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238 lines
8.1 KiB
C
238 lines
8.1 KiB
C
/*
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* Mesa 3-D graphics library
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* Version: 6.5.2
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*
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* Copyright (C) 1999-2006 Brian Paul All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include <precomp.h>
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/**
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* Used to convert current raster distance to a fog factor in [0,1].
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*/
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GLfloat
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_swrast_z_to_fogfactor(struct gl_context *ctx, GLfloat z)
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{
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GLfloat d, f;
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switch (ctx->Fog.Mode) {
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case GL_LINEAR:
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if (ctx->Fog.Start == ctx->Fog.End)
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d = 1.0F;
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else
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d = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
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f = (ctx->Fog.End - z) * d;
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return CLAMP(f, 0.0F, 1.0F);
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case GL_EXP:
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d = ctx->Fog.Density;
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f = EXPF(-d * z);
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f = CLAMP(f, 0.0F, 1.0F);
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return f;
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case GL_EXP2:
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d = ctx->Fog.Density;
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f = EXPF(-(d * d * z * z));
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f = CLAMP(f, 0.0F, 1.0F);
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return f;
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default:
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_mesa_problem(ctx, "Bad fog mode in _swrast_z_to_fogfactor");
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return 0.0;
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}
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}
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#define LINEAR_FOG(f, coord) f = (fogEnd - coord) * fogScale
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#define EXP_FOG(f, coord) f = EXPF(density * coord)
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#define EXP2_FOG(f, coord) \
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do { \
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GLfloat tmp = negDensitySquared * coord * coord; \
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if (tmp < FLT_MIN_10_EXP) \
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tmp = FLT_MIN_10_EXP; \
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f = EXPF(tmp); \
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} while(0)
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#define BLEND_FOG(f, coord) f = coord
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/**
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* Template code for computing fog blend factor and applying it to colors.
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* \param TYPE either GLubyte, GLushort or GLfloat.
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* \param COMPUTE_F code to compute the fog blend factor, f.
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*/
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#define FOG_LOOP(TYPE, FOG_FUNC) \
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if (span->arrayAttribs & FRAG_BIT_FOGC) { \
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GLuint i; \
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for (i = 0; i < span->end; i++) { \
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const GLfloat fogCoord = span->array->attribs[FRAG_ATTRIB_FOGC][i][0]; \
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const GLfloat c = FABSF(fogCoord); \
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GLfloat f, oneMinusF; \
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FOG_FUNC(f, c); \
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f = CLAMP(f, 0.0F, 1.0F); \
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oneMinusF = 1.0F - f; \
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rgba[i][RCOMP] = (TYPE) (f * rgba[i][RCOMP] + oneMinusF * rFog); \
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rgba[i][GCOMP] = (TYPE) (f * rgba[i][GCOMP] + oneMinusF * gFog); \
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rgba[i][BCOMP] = (TYPE) (f * rgba[i][BCOMP] + oneMinusF * bFog); \
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} \
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} \
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else { \
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const GLfloat fogStep = span->attrStepX[FRAG_ATTRIB_FOGC][0]; \
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GLfloat fogCoord = span->attrStart[FRAG_ATTRIB_FOGC][0]; \
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const GLfloat wStep = span->attrStepX[FRAG_ATTRIB_WPOS][3]; \
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GLfloat w = span->attrStart[FRAG_ATTRIB_WPOS][3]; \
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GLuint i; \
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for (i = 0; i < span->end; i++) { \
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const GLfloat c = FABSF(fogCoord) / w; \
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GLfloat f, oneMinusF; \
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FOG_FUNC(f, c); \
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f = CLAMP(f, 0.0F, 1.0F); \
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oneMinusF = 1.0F - f; \
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rgba[i][RCOMP] = (TYPE) (f * rgba[i][RCOMP] + oneMinusF * rFog); \
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rgba[i][GCOMP] = (TYPE) (f * rgba[i][GCOMP] + oneMinusF * gFog); \
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rgba[i][BCOMP] = (TYPE) (f * rgba[i][BCOMP] + oneMinusF * bFog); \
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fogCoord += fogStep; \
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w += wStep; \
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} \
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}
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/**
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* Apply fog to a span of RGBA pixels.
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* The fog value are either in the span->array->fog array or interpolated from
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* the fog/fogStep values.
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* They fog values are either fog coordinates (Z) or fog blend factors.
