/* * Mesa 3-D graphics library * * Copyright (C) 1999-2006 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"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. */ #include "main/glheader.h" #include "main/colormac.h" #include "main/macros.h" #include "s_context.h" #include "s_fog.h" /** * Used to convert current raster distance to a fog factor in [0,1]. */ GLfloat _swrast_z_to_fogfactor(struct gl_context *ctx, GLfloat z) { GLfloat d, f; switch (ctx->Fog.Mode) { case GL_LINEAR: if (ctx->Fog.Start == ctx->Fog.End) d = 1.0F; else d = 1.0F / (ctx->Fog.End - ctx->Fog.Start); f = (ctx->Fog.End - z) * d; return CLAMP(f, 0.0F, 1.0F); case GL_EXP: d = ctx->Fog.Density; f = EXPF(-d * z); f = CLAMP(f, 0.0F, 1.0F); return f; case GL_EXP2: d = ctx->Fog.Density; f = EXPF(-(d * d * z * z)); f = CLAMP(f, 0.0F, 1.0F); return f; default: _mesa_problem(ctx, "Bad fog mode in _swrast_z_to_fogfactor"); return 0.0; } } #define LINEAR_FOG(f, coord) f = (fogEnd - coord) * fogScale #define EXP_FOG(f, coord) f = EXPF(density * coord) #define EXP2_FOG(f, coord) \ do { \ GLfloat tmp = negDensitySquared * coord * coord; \ if (tmp < FLT_MIN_10_EXP) \ tmp = FLT_MIN_10_EXP; \ f = EXPF(tmp); \ } while(0) #define BLEND_FOG(f, coord) f = coord /** * Template code for computing fog blend factor and applying it to colors. * \param TYPE either GLubyte, GLushort or GLfloat. * \param COMPUTE_F code to compute the fog blend factor, f. */ #define FOG_LOOP(TYPE, FOG_FUNC) \ if (span->arrayAttribs & VARYING_BIT_FOGC) { \ GLuint i; \ for (i = 0; i < span->end; i++) { \ const GLfloat fogCoord = span->array->attribs[VARYING_SLOT_FOGC][i][0]; \ const GLfloat c = FABSF(fogCoord); \ GLfloat f, oneMinusF; \ FOG_FUNC(f, c); \ f = CLAMP(f, 0.0F, 1.0F); \ oneMinusF = 1.0F - f; \ rgba[i][RCOMP] = (TYPE) (f * rgba[i][RCOMP] + oneMinusF * rFog); \ rgba[i][GCOMP] = (TYPE) (f * rgba[i][GCOMP] + oneMinusF * gFog); \ rgba[i][BCOMP] = (TYPE) (f * rgba[i][BCOMP] + oneMinusF * bFog); \ } \ } \ else { \ const GLfloat fogStep = span->attrStepX[VARYING_SLOT_FOGC][0]; \ GLfloat fogCoord = span->attrStart[VARYING_SLOT_FOGC][0]; \ const GLfloat wStep = span->attrStepX[VARYING_SLOT_POS][3]; \ GLfloat w = span->attrStart[VARYING_SLOT_POS][3]; \ GLuint i; \ for (i = 0; i < span->end; i++) { \ const GLfloat c = FABSF(fogCoord) / w; \ GLfloat f, oneMinusF; \ FOG_FUNC(f, c); \ f = CLAMP(f, 0.0F, 1.0F); \ oneMinusF = 1.0F - f; \ rgba[i][RCOMP] = (TYPE) (f * rgba[i][RCOMP] + oneMinusF * rFog); \ rgba[i][GCOMP] = (TYPE) (f * rgba[i][GCOMP] + oneMinusF * gFog); \ rgba[i][BCOMP] = (TYPE) (f * rgba[i][BCOMP] + oneMinusF * bFog); \ fogCoord += fogStep; \ w += wStep; \ } \ } /** * Apply fog to a span of RGBA pixels. * The fog value are either in the span->array->fog array or interpolated from * the fog/fogStep values. * They fog values are either fog coordinates (Z) or fog blend factors. * _PreferPixelFog should be in sync with that state! */ void _swrast_fog_rgba_span( const struct