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Diffstat (limited to 'src/mesa/swrast/s_fog.c')
| -rw-r--r-- | src/mesa/swrast/s_fog.c | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/src/mesa/swrast/s_fog.c b/src/mesa/swrast/s_fog.c new file mode 100644 index 0000000000..f4c3fe4f2d --- /dev/null +++ b/src/mesa/swrast/s_fog.c @@ -0,0 +1,384 @@ +/* + * Mesa 3-D graphics library + * Version: 6.5.2 + * + * 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 + * BRIAN PAUL 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 "glheader.h" +#include "colormac.h" +#include "context.h" +#include "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(GLcontext *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; + } +} + + +/** + * 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, COMPUTE_F) \ +do { \ + const GLfloat fogStep = span->fogStep; \ + GLfloat fogCoord = span->fog; \ + const GLfloat wStep = haveW ? span->dwdx : 0.0F; \ + GLfloat w = haveW ? span->w : 1.0F; \ + GLuint i; \ + for (i = 0; i < span->end; i++) { \ + GLfloat f, oneMinusF; \ + COMPUTE_F; \ + 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; \ + } \ +} while (0) + + + +/** + * 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 GLcontext *ctx, SWspan *span ) +{ + const SWcontext *swrast = SWRAST_CONTEXT(ctx); + GLfloat rFog, gFog, bFog; + const GLuint haveW = (span->interpMask & SPAN_W); + + ASSERT(swrast->_FogEnabled); + ASSERT((span->interpMask | span->arrayMask) & SPAN_FOG); + ASSERT(span->arrayMask & SPAN_RGBA); + + if (span->array->ChanType == GL_UNSIGNED_BYTE) { + rFog = ctx->Fog.Color[RCOMP] * 255.0; + gFog = ctx->Fog.Color[GCOMP] * 255.0; + bFog = ctx->Fog.Color[BCOMP] * 255.0; + } + else if (span->array->ChanType == GL_UNSIGNED_SHORT) { + rFog = ctx->Fog.Color[RCOMP] * 65535.0; + gFog = ctx->Fog.Color[GCOMP] * 65535.0; + bFog = ctx->Fog.Color[BCOMP] * 65535.0; + } + else { + rFog = ctx->Fog.Color[RCOMP]; + gFog = ctx->Fog.Color[GCOMP]; + bFog = ctx->Fog.Color[BCOMP]; + } + + + /* NOTE: if haveW is true, that means the fog start/step values are + * perspective-corrected and we have to divide each fog coord by W. + */ + + /* we need to compute fog blend factors */ + if (swrast->_PreferPixelFog) { + /* The span's fog values are fog coordinates, now compute blend factors + * and blend the fragment colors with the fog color. + */ + 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); + const GLfloat density = -ctx->Fog.Density; + const GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density; + + switch (swrast->_FogMode) { + case GL_LINEAR: +#define COMPUTE_F f = (fogEnd - FABSF(fogCoord) / w) * fogScale; + if (span->array->ChanType == GL_UNSIGNED_BYTE) { + GLubyte (*rgba)[4] = span->array->color.sz1.rgba; + FOG_LOOP(GLubyte, COMPUTE_F); + } + else if (span->array->ChanType == GL_UNSIGNED_SHORT) { + GLushort (*rgba)[4] = span->array->color.sz2.rgba; + FOG_LOOP(GLushort, COMPUTE_F); + } + else { + GLfloat (*rgba)[4] = span->array->color.sz4.rgba; + ASSERT(span->array->ChanType == GL_FLOAT); + FOG_LOOP(GLfloat, COMPUTE_F); + } +#undef COMPUTE_F + break; + + case GL_EXP: +#define COMPUTE_F f = EXPF(density * FABSF(fogCoord) / w); + if (span->array->ChanType == GL_UNSIGNED_BYTE) { + GLubyte (*rgba)[4] = span->array->color.sz1.rgba; + FOG_LOOP(GLubyte, COMPUTE_F); + } + else if (span->array->ChanType == GL_UNSIGNED_SHORT) { + GLushort (*rgba)[4] = span->array->color.sz2.rgba; + FOG_LOOP(GLushort, COMPUTE_F); + } + else { + GLfloat (*rgba)[4] = span->array->color.sz4.rgba; + ASSERT(span->array->ChanType == GL_FLOAT); + FOG_LOOP(GLfloat, COMPUTE_F); + } +#undef COMPUTE_F + break; + + case GL_EXP2: +#define COMPUTE_F const GLfloat coord = fogCoord / w; \ + GLfloat tmp = negDensitySquared * coord * coord; \ + if (tmp < FLT_MIN_10_EXP) \ + tmp = FLT_MIN_10_EXP; \ + f = EXPF(tmp); + if (span->array->ChanType == GL_UNSIGNED_BYTE) { + GLubyte (*rgba)[4] = span->array->color.sz1.rgba; + FOG_LOOP(GLubyte, COMPUTE_F); + } + else if (span->array->ChanType == GL_UNSIGNED_SHORT) { + GLushort (*rgba)[4] = span->array->color.sz2.rgba; + FOG_LOOP(GLushort, COMPUTE_F); + } + else { + GLfloat (*rgba)[4] = span->array->color.sz4.rgba; + ASSERT(span->array->ChanType == GL_FLOAT); + FOG_LOOP(GLfloat, COMPUTE_F); + } +#undef COMPUTE_F + break; + + default: + _mesa_problem(ctx, "Bad fog mode in _swrast_fog_rgba_span"); + return; + } + } + else if (span->arrayMask & SPAN_FOG) { + /* The span's fog array values are blend factors. + * They were previously computed per-vertex. + */ + GLuint i; + if (span->array->ChanType == GL_UNSIGNED_BYTE) { + GLubyte (*rgba)[4] = span->array->color.sz1.rgba; + for (i = 0; i < span->end; i++) { + const GLfloat f = span->array->fog[i]; + const GLfloat oneMinusF = 1.0F - f; + rgba[i][RCOMP] = (GLubyte) (f * rgba[i][RCOMP] + oneMinusF * rFog); + rgba[i][GCOMP] = (GLubyte) (f * rgba[i][GCOMP] + oneMinusF * gFog); + rgba[i][BCOMP] = (GLubyte) (f * rgba[i][BCOMP] + oneMinusF * bFog); + } + } + else if (span->array->ChanType == GL_UNSIGNED_SHORT) { + GLushort (*rgba)[4] = span->array->color.sz2.rgba; + for (i = 0; i < span->end; i++) { + const GLfloat f = span->array->fog[i]; + const GLfloat oneMinusF = 1.0F - f; + rgba[i][RCOMP] = (GLushort) (f * rgba[i][RCOMP] + oneMinusF * rFog); + rgba[i][GCOMP] = (GLushort) (f * rgba[i][GCOMP] + oneMinusF * gFog); + rgba[i][BCOMP] = (GLushort) (f * rgba[i][BCOMP] + oneMinusF * bFog); + } + } + else { + GLfloat (*rgba)[4] = span->array->color.sz4.rgba; + ASSERT(span->array->ChanType == GL_FLOAT); + for (i = 0; i < span->end; i++) { + const GLfloat f = span->array->fog[i]; + const GLfloat oneMinusF = 1.0F - f; + rgba[i][RCOMP] = f * rgba[i][RCOMP] + oneMinusF * rFog; + rgba[i][GCOMP] = f * rgba[i][GCOMP] + oneMinusF * gFog; + rgba[i][BCOMP] = f * rgba[i][BCOMP] + oneMinusF * bFog; + } + } + + } + else { + /* The span's fog start/step values are blend factors. + * They were previously computed per-vertex. + */ +#define COMPUTE_F f = fogCoord / w; + if (span->array->ChanType == GL_UNSIGNED_BYTE) { + GLubyte (*rgba)[4] = span->array->color.sz1.rgba; + FOG_LOOP(GLubyte, COMPUTE_F); + } + else