASSERT(ctx->Driver.UpdateState);
    ASSERT(ctx->Driver.Clear);
-   ASSERT(ctx->Driver.SetDrawBuffer);
    ASSERT(ctx->Driver.GetBufferSize);
    if (ctx->Visual.accumRedBits > 0) {
       ASSERT(ctx->Driver.Accum);
diff --git a/src/mesa/main/texformat.c b/src/mesa/main/texformat.c
index 65ad6d2a871..4795aeffb2f 100644
--- a/src/mesa/main/texformat.c
+++ b/src/mesa/main/texformat.c
@@ -1,4 +1,4 @@
-/* $Id: texformat.c,v 1.13 2002/06/29 19:48:16 brianp Exp $ */
+/* $Id: texformat.c,v 1.14 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -40,7 +40,6 @@
 #include "texformat.h"
 #include "teximage.h"
 #include "texstate.h"
-#include "swrast/s_span.h"
 #endif
 
 
diff --git a/src/mesa/main/teximage.c b/src/mesa/main/teximage.c
index 2ff9d891219..95bed13d9d1 100644
--- a/src/mesa/main/teximage.c
+++ b/src/mesa/main/teximage.c
@@ -1,4 +1,4 @@
-/* $Id: teximage.c,v 1.110 2002/06/29 19:48:16 brianp Exp $ */
+/* $Id: teximage.c,v 1.111 2002/07/09 01:22:50 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -41,7 +41,6 @@
 #include "texstate.h"
 #include "texstore.h"
 #include "mtypes.h"
-#include "swrast/s_span.h" /* XXX SWRAST hack */
 #endif
 
 
diff --git a/src/mesa/swrast/s_accum.c b/src/mesa/swrast/s_accum.c
index 09c4d8647b0..0159304c172 100644
--- a/src/mesa/swrast/s_accum.c
+++ b/src/mesa/swrast/s_accum.c
@@ -1,4 +1,4 @@
-/* $Id: s_accum.c,v 1.17 2002/06/15 02:38:17 brianp Exp $ */
+/* $Id: s_accum.c,v 1.18 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -306,8 +306,7 @@ _swrast_Accum( GLcontext *ctx, GLenum op, GLfloat value,
          if (value == 0.0F)
             return;
 
-         (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-					  ctx->Pixel.DriverReadBuffer );
+         _swrast_use_read_buffer(ctx);
 
          /* May have to leave optimized accum buffer mode */
          if (swrast->_IntegerAccumScaler == 0.0 && value > 0.0 && value <= 1.0)
@@ -359,14 +358,13 @@ _swrast_Accum( GLcontext *ctx, GLenum op, GLfloat value,
             }
          }
          /* restore read buffer = draw buffer (the default) */
-         (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-					  ctx->Color.DriverDrawBuffer );
+         _swrast_use_draw_buffer(ctx);
+
          RENDER_FINISH(swrast,ctx);
 	 break;
 
       case GL_LOAD:
-         (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-					  ctx->Pixel.DriverReadBuffer );
+         _swrast_use_read_buffer(ctx);
 
          /* This is a change to go into optimized accum buffer mode */
          if (value > 0.0 && value <= 1.0) {
@@ -433,8 +431,8 @@ _swrast_Accum( GLcontext *ctx, GLenum op, GLfloat value,
          }
 
          /* restore read buffer = draw buffer (the default) */
-         (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-                                       ctx->Color.DriverDrawBuffer );
+         _swrast_use_draw_buffer(ctx);
+
          RENDER_FINISH(swrast,ctx);
 	 break;
 
diff --git a/src/mesa/swrast/s_alphabuf.c b/src/mesa/swrast/s_alphabuf.c
index 56c4d552da2..b303c0fc76c 100644
--- a/src/mesa/swrast/s_alphabuf.c
+++ b/src/mesa/swrast/s_alphabuf.c
@@ -1,4 +1,4 @@
-/* $Id: s_alphabuf.c,v 1.10 2002/03/19 16:47:05 brianp Exp $ */
+/* $Id: s_alphabuf.c,v 1.11 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -38,20 +38,12 @@
 #include "s_alphabuf.h"
 
 
-#define ALPHA_DRAW_ADDR(X,Y) \
-   (ctx->DrawBuffer->Alpha + (Y) * ctx->DrawBuffer->Width + (X))
-
-#define ALPHA_READ_ADDR(X,Y) \
-   (ctx->ReadBuffer->Alpha + (Y) * ctx->ReadBuffer->Width + (X))
-
-
 /*
  * Allocate a new front and back alpha buffer.
  */
 void
 _mesa_alloc_alpha_buffers( GLframebuffer *buffer )
 {
-   GET_CURRENT_CONTEXT(ctx);
    const GLint bytes = buffer->Width * buffer->Height * sizeof(GLchan);
 
    ASSERT(buffer->UseSoftwareAlphaBuffers);
@@ -101,17 +93,6 @@ _mesa_alloc_alpha_buffers( GLframebuffer *buffer )
          }
       }
    }
-
-   if (ctx) {
-      if (ctx->Color.DriverDrawBuffer == GL_FRONT_LEFT)
-         buffer->Alpha = buffer->FrontLeftAlpha;
-      else if (ctx->Color.DriverDrawBuffer == GL_BACK_LEFT)
-         buffer->Alpha = buffer->BackLeftAlpha;
-      else if (ctx->Color.DriverDrawBuffer == GL_FRONT_RIGHT)
-         buffer->Alpha = buffer->FrontRightAlpha;
-      else if (ctx->Color.DriverDrawBuffer == GL_BACK_RIGHT)
-         buffer->Alpha = buffer->BackRightAlpha;
-   }
 }
 
 
@@ -129,7 +110,7 @@ _mesa_clear_alpha_buffers( GLcontext *ctx )
 