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* _PreferPixelFog should be in sync with that state!
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*/
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void
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_swrast_fog_rgba_span( const struct gl_context *ctx, SWspan *span )
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{
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const SWcontext *swrast = CONST_SWRAST_CONTEXT(ctx);
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GLfloat rFog, gFog, bFog;
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ASSERT(swrast->_FogEnabled);
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ASSERT(span->arrayMask & SPAN_RGBA);
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/* compute (scaled) fog color */
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if (span->array->ChanType == GL_UNSIGNED_BYTE) {
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rFog = ctx->Fog.Color[RCOMP] * 255.0F;
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gFog = ctx->Fog.Color[GCOMP] * 255.0F;
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bFog = ctx->Fog.Color[BCOMP] * 255.0F;
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}
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else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
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rFog = ctx->Fog.Color[RCOMP] * 65535.0F;
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gFog = ctx->Fog.Color[GCOMP] * 65535.0F;
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bFog = ctx->Fog.Color[BCOMP] * 65535.0F;
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}
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else {
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rFog = ctx->Fog.Color[RCOMP];
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gFog = ctx->Fog.Color[GCOMP];
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bFog = ctx->Fog.Color[BCOMP];
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}
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if (swrast->_PreferPixelFog) {
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/* The span's fog values are fog coordinates, now compute blend factors
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* and blend the fragment colors with the fog color.
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*/
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switch (ctx->Fog.Mode) {
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case GL_LINEAR:
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{
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const GLfloat fogEnd = ctx->Fog.End;
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const GLfloat fogScale = (ctx->Fog.Start == ctx->Fog.End)
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? 1.0F : 1.0F / (ctx->Fog.End - ctx->Fog.Start);
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if (span->array->ChanType == GL_UNSIGNED_BYTE) {
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GLubyte (*rgba)[4] = span->array->rgba8;
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FOG_LOOP(GLubyte, LINEAR_FOG);
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}
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else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
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GLushort (*rgba)[4] = span->array->rgba16;
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FOG_LOOP(GLushort, LINEAR_FOG);
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}
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else {
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GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL];
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ASSERT(span->array->ChanType == GL_FLOAT);
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FOG_LOOP(GLfloat, LINEAR_FOG);
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}
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}
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break;
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case GL_EXP:
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{
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const GLfloat density = -ctx->Fog.Density;
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if (span->array->ChanType == GL_UNSIGNED_BYTE) {
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GLubyte (*rgba)[4] = span->array->rgba8;
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FOG_LOOP(GLubyte, EXP_FOG);
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}
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else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
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GLushort (*rgba)[4] = span->array->rgba16;
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FOG_LOOP(GLushort, EXP_FOG);
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}
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else {
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GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL];
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ASSERT(span->array->ChanType == GL_FLOAT);
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FOG_LOOP(GLfloat, EXP_FOG);
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}
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}
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break;
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case GL_EXP2:
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{
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const GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
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if (span->array->ChanType == GL_UNSIGNED_BYTE) {
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GLubyte (*rgba)[4] = span->array->rgba8;
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FOG_LOOP(GLubyte, EXP2_FOG);
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}
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else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
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GLushort (*rgba)[4] = span->array->rgba16;
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FOG_LOOP(GLushort, EXP2_FOG);
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}
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else {
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GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL];
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ASSERT(span->array->ChanType == GL_FLOAT);
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FOG_LOOP(GLfloat, EXP2_FOG);
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}
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}
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break;
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default:
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_mesa_problem(ctx, "Bad fog mode in _swrast_fog_rgba_span");
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return;
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}
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}
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else {
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/* The span's fog start/step/array values are blend factors in [0,1].
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* They were previously computed per-vertex.
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*/
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if (span->array->ChanType == GL_UNSIGNED_BYTE) {
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GLubyte (*rgba)[4] = span->array->rgba8;
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FOG_LOOP(GLubyte, BLEND_FOG);
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}
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else if (span->array->ChanType == GL_UNSIGNED_SHORT) {
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GLushort (*rgba)[4] = span->array->rgba16;
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FOG_LOOP(GLushort, BLEND_FOG);
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}
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else {
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GLfloat (*rgba)[4] = span->array->attribs[FRAG_ATTRIB_COL];
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ASSERT(span->array->ChanType == GL_FLOAT);
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FOG_LOOP(GLfloat, BLEND_FOG);
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}
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}
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}
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