gl_context *ctx, SWspan *span ) { const SWcontext *swrast = CONST_SWRAST_CONTEXT(ctx); GLfloat rFog, gFog, bFog; ASSERT(swrast->_FogEnabled); ASSERT(span->arrayMask & SPAN_RGBA); /* compute (scaled) fog color */ if (span->array->ChanType == GL_UNSIGNED_BYTE) { rFog = ctx->Fog.Color[RCOMP] * 255.0F; gFog = ctx->Fog.Color[GCOMP] * 255.0F; bFog = ctx->Fog.Color[BCOMP] * 255.0F; } else if (span->array->ChanType == GL_UNSIGNED_SHORT) { rFog = ctx->Fog.Color[RCOMP] * 65535.0F; gFog = ctx->Fog.Color[GCOMP] * 65535.0F; bFog = ctx->Fog.Color[BCOMP] * 65535.0F; } else { rFog = ctx->Fog.Color[RCOMP]; gFog = ctx->Fog.Color[GCOMP]; bFog = ctx->Fog.Color[BCOMP]; } if (swrast->_PreferPixelFog) { /* The span's fog values are fog coordinates, now compute blend factors * and blend the fragment colors with the fog color. */ switch (ctx->Fog.Mode) { case GL_LINEAR: { const GLfloat fogEnd = ctx->Fog.End; const GLfloat fogScale = (ctx->Fog.Start == ctx->Fog.End) ? 1.0F : 1.0F / (ctx->Fog.End - ctx->Fog.Start); if (span->array->ChanType == GL_UNSIGNED_BYTE) { GLubyte (*rgba)[4] = span->array->rgba8; FOG_LOOP(GLubyte, LINEAR_FOG); } else if (span->array->ChanType == GL_UNSIGNED_SHORT) { GLushort (*rgba)[4] = span->array->rgba16; FOG_LOOP(GLushort, LINEAR_FOG); } else { GLfloat (*rgba)[4] = span->array->attribs[VARYING_SLOT_COL0]; ASSERT(span->array->ChanType == GL_FLOAT); FOG_LOOP(GLfloat, LINEAR_FOG); } } break; case GL_EXP: { const GLfloat density = -ctx->Fog.Density; if (span->array->ChanType == GL_UNSIGNED_BYTE) { GLubyte (*rgba)[4] = span->array->rgba8; FOG_LOOP(GLubyte, EXP_FOG); } else if (span->array->ChanType == GL_UNSIGNED_SHORT) { GLushort (*rgba)[4] = span->array->rgba16; FOG_LOOP(GLushort, EXP_FOG); } else { GLfloat (*rgba)[4] = span->array->attribs[VARYING_SLOT_COL0]; ASSERT(span->array->ChanType == GL_FLOAT); FOG_LOOP(GLfloat, EXP_FOG); } } break; case GL_EXP2: { const GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density; if (span->array->ChanType == GL_UNSIGNED_BYTE) { GLubyte (*rgba)[4] = span->array->rgba8; FOG_LOOP(GLubyte, EXP2_FOG); } else if (span->array->ChanType == GL_UNSIGNED_SHORT) { GLushort (*rgba)[4] = span->array->rgba16; FOG_LOOP(GLushort, EXP2_FOG); } else { GLfloat (*rgba)[4] = span->array->attribs[VARYING_SLOT_COL0]; ASSERT(span->array->ChanType == GL_FLOAT); FOG_LOOP(GLfloat, EXP2_FOG); } } break; default: _mesa_problem(ctx, "Bad fog mode in _swrast_fog_rgba_span"); return; } } else { /* The span's fog start/step/array values are blend factors in [0,1]. * They were previously computed per-vertex. */ if (span->array->ChanType == GL_UNSIGNED_BYTE) { GLubyte (*rgba)[4] = span->array->rgba8; FOG_LOOP(GLubyte, BLEND_FOG); } else if (span->array->ChanType == GL_UNSIGNED_SHORT) { GLushort (*rgba)[4] = span->array->rgba16; FOG_LOOP(GLushort, BLEND_FOG); } else { GLfloat (*rgba)[4] = span->array->attribs[VARYING_SLOT_COL0]; ASSERT(span->array->ChanType == GL_FLOAT); FOG_LOOP(GLfloat, BLEND_FOG); } } }