    /* loop over four possible alpha buffers */
    for (bufferBit = 1; bufferBit <= 8; bufferBit = bufferBit << 1) {
-      if (bufferBit & ctx->Color.DrawDestMask) {
+      if (bufferBit & ctx->Color._DrawDestMask) {
          GLchan *buffer;
          if (bufferBit == FRONT_LEFT_BIT) {
             buffer = ctx->DrawBuffer->FrontLeftAlpha;
@@ -187,13 +168,39 @@ _mesa_clear_alpha_buffers( GLcontext *ctx )
 
 
 
+static INLINE
+GLchan *get_alpha_buffer( GLcontext *ctx )
+{
+   switch (ctx->Color._DriverDrawBuffer) {
+   case GL_FRONT_LEFT:
+      return ctx->DrawBuffer->FrontLeftAlpha;
+      break;
+   case GL_BACK_LEFT:
+      return ctx->DrawBuffer->BackLeftAlpha;
+      break;
+   case GL_FRONT_RIGHT:
+      return ctx->DrawBuffer->FrontRightAlpha;
+      break;
+   case GL_BACK_RIGHT:
+      return ctx->DrawBuffer->BackRightAlpha;
+      break;
+   default:
+      _mesa_problem(ctx, "Bad DriverDrawBuffer in _mesa_write_alpha_span()");
+      return ctx->DrawBuffer->FrontLeftAlpha; /* aribitrary */
+   }
+}
+
+
 void
 _mesa_write_alpha_span( GLcontext *ctx, GLuint n, GLint x, GLint y,
                         CONST GLchan rgba[][4], const GLubyte mask[] )
 {
-   GLchan *aptr = ALPHA_DRAW_ADDR( x, y );
+   GLchan *buffer, *aptr;
    GLuint i;
 
+   buffer = get_alpha_buffer(ctx);
+   aptr = buffer + y * ctx->DrawBuffer->Width + x;
+
    if (mask) {
       for (i=0;i<n;i++) {
          if (mask[i]) {
@@ -214,9 +221,12 @@ void
 _mesa_write_mono_alpha_span( GLcontext *ctx, GLuint n, GLint x, GLint y,
                              GLchan alpha, const GLubyte mask[] )
 {
-   GLchan *aptr = ALPHA_DRAW_ADDR( x, y );
+   GLchan *buffer, *aptr;
    GLuint i;
 
+   buffer = get_alpha_buffer(ctx);
+   aptr = buffer + y * ctx->DrawBuffer->Width + x;
+
    if (mask) {
       for (i=0;i<n;i++) {
          if (mask[i]) {
@@ -238,19 +248,22 @@ _mesa_write_alpha_pixels( GLcontext *ctx,
                           GLuint n, const GLint x[], const GLint y[],
                           CONST GLchan rgba[][4], const GLubyte mask[] )
 {
+   GLchan *buffer;
    GLuint i;
 
+   buffer = get_alpha_buffer(ctx);
+
    if (mask) {
       for (i=0;i<n;i++) {
          if (mask[i]) {
-            GLchan *aptr = ALPHA_DRAW_ADDR( x[i], y[i] );
+            GLchan *aptr = buffer + y[i] * ctx->DrawBuffer->Width + x[i];
             *aptr = rgba[i][ACOMP];
          }
       }
    }
    else {
       for (i=0;i<n;i++) {
-         GLchan *aptr = ALPHA_DRAW_ADDR( x[i], y[i] );
+         GLchan *aptr = buffer + y[i] * ctx->DrawBuffer->Width + x[i];
          *aptr = rgba[i][ACOMP];
       }
    }
@@ -262,19 +275,22 @@ _mesa_write_mono_alpha_pixels( GLcontext *ctx,
                                GLuint n, const GLint x[], const GLint y[],
                                GLchan alpha, const GLubyte mask[] )
 {
+   GLchan *buffer;
    GLuint i;
 
+   buffer = get_alpha_buffer(ctx);
+
    if (mask) {
       for (i=0;i<n;i++) {
          if (mask[i]) {
-            GLchan *aptr = ALPHA_DRAW_ADDR( x[i], y[i] );
+            GLchan *aptr = buffer + y[i] * ctx->DrawBuffer->Width + x[i];
             *aptr = alpha;
          }
       }
    }
    else {
       for (i=0;i<n;i++) {
-         GLchan *aptr = ALPHA_DRAW_ADDR( x[i], y[i] );
+         GLchan *aptr = buffer + y[i] * ctx->DrawBuffer->Width + x[i];
          *aptr = alpha;
       }
    }
@@ -286,11 +302,14 @@ void
 _mesa_read_alpha_span( GLcontext *ctx,
                        GLuint n, GLint x, GLint y, GLchan rgba[][4] )
 {
-   GLchan *aptr = ALPHA_READ_ADDR( x, y );
+   const GLchan *buffer, *aptr;
    GLuint i;
-   for (i=0;i<n;i++) {
+
+   buffer = get_alpha_buffer(ctx);
+   aptr = buffer + y * ctx->DrawBuffer->Width + x;
+
+   for (i = 0; i < n; i++)
       rgba[i][ACOMP] = *aptr++;
-   }
 }
 
 
@@ -299,10 +318,14 @@ _mesa_read_alpha_pixels( GLcontext *ctx,
                          GLuint n, const GLint x[], const GLint y[],
                          GLchan rgba[][4], const GLubyte mask[] )
 {
+   const GLchan *buffer;
    GLuint i;
-   for (i=0;i<n;i++) {
+
+   buffer = get_alpha_buffer(ctx);
+
+   for (i = 0; i < n; i++) {
       if (mask[i]) {
-         GLchan *aptr = ALPHA_READ_ADDR( x[i], y[i] );
+         const GLchan *aptr = buffer + y[i] * ctx->DrawBuffer->Width + x[i];
          rgba[i][ACOMP] = *aptr;
       }
    }
diff --git a/src/mesa/swrast/s_buffers.c b/src/mesa/swrast/s_buffers.c
index 6c7b447aba8..dcfa26f5e20 100644
--- a/src/mesa/swrast/s_buffers.c
+++ b/src/mesa/swrast/s_buffers.c
@@ -1,4 +1,4 @@
-/* $Id: s_buffers.c,v 1.11 2002/06/15 02:38:17 brianp Exp $ */
+/* $Id: s_buffers.c,v 1.12 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -167,22 +167,18 @@ clear_color_buffers(GLcontext *ctx)
 
