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authorBrian Paul <brian.paul@tungstengraphics.com>2000-10-19 18:09:01 +0000
committerBrian Paul <brian.paul@tungstengraphics.com>2000-10-19 18:09:01 +0000
commitceab2285405c1ed7aca2d7fbb8a39c5f82a12117 (patch)
tree8dc9a2ebe99908cd0d7e9304a11bb22557ddfd71
parent03614d2f33f4e970a18b8c240f236df46ea68fb9 (diff)
improved blending accuracy to fix Glean test failures
-rw-r--r--src/mesa/main/blend.c58
1 files changed, 39 insertions, 19 deletions
diff --git a/src/mesa/main/blend.c b/src/mesa/main/blend.c
index 5924585f3f3..a4a41cab2b4 100644
--- a/src/mesa/main/blend.c
+++ b/src/mesa/main/blend.c
@@ -1,10 +1,10 @@
-/* $Id: blend.c,v 1.16 2000/06/29 22:06:22 brianp Exp $ */
+/* $Id: blend.c,v 1.16.4.1 2000/10/19 18:09:01 brianp Exp $ */
/*
* Mesa 3-D graphics library
- * Version: 3.3
+ * Version: 3.4
*
- * Copyright (C) 1999 Brian Paul All Rights Reserved.
+ * Copyright (C) 1999-2000 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
@@ -339,11 +339,31 @@ blend_transparency( GLcontext *ctx, GLuint n, const GLubyte mask[],
/* 100% alpha, no-op */
}
else {
+#if 0
+ /* This is pretty close, but Glean complains */
const GLint s = CHAN_MAX - t;
- const GLint r = (rgba[i][RCOMP] * t + dest[i][RCOMP] * s) >> 8;
- const GLint g = (rgba[i][GCOMP] * t + dest[i][GCOMP] * s) >> 8;
- const GLint b = (rgba[i][BCOMP] * t + dest[i][BCOMP] * s) >> 8;
- const GLint a = (rgba[i][ACOMP] * t + dest[i][ACOMP] * s) >> 8;
+ const GLint r = (rgba[i][RCOMP] * t + dest[i][RCOMP] * s + 1) >> 8;
+ const GLint g = (rgba[i][GCOMP] * t + dest[i][GCOMP] * s + 1) >> 8;
+ const GLint b = (rgba[i][BCOMP] * t + dest[i][BCOMP] * s + 1) >> 8;
+ const GLint a = (rgba[i][ACOMP] * t + dest[i][ACOMP] * s + 1) >> 8;
+#elif 0
+ /* This is slower but satisfies Glean */
+ const GLint s = CHAN_MAX - t;
+ const GLint r = (rgba[i][RCOMP] * t + dest[i][RCOMP] * s) / 255;
+ const GLint g = (rgba[i][GCOMP] * t + dest[i][GCOMP] * s) / 255;
+ const GLint b = (rgba[i][BCOMP] * t + dest[i][BCOMP] * s) / 255;
+ const GLint a = (rgba[i][ACOMP] * t + dest[i][ACOMP] * s) / 255;
+#else
+ /* This satisfies Glean and should be reasonably fast */
+ /* Contributed by Nathan Hand */
+#define DIV255(X) (((X) << 8) + (X) + 256) >> 16
+ const GLint s = CHAN_MAX - t;
+ const GLint r = DIV255(rgba[i][RCOMP] * t + dest[i][RCOMP] * s);
+ const GLint g = DIV255(rgba[i][GCOMP] * t + dest[i][GCOMP] * s);
+ const GLint b = DIV255(rgba[i][BCOMP] * t + dest[i][BCOMP] * s);
+ const GLint a = DIV255(rgba[i][ACOMP] * t + dest[i][ACOMP] * s);
+#undef DIV255
+#endif
ASSERT(r <= CHAN_MAX);
ASSERT(g <= CHAN_MAX);
ASSERT(b <= CHAN_MAX);
@@ -755,22 +775,22 @@ blend_general( GLcontext *ctx, GLuint n, const GLubyte mask[],
/* compute blended color */
if (ctx->Color.BlendEquation==GL_FUNC_ADD_EXT) {
- r = Rs * sR + Rd * dR;
- g = Gs * sG + Gd * dG;
- b = Bs * sB + Bd * dB;
- a = As * sA + Ad * dA;
+ r = Rs * sR + Rd * dR + 0.5F;
+ g = Gs * sG + Gd * dG + 0.5F;
+ b = Bs * sB + Bd * dB + 0.5F;
+ a = As * sA + Ad * dA + 0.5F;
}
else if (ctx->Color.BlendEquation==GL_FUNC_SUBTRACT_EXT) {
- r = Rs * sR - Rd * dR;
- g = Gs * sG - Gd * dG;
- b = Bs * sB - Bd * dB;
- a = As * sA - Ad * dA;
+ r = Rs * sR - Rd * dR + 0.5F;
+ g = Gs * sG - Gd * dG + 0.5F;
+ b = Bs * sB - Bd * dB + 0.5F;
+ a = As * sA - Ad * dA + 0.5F;
}
else if (ctx->Color.BlendEquation==GL_FUNC_REVERSE_SUBTRACT_EXT) {
- r = Rd * dR - Rs * sR;
- g = Gd * dG - Gs * sG;
- b = Bd * dB - Bs * sB;
- a = Ad * dA - As * sA;
+ r = Rd * dR - Rs * sR + 0.5F;
+ g = Gd * dG - Gs * sG + 0.5F;
+ b = Bd * dB - Bs * sB + 0.5F;
+ a = Ad * dA - As * sA + 0.5F;
}
else {
/* should never get here */