    /* loop over four possible dest color buffers */
    for (bufferBit = 1; bufferBit <= 8; bufferBit = bufferBit << 1) {
-      if (bufferBit & ctx->Color.DrawDestMask) {
+      if (bufferBit & ctx->Color._DrawDestMask) {
          if (bufferBit == FRONT_LEFT_BIT) {
-            (*ctx->Driver.SetDrawBuffer)( ctx, GL_FRONT_LEFT);
-            (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer, GL_FRONT_LEFT);
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_FRONT_LEFT);
          }
          else if (bufferBit == FRONT_RIGHT_BIT) {
-            (*ctx->Driver.SetDrawBuffer)( ctx, GL_FRONT_RIGHT);
-            (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer, GL_FRONT_RIGHT);
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_FRONT_RIGHT);
          }
          else if (bufferBit == BACK_LEFT_BIT) {
-            (*ctx->Driver.SetDrawBuffer)( ctx, GL_BACK_LEFT);
-            (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer, GL_BACK_LEFT);
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_BACK_LEFT);
          }
          else {
-            (*ctx->Driver.SetDrawBuffer)( ctx, GL_BACK_RIGHT);
-            (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer, GL_BACK_RIGHT);
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_BACK_RIGHT);
          }
 
          if (colorMask != 0xffffffff) {
@@ -194,9 +190,8 @@ clear_color_buffers(GLcontext *ctx)
       }
    }
 
-   /* restore default read/draw buffers */
-   (void) (*ctx->Driver.SetDrawBuffer)( ctx, ctx->Color.DriverDrawBuffer );
-   (void) (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer, ctx->Pixel.DriverReadBuffer );
+   /* restore default read/draw buffer */
+   _swrast_use_draw_buffer(ctx);
 }
 
 
@@ -224,7 +219,7 @@ _swrast_Clear( GLcontext *ctx, GLbitfield mask,
 
    /* do software clearing here */
    if (mask) {
-      if (mask & ctx->Color.DrawDestMask)   clear_color_buffers(ctx);
+      if (mask & ctx->Color._DrawDestMask)   clear_color_buffers(ctx);
       if (mask & GL_DEPTH_BUFFER_BIT)    _mesa_clear_depth_buffer(ctx);
       if (mask & GL_ACCUM_BUFFER_BIT)    _mesa_clear_accum_buffer(ctx);
       if (mask & GL_STENCIL_BUFFER_BIT)  _mesa_clear_stencil_buffer(ctx);
@@ -258,3 +253,68 @@ _swrast_alloc_buffers( GLframebuffer *buffer )
       _mesa_alloc_alpha_buffers( buffer );
    }
 }
+
+
+/*
+ * Fallback for ctx->Driver.DrawBuffer()
+ */
+void
+_swrast_DrawBuffer( GLcontext *ctx, GLenum mode )
+{
+   _swrast_use_draw_buffer(ctx);
+}
+
+
+/*
+ * Setup things so that we read/write spans from the user-designated
+ * read buffer (set via glReadPixels).  We usually just have to call
+ * this for glReadPixels, glCopyPixels, etc.
+ */
+void
+_swrast_use_read_buffer( GLcontext *ctx )
+{
+   SWcontext *swrast = SWRAST_CONTEXT(ctx);
+
+   /* Do this so the software-emulated alpha plane span functions work! */
+   ctx->Color._DriverDrawBuffer = ctx->Pixel._DriverReadBuffer;
+   /* Tell the device driver where to read/write spans */
+   (*swrast->Driver.SetBuffer)( ctx, ctx->ReadBuffer,
+                                ctx->Pixel._DriverReadBuffer );
+}
+
+
+/*
+ * Setup things so that we read/write spans from the default draw buffer.
+ * This is the usual mode that Mesa's software rasterizer operates in.
+ */
+void
+_swrast_use_draw_buffer( GLcontext *ctx )
+{
+   SWcontext *swrast = SWRAST_CONTEXT(ctx);
+
+   /* The user can specify rendering to zero, one, two, or four color
+    * buffers simultaneously with glDrawBuffer()!
+    * We don't expect the span/point/line/triangle functions to deal with
+    * that mess so we'll iterate over the multiple buffers as needed.
+    * But usually we only render to one color buffer at a time.
+    * We set ctx->Color._DriverDrawBuffer to that buffer and tell the
+    * device driver to use that buffer.
+    * Look in s_span.c's multi_write_rgba_span() function to see how
+    * we loop over multiple color buffers when needed.
+    */
+
+   if (ctx->Color._DrawDestMask & FRONT_LEFT_BIT)
+      ctx->Color._DriverDrawBuffer = GL_FRONT_LEFT;
+   else if (ctx->Color._DrawDestMask & BACK_LEFT_BIT)
+      ctx->Color._DriverDrawBuffer = GL_BACK_LEFT;
+   else if (ctx->Color._DrawDestMask & FRONT_RIGHT_BIT)
+      ctx->Color._DriverDrawBuffer = GL_FRONT_RIGHT;
+   else if (ctx->Color._DrawDestMask & BACK_RIGHT_BIT)
+      ctx->Color._DriverDrawBuffer = GL_BACK_RIGHT;
+   else
+      /* glDrawBuffer(GL_NONE) */
+      ctx->Color._DriverDrawBuffer = GL_FRONT_LEFT; /* always have this */
+
+   (*swrast->Driver.SetBuffer)( ctx, ctx->DrawBuffer,
+                                ctx->Color._DriverDrawBuffer );
+}
diff --git a/src/mesa/swrast/s_context.c b/src/mesa/swrast/s_context.c
index a4f59df8ae3..105b562d90f 100644
--- a/src/mesa/swrast/s_context.c
+++ b/src/mesa/swrast/s_context.c
@@ -1,4 +1,4 @@
-/* $Id: s_context.c,v 1.35 2002/06/15 03:03:11 brianp Exp $ */
+/* $Id: s_context.c,v 1.36 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -87,8 +87,11 @@ _swrast_update_rasterflags( GLcontext *ctx )
     * MULTI_DRAW_BIT flag.  Also set it if we're drawing to no
     * buffers or the RGBA or CI mask disables all writes.
     */
-   if (ctx->Color.DrawBuffer == GL_FRONT_AND_BACK ||
-       ctx->Color.DrawBuffer == GL_NONE) {
+   if (ctx->Color._DrawDestMask != FRONT_LEFT_BIT &&
+       ctx->Color._DrawDestMask != BACK_LEFT_BIT &&
+       ctx->Color._DrawDestMask != FRONT_RIGHT_BIT &&
+       ctx->Color._DrawDestMask != BACK_RIGHT_BIT) {
+      /* more than one color buffer designated for writing (or zero buffers) */
       RasterMask |= MULTI_DRAW_BIT;
    }
    else if (ctx->Visual.rgbMode && *((GLuint *) ctx->Color.ColorMask) == 0) {
diff --git a/src/mesa/swrast/s_copypix.c b/src/mesa/swrast/s_copypix.c
index 2c6bd263123..7f5f41b78f6 100644
--- a/src/mesa/swrast/s_copypix.c
+++ b/src/mesa/swrast/s_copypix.c
@@ -1,4 +1,4 @@
-/* $Id: s_copypix.c,v 1.38 2002/06/15 03:03:11 brianp Exp $ */
+/* $Id: s_copypix.c,v 1.39 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -103,7 +103,6 @@ copy_conv_rgba_pixels(GLcontext *ctx, GLint srcx, GLint srcy,
    GLboolean quick_draw;
    GLint row;
    GLboolean changeBuffer;
-   GLchan *saveReadAlpha;
    const GLboolean zoom = ctx->Pixel.ZoomX != 1.0F || ctx->Pixel.ZoomY != 1.0F;
    const GLuint transferOps = ctx->_ImageTransferState;
    GLfloat *dest, *tmpImage, *convImage;
@@ -128,7 +127,6 @@ copy_conv_rgba_pixels(GLcontext *ctx, GLint srcx, GLint srcy,
    }
 
    /* If read and draw buffer are different we must do buffer switching */
-   saveReadAlpha = ctx->ReadBuffer->Alpha;
    changeBuffer = ctx->Pixel.ReadBuffer != ctx->Color.DrawBuffer
                || ctx->DrawBuffer != ctx->ReadBuffer;
 
@@ -149,16 +147,8 @@ copy_conv_rgba_pixels(GLcontext *ctx, GLint srcx, GLint srcy,
    dest = tmpImage;
 
    if (changeBuffer) {
-      (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                    ctx->Pixel.DriverReadBuffer );
-      if (ctx->Pixel.DriverReadBuffer == GL_FRONT_LEFT)
-         ctx->ReadBuffer->Alpha = ctx->ReadBuffer->FrontLeftAlpha;
-      else if (ctx->Pixel.DriverReadBuffer == GL_BACK_LEFT)
-         ctx->ReadBuffer->Alpha = ctx->ReadBuffer->BackLeftAlpha;
-      else if (ctx->Pixel.DriverReadBuffer == GL_FRONT_RIGHT)
-         ctx->ReadBuffer->Alpha = ctx->ReadBuffer->FrontRightAlpha;
-      else
-         ctx->ReadBuffer->Alpha = ctx->ReadBuffer->BackRightAlpha;
+      /* choose the read buffer */
+      _swrast_use_read_buffer(ctx);
    }
 
    /* read source image */
@@ -176,11 +166,9 @@ copy_conv_rgba_pixels(GLcontext *ctx, GLint srcx, GLint srcy,
       }
    }
 
-   /* read from the draw buffer again (in case of blending) */
    if (changeBuffer) {
-      (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-                                    ctx->Color.DriverDrawBuffer );
-      ctx->ReadBuffer->Alpha = saveReadAlpha;
+      /* restore default src/dst buffer */
+      _swrast_use_draw_buffer(ctx);
    }
 
    /* do image transfer ops up until convolution */
@@ -301,7 +289,6 @@ copy_rgba_pixels(GLcontext *ctx, GLint srcx, GLint srcy,
    GLboolean quick_draw;
    GLint sy, dy, stepy, j;
    GLboolean changeBuffer;
-   GLchan *saveReadAlpha;
    const GLboolean zoom = ctx->Pixel.ZoomX != 1.0F || ctx->Pixel.ZoomY != 1.0F;
    GLint overlapping;
    const GLuint transferOps = ctx->_ImageTransferState;
@@ -347,13 +334,9 @@ copy_rgba_pixels(GLcontext *ctx, GLint srcx, GLint srcy,
    }
 
    /* If read and draw buffer are different we must do buffer switching */
-   saveReadAlpha = ctx->ReadBuffer->Alpha;
    changeBuffer = ctx->Pixel.ReadBuffer != ctx->Color.DrawBuffer
                   || ctx->DrawBuffer != ctx->ReadBuffer;
 
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                 ctx->Pixel.DriverReadBuffer );
-
    if (overlapping) {
       GLint ssy = sy;
       tmpImage = (GLchan *) MALLOC(width * height * sizeof(GLchan) * 4);
@@ -361,25 +344,22 @@ copy_rgba_pixels(GLcontext *ctx, GLint srcx, GLint srcy,
          _mesa_error( ctx, GL_OUT_OF_MEMORY, "glCopyPixels" );
          return;
       }
+      /* setup source */
+      if (changeBuffer)
+         _swrast_use_read_buffer(ctx);
+      /* read the source image */
       p = tmpImage;
-      if (changeBuffer) {
-         (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                       ctx->Pixel.DriverReadBuffer );
-         if (ctx->Pixel.DriverReadBuffer == GL_FRONT_LEFT)
-            ctx->ReadBuffer->Alpha = ctx->ReadBuffer->FrontLeftAlpha;
-         else if (ctx->Pixel.DriverReadBuffer == GL_BACK_LEFT)
-            ctx->ReadBuffer->Alpha = ctx->ReadBuffer->BackLeftAlpha;
-         else if (ctx->Pixel.DriverReadBuffer == GL_FRONT_RIGHT)
-            ctx->ReadBuffer->Alpha = ctx->ReadBuffer->FrontRightAlpha;
-         else
-            ctx->ReadBuffer->Alpha = ctx->ReadBuffer->BackRightAlpha;
-      }
       for (j = 0; j < height; j++, ssy += stepy) {
          _mesa_read_rgba_span( ctx, ctx->ReadBuffer, width, srcx, ssy,
                             (GLchan (*)[4]) p );
          p += width * 4;
       }
       p = tmpImage;
+      /* restore dest */
+      if (changeBuffer) {
+         _swrast_use_draw_buffer(ctx);
+         changeBuffer = GL_FALSE;
+      }
    }
    else {
       tmpImage = NULL;  /* silence compiler warnings */
@@ -395,30 +375,12 @@ copy_rgba_pixels(GLcontext *ctx, GLint srcx, GLint srcy,
       }
       else {
          /* get from framebuffer */
-         if (changeBuffer) {
-            (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                          ctx->Pixel.DriverReadBuffer );
-            if (ctx->Pixel.DriverReadBuffer == GL_FRONT_LEFT) {
-               ctx->ReadBuffer->Alpha = ctx->ReadBuffer->FrontLeftAlpha;
-            }
-            else if (ctx->Pixel.DriverReadBuffer == GL_BACK_LEFT) {
-               ctx->ReadBuffer->Alpha = ctx->ReadBuffer->BackLeftAlpha;
-            }
-            else if (ctx->Pixel.DriverReadBuffer == GL_FRONT_RIGHT) {
-               ctx->ReadBuffer->Alpha = ctx->ReadBuffer->FrontRightAlpha;
-            }
-            else {
-               ctx->ReadBuffer->Alpha = ctx->ReadBuffer->BackRightAlpha;
-            }
-         }
-         _mesa_read_rgba_span( ctx, ctx->ReadBuffer, width, srcx, sy, span->color.rgba );
-      }
-
-      if (changeBuffer) {
-         /* read from the draw buffer again (in case of blending) */
-         (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-                                       ctx->Color.DriverDrawBuffer );
-         ctx->ReadBuffer->Alpha = saveReadAlpha;
+         if (changeBuffer)
+            _swrast_use_read_buffer(ctx);
+         _mesa_read_rgba_span( ctx, ctx->ReadBuffer, width, srcx, sy,
+                               span->color.rgba );
+         if (changeBuffer)
+            _swrast_use_draw_buffer(ctx);
       }
 
       if (transferOps) {
@@ -525,10 +487,6 @@ copy_rgba_pixels(GLcontext *ctx, GLint srcx, GLint srcy,
       }
    }
 
-   /* Restore pixel source to be the draw buffer (for blending, etc) */
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-                                 ctx->Color.DriverDrawBuffer );
-
    if (overlapping)
       FREE(tmpImage);
 }
@@ -576,9 +534,6 @@ static void copy_ci_pixels( GLcontext *ctx,
    changeBuffer = ctx->Pixel.ReadBuffer != ctx->Color.DrawBuffer
                || ctx->DrawBuffer != ctx->ReadBuffer;
 
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                 ctx->Pixel.DriverReadBuffer );
-
    if (overlapping) {
       GLint ssy = sy;
       tmpImage = (GLuint *) MALLOC(width * height * sizeof(GLuint));
@@ -586,16 +541,21 @@ static void copy_ci_pixels( GLcontext *ctx,
          _mesa_error( ctx, GL_OUT_OF_MEMORY, "glCopyPixels" );
          return;
       }
+      /* setup source */
+      if (changeBuffer)
+         _swrast_use_read_buffer(ctx);
+      /* read the image */
       p = tmpImage;
-      if (changeBuffer) {
-         (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                       ctx->Pixel.DriverReadBuffer );
-      }
       for (j = 0; j < height; j++, ssy += stepy) {
          _mesa_read_index_span( ctx, ctx->ReadBuffer, width, srcx, ssy, p );
          p += width;
       }
       p = tmpImage;
+      /* restore to draw buffer */
+      if (changeBuffer) {
+         _swrast_use_draw_buffer(ctx);
+         changeBuffer = GL_FALSE;
+      }
    }
    else {
       tmpImage = NULL;  /* silence compiler warning */
@@ -608,18 +568,12 @@ static void copy_ci_pixels( GLcontext *ctx,
          p += width;
       }
       else {
-         if (changeBuffer) {
-            (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                          ctx->Pixel.DriverReadBuffer );
-         }
+         if (changeBuffer)
+            _swrast_use_read_buffer(ctx);
          _mesa_read_index_span( ctx, ctx->ReadBuffer, width, srcx, sy,
                                 span->color.index );
-      }
-
-      if (changeBuffer) {
-         /* set read buffer back to draw buffer (in case of logicops) */
-         (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-                                       ctx->Color.DriverDrawBuffer );
+         if (changeBuffer)
+            _swrast_use_draw_buffer(ctx);
       }
 
       if (shift_or_offset) {
@@ -638,10 +592,6 @@ static void copy_ci_pixels( GLcontext *ctx,
          _mesa_write_index_span(ctx, span);
    }
 
-   /* Restore pixel source to be the draw buffer (for blending, etc) */
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-                                 ctx->Color.DriverDrawBuffer );
-
    if (overlapping)
       FREE(tmpImage);
 }
diff --git a/src/mesa/swrast/s_imaging.c b/src/mesa/swrast/s_imaging.c
index 1c63f5c3416..98cbe347a72 100644
--- a/src/mesa/swrast/s_imaging.c
+++ b/src/mesa/swrast/s_imaging.c
@@ -1,4 +1,4 @@
-/* $Id: s_imaging.c,v 1.5 2002/04/04 16:53:00 brianp Exp $ */
+/* $Id: s_imaging.c,v 1.6 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -37,12 +37,10 @@ _swrast_CopyColorTable( GLcontext *ctx,
 			GLenum target, GLenum internalformat,
 			GLint x, GLint y, GLsizei width)
 {
-   SWcontext *swrast = SWRAST_CONTEXT(ctx);
    GLchan data[MAX_WIDTH][4];
 
    /* Select buffer to read from */
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                 ctx->Pixel.DriverReadBuffer );
+   _swrast_use_read_buffer(ctx);
 
    if (width > MAX_WIDTH)
       width = MAX_WIDTH;
@@ -51,8 +49,7 @@ _swrast_CopyColorTable( GLcontext *ctx,
    _mesa_read_rgba_span( ctx, ctx->ReadBuffer, width, x, y, data );
 
    /* Restore reading from draw buffer (the default) */
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-                                 ctx->Color.DriverDrawBuffer );
+   _swrast_use_draw_buffer(ctx);
 
    glColorTable(target, internalformat, width, GL_RGBA, CHAN_TYPE, data);
 }
@@ -61,12 +58,10 @@ void
 _swrast_CopyColorSubTable( GLcontext *ctx,GLenum target, GLsizei start,
 			   GLint x, GLint y, GLsizei width)
 {
-   SWcontext *swrast = SWRAST_CONTEXT(ctx);
    GLchan data[MAX_WIDTH][4];
 
    /* Select buffer to read from */
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                 ctx->Pixel.DriverReadBuffer );
+   _swrast_use_read_buffer(ctx);
 
    if (width > MAX_WIDTH)
       width = MAX_WIDTH;
@@ -75,8 +70,7 @@ _swrast_CopyColorSubTable( GLcontext *ctx,GLenum target, GLsizei start,
    _mesa_read_rgba_span( ctx, ctx->ReadBuffer, width, x, y, data );
 
    /* Restore reading from draw buffer (the default) */
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-                                 ctx->Color.DriverDrawBuffer );
+   _swrast_use_draw_buffer(ctx);
 
    glColorSubTable(target, start, width, GL_RGBA, CHAN_TYPE, data);
 }
@@ -90,6 +84,9 @@ _swrast_CopyConvolutionFilter1D(GLcontext *ctx, GLenum target,
    SWcontext *swrast = SWRAST_CONTEXT(ctx);
    GLchan rgba[MAX_CONVOLUTION_WIDTH][4];
 
+   /* Select buffer to read from */
+   _swrast_use_read_buffer(ctx);
+
    RENDER_START( swrast, ctx );
 
    /* read the data from framebuffer */
@@ -98,6 +95,9 @@ _swrast_CopyConvolutionFilter1D(GLcontext *ctx, GLenum target,
    
    RENDER_FINISH( swrast, ctx );
 
+   /* Restore reading from draw buffer (the default) */
+   _swrast_use_draw_buffer(ctx);
+
    /* store as convolution filter */
    glConvolutionFilter1D(target, internalFormat, width,
 			 GL_RGBA, CHAN_TYPE, rgba);
@@ -114,6 +114,9 @@ _swrast_CopyConvolutionFilter2D(GLcontext *ctx, GLenum target,
    GLchan rgba[MAX_CONVOLUTION_HEIGHT][MAX_CONVOLUTION_WIDTH][4];
    GLint i;
 
+   /* Select buffer to read from */
+   _swrast_use_read_buffer(ctx);
+
    RENDER_START(swrast,ctx);
    
    /* read pixels from framebuffer */
@@ -124,6 +127,9 @@ _swrast_CopyConvolutionFilter2D(GLcontext *ctx, GLenum target,
 
    RENDER_FINISH(swrast,ctx);
 
+   /* Restore reading from draw buffer (the default) */
+   _swrast_use_draw_buffer(ctx);
+
    /*
     * HACK: save & restore context state so we can store this as a
     * convolution filter via the GL api.  Doesn't call any callbacks
diff --git a/src/mesa/swrast/s_readpix.c b/src/mesa/swrast/s_readpix.c
index a52cd8e7c0b..f925e791162 100644
--- a/src/mesa/swrast/s_readpix.c
+++ b/src/mesa/swrast/s_readpix.c
@@ -1,4 +1,4 @@
-/* $Id: s_readpix.c,v 1.14 2002/04/19 00:38:27 brianp Exp $ */
+/* $Id: s_readpix.c,v 1.15 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -62,9 +62,7 @@ read_index_pixels( GLcontext *ctx,
       return;
    }
 
-   ASSERT(swrast->Driver.SetReadBuffer);
-   (*swrast->Driver.SetReadBuffer)(ctx, ctx->ReadBuffer,
-                                ctx->Pixel.DriverReadBuffer);
+   _swrast_use_read_buffer(ctx);
 
    readWidth = (width > MAX_WIDTH) ? MAX_WIDTH : width;
 
@@ -82,8 +80,7 @@ read_index_pixels( GLcontext *ctx,
                             &ctx->Pack, ctx->_ImageTransferState);
    }
 
-   (*swrast->Driver.SetReadBuffer)(ctx, ctx->DrawBuffer,
-                                ctx->Color.DriverDrawBuffer);
+   _swrast_use_draw_buffer(ctx);
 }
 
 
@@ -318,13 +315,13 @@ read_rgba_pixels( GLcontext *ctx,
    SWcontext *swrast = SWRAST_CONTEXT(ctx);
    GLint readWidth;
 
-   (*swrast->Driver.SetReadBuffer)(ctx, ctx->ReadBuffer, ctx->Pixel.DriverReadBuffer);
+   _swrast_use_read_buffer(ctx);
 
    /* Try optimized path first */
    if (read_fast_rgba_pixels( ctx, x, y, width, height,
                               format, type, pixels, packing )) {
 
-      (*swrast->Driver.SetReadBuffer)(ctx, ctx->DrawBuffer, ctx->Color.DriverDrawBuffer);
+      _swrast_use_draw_buffer(ctx);
       return; /* done! */
    }
 
@@ -470,7 +467,7 @@ read_rgba_pixels( GLcontext *ctx,
       }
    }
 
-   (*swrast->Driver.SetReadBuffer)(ctx, ctx->DrawBuffer, ctx->Color.DriverDrawBuffer);
+   _swrast_use_draw_buffer(ctx);
 }
 
 
diff --git a/src/mesa/swrast/s_span.c b/src/mesa/swrast/s_span.c
index a3271d7806d..94cd4a9ce83 100644
--- a/src/mesa/swrast/s_span.c
+++ b/src/mesa/swrast/s_span.c
@@ -1,4 +1,4 @@
-/* $Id: s_span.c,v 1.44 2002/06/15 03:03:11 brianp Exp $ */
+/* $Id: s_span.c,v 1.45 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -608,19 +608,19 @@ multi_write_index_span( GLcontext *ctx, struct sw_span *span )
    GLuint bufferBit;
 
    /* loop over four possible dest color buffers */
-   for (bufferBit = 1; bufferBit <= 8; bufferBit = bufferBit << 1) {
-      if (bufferBit & ctx->Color.DrawDestMask) {
+   for (bufferBit = 1; bufferBit <= 8; bufferBit <<= 1) {
+      if (bufferBit & ctx->Color._DrawDestMask) {
          GLuint indexTmp[MAX_WIDTH];
          ASSERT(span->end < MAX_WIDTH);
 
          if (bufferBit == FRONT_LEFT_BIT)
-            (void) (*ctx->Driver.SetDrawBuffer)( ctx, GL_FRONT_LEFT);
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_FRONT_LEFT);
          else if (bufferBit == FRONT_RIGHT_BIT)
-            (void) (*ctx->Driver.SetDrawBuffer)( ctx, GL_FRONT_RIGHT);
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_FRONT_RIGHT);
          else if (bufferBit == BACK_LEFT_BIT)
-            (void) (*ctx->Driver.SetDrawBuffer)( ctx, GL_BACK_LEFT);
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_BACK_LEFT);
          else
-            (void) (*ctx->Driver.SetDrawBuffer)( ctx, GL_BACK_RIGHT);
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_BACK_RIGHT);
 
          /* make copy of incoming indexes */
          MEMCPY( indexTmp, span->color.index, span->end * sizeof(GLuint) );
@@ -648,7 +648,7 @@ multi_write_index_span( GLcontext *ctx, struct sw_span *span )
    }
 
    /* restore default dest buffer */
-   (void) (*ctx->Driver.SetDrawBuffer)( ctx, ctx->Color.DriverDrawBuffer);
+   _swrast_use_draw_buffer(ctx);
 }
 
 
@@ -670,26 +670,26 @@ multi_write_rgba_span( GLcontext *ctx, struct sw_span *span )
       return;
 
    /* loop over four possible dest color buffers */
-   for (bufferBit = 1; bufferBit <= 8; bufferBit = bufferBit << 1) {
-      if (bufferBit & ctx->Color.DrawDestMask) {
+   for (bufferBit = 1; bufferBit <= 8; bufferBit <<= 1) {
+      if (bufferBit & ctx->Color._DrawDestMask) {
          GLchan rgbaTmp[MAX_WIDTH][4];
          ASSERT(span->end < MAX_WIDTH);
 
          if (bufferBit == FRONT_LEFT_BIT) {
-            (void) (*ctx->Driver.SetDrawBuffer)( ctx, GL_FRONT_LEFT);
-            ctx->DrawBuffer->Alpha = ctx->DrawBuffer->FrontLeftAlpha;
+            ctx->Color._DriverDrawBuffer = GL_FRONT_LEFT;
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_FRONT_LEFT);
          }
          else if (bufferBit == FRONT_RIGHT_BIT) {
-            (void) (*ctx->Driver.SetDrawBuffer)( ctx, GL_FRONT_RIGHT);
-            ctx->DrawBuffer->Alpha = ctx->DrawBuffer->FrontRightAlpha;
+            ctx->Color._DriverDrawBuffer = GL_FRONT_RIGHT;
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_FRONT_RIGHT);
          }
          else if (bufferBit == BACK_LEFT_BIT) {
-            (void) (*ctx->Driver.SetDrawBuffer)( ctx, GL_BACK_LEFT);
-            ctx->DrawBuffer->Alpha = ctx->DrawBuffer->BackLeftAlpha;
+            ctx->Color._DriverDrawBuffer = GL_BACK_LEFT;
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_BACK_LEFT);
          }
          else {
-            (void) (*ctx->Driver.SetDrawBuffer)( ctx, GL_BACK_RIGHT);
-            ctx->DrawBuffer->Alpha = ctx->DrawBuffer->BackRightAlpha;
+            ctx->Color._DriverDrawBuffer = GL_BACK_RIGHT;
+            (*swrast->Driver.SetBuffer)(ctx, ctx->DrawBuffer, GL_BACK_RIGHT);
          }
 
          /* make copy of incoming colors */
@@ -734,7 +734,7 @@ multi_write_rgba_span( GLcontext *ctx, struct sw_span *span )
    }
 
    /* restore default dest buffer */
-   (void) (*ctx->Driver.SetDrawBuffer)( ctx, ctx->Color.DriverDrawBuffer );
+   _swrast_use_draw_buffer(ctx);
 }
 
 
diff --git a/src/mesa/swrast/s_texstore.c b/src/mesa/swrast/s_texstore.c
index e1adeded7fc..88fe786ef8c 100644
--- a/src/mesa/swrast/s_texstore.c
+++ b/src/mesa/swrast/s_texstore.c
@@ -1,4 +1,4 @@
-/* $Id: s_texstore.c,v 1.5 2001/05/21 16:41:04 brianp Exp $ */
+/* $Id: s_texstore.c,v 1.6 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -73,8 +73,7 @@ read_color_image( GLcontext *ctx, GLint x, GLint y,
       return NULL;
 
    /* Select buffer to read from */
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->ReadBuffer,
-                                 ctx->Pixel.DriverReadBuffer );
+   _swrast_use_read_buffer(ctx);
 
    RENDER_START(swrast,ctx);
 
@@ -89,8 +88,7 @@ read_color_image( GLcontext *ctx, GLint x, GLint y,
    RENDER_FINISH(swrast,ctx);
 
    /* Read from draw buffer (the default) */
-   (*swrast->Driver.SetReadBuffer)( ctx, ctx->DrawBuffer,
-                                 ctx->Color.DriverDrawBuffer );
+   _swrast_use_draw_buffer(ctx);
 
    return image;
 }
diff --git a/src/mesa/swrast/s_triangle.c b/src/mesa/swrast/s_triangle.c
index bdbdde76b83..634664371bd 100644
--- a/src/mesa/swrast/s_triangle.c
+++ b/src/mesa/swrast/s_triangle.c
@@ -1,4 +1,4 @@
-/* $Id: s_triangle.c,v 1.59 2002/06/15 03:03:12 brianp Exp $ */
+/* $Id: s_triangle.c,v 1.60 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -218,7 +218,7 @@ static void simple_textured_triangle( GLcontext *ctx,
       span->intTex[1] += span->intTexStep[1];				\
    }									\
    (*swrast->Driver.WriteRGBSpan)(ctx, span->end, span->x, span->y,	\
-                                  (CONST GLchan (*)[3]) span->color.rgb,	\
+                                  (CONST GLchan (*)[3]) span->color.rgb,\
                                   NULL );
 
 #include "s_tritemp.h"
@@ -283,7 +283,7 @@ static void simple_z_textured_triangle( GLcontext *ctx,
       span->z += span->zStep;						\
    }									\
    (*swrast->Driver.WriteRGBSpan)(ctx, span->end, span->x, span->y,	\
-                                  (CONST GLchan (*)[3]) span->color.rgb,	\
+                                  (CONST GLchan (*)[3]) span->color.rgb,\
                                   span->mask );
 
 #include "s_tritemp.h"
@@ -589,7 +589,7 @@ static void affine_textured_triangle( GLcontext *ctx,
    info.format = obj->Image[b]->Format;					\
    info.filter = obj->MinFilter;					\
    info.envmode = unit->EnvMode;					\
-   span->arrayMask |= SPAN_RGBA;						\
+   span->arrayMask |= SPAN_RGBA;					\
 									\
    if (info.envmode == GL_BLEND) {					\
       /* potential off-by-one error here? (1.0f -> 2048 -> 0) */	\
@@ -896,7 +896,7 @@ static void persp_textured_triangle( GLcontext *ctx,
 
 #define RENDER_SPAN( span )			\
    span->interpMask &= ~SPAN_RGBA;		\
-   span->arrayMask |= SPAN_RGBA;			\
+   span->arrayMask |= SPAN_RGBA;		\
    fast_persp_span(ctx, span, &info);
 
 #include "s_tritemp.h"
@@ -976,7 +976,7 @@ static void occlusion_zless_triangle( GLcontext *ctx,
 #define RENDER_SPAN( span )				\
    GLuint i;						\
    for (i = 0; i < span->end; i++) {			\
-      GLdepth z = FixedToDepth(span->z);			\
+      GLdepth z = FixedToDepth(span->z);		\
       if (z < zRow[i]) {				\
          ctx->OcclusionResult = GL_TRUE;		\
          return;					\
diff --git a/src/mesa/swrast/swrast.h b/src/mesa/swrast/swrast.h
index f36031cfb4a..a33e97ec017 100644
--- a/src/mesa/swrast/swrast.h
+++ b/src/mesa/swrast/swrast.h
@@ -1,4 +1,4 @@
-/* $Id: swrast.h,v 1.24 2002/04/19 14:05:50 brianp Exp $ */
+/* $Id: swrast.h,v 1.25 2002/07/09 01:22:52 brianp Exp $ */
 
 /*
  * Mesa 3-D graphics library
@@ -204,6 +204,12 @@ struct swrast_device_driver;
 extern void
 _swrast_alloc_buffers( GLframebuffer *buffer );
 
+extern void
+_swrast_use_read_buffer( GLcontext *ctx );
+
+extern void
+_swrast_use_draw_buffer( GLcontext *ctx );
+
 extern GLboolean
 _swrast_CreateContext( GLcontext *ctx );
 
@@ -254,6 +260,10 @@ _swrast_Accum( GLcontext *ctx, GLenum op,
 	       GLint width, GLint height );
 
 
+extern void
+_swrast_DrawBuffer( GLcontext *ctx, GLenum mode );
+
+
 /* Reset the stipple counter
  */
 extern void
@@ -363,11 +373,14 @@ _swrast_copy_texsubimage3d(GLcontext *ctx,
  */
 struct swrast_device_driver {
 
-   void (*SetReadBuffer)( GLcontext *ctx, GLframebuffer *colorBuffer,
-                          GLenum buffer );
+   void (*SetBuffer)( GLcontext *ctx, GLframebuffer *buffer,
+                      GLenum colorBuffer );
    /*
-    * Specifies the current buffer for span/pixel reading.
-    * colorBuffer will be one of:
+    * Specifies the current buffer for span/pixel writing/reading.
+    * buffer indicates which window to write to / read from.  Normally,
+    * this'll be the buffer currently bound to the context, but it doesn't
+    * have to be!
+    * colorBuffer indicates which color buffer, one of:
     *    GL_FRONT_LEFT - this buffer always exists
     *    GL_BACK_LEFT - when double buffering
     *    GL_FRONT_RIGHT - when using stereo