if (span->array->ChanType == GL_UNSIGNED_SHORT) { + GLushort (*rgba)[4] = span->array->color.sz2.rgba; + FOG_LOOP(GLushort, COMPUTE_F); + } + else { + GLfloat (*rgba)[4] = span->array->color.sz4.rgba; + ASSERT(span->array->ChanType == GL_FLOAT); + FOG_LOOP(GLfloat, COMPUTE_F); + } +#undef COMPUTE_F + } +} + + +/** + * As above, but color index mode. + */ +void +_swrast_fog_ci_span( const GLcontext *ctx, SWspan *span ) +{ + const SWcontext *swrast = SWRAST_CONTEXT(ctx); + const GLuint haveW = (span->interpMask & SPAN_W); + const GLuint fogIndex = (GLuint) ctx->Fog.Index; + GLuint *index = span->array->index; + + ASSERT(swrast->_FogEnabled); + ASSERT(span->arrayMask & SPAN_INDEX); + ASSERT((span->interpMask | span->arrayMask) & SPAN_FOG); + + /* we need to compute fog blend factors */ + 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); + const GLfloat fogStep = span->fogStep; + GLfloat fogCoord = span->fog; + const GLfloat wStep = haveW ? span->dwdx : 0.0F; + GLfloat w = haveW ? span->w : 1.0F; + GLuint i; + for (i = 0; i < span->end; i++) { + GLfloat f = (fogEnd - fogCoord / w) * fogScale; + f = CLAMP(f, 0.0F, 1.0F); + index[i] = (GLuint) ((GLfloat) index[i] + (1.0F - f) * fogIndex); + fogCoord += fogStep; + w += wStep; + } + } + break; + case GL_EXP: + { + const GLfloat density = -ctx->Fog.Density; + const GLfloat fogStep = span->fogStep; + GLfloat fogCoord = span->fog; + const GLfloat wStep = haveW ? span->dwdx : 0.0F; + GLfloat w = haveW ? span->w : 1.0F; + GLuint i; + for (i = 0; i < span->end; i++) { + GLfloat f = EXPF(density * fogCoord / w); + f = CLAMP(f, 0.0F, 1.0F); + index[i] = (GLuint) ((GLfloat) index[i] + (1.0F - f) * fogIndex); + fogCoord += fogStep; + w += wStep; + } + } + break; + case GL_EXP2: + { + const GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density; + const GLfloat fogStep = span->fogStep; + GLfloat fogCoord = span->fog; + const GLfloat wStep = haveW ? span->dwdx : 0.0F; + GLfloat w = haveW ? span->w : 1.0F; + GLuint i; + for (i = 0; i < span->end; i++) { + const GLfloat coord = fogCoord / w; + GLfloat tmp = negDensitySquared * coord * coord; + GLfloat f; +#if defined(__alpha__) || defined(__alpha) + /* XXX this underflow check may be needed for other systems*/ + if (tmp < FLT_MIN_10_EXP) + tmp = FLT_MIN_10_EXP; +#endif + f = EXPF(tmp); + f = CLAMP(f, 0.0F, 1.0F); + index[i] = (GLuint) ((GLfloat) index[i] + (1.0F - f) * fogIndex); + fogCoord += fogStep; + w += wStep; + } + } + break; + default: + _mesa_problem(ctx, "Bad fog mode in _swrast_fog_ci_span"); + return; + } + } + else if (span->arrayMask & SPAN_FOG) { + /* The span's fog array values are blend factors. + * They were previously computed per-vertex. + */ + GLuint i; + for (i = 0; i < span->end; i++) { + const GLfloat f = span->array->fog[i]; + index[i] = (GLuint) ((GLfloat) index[i] + (1.0F - f) * fogIndex); + } + } + else { + /* The span's fog start/step values are blend factors. + * They were previously computed per-vertex. + */ + const GLfloat fogStep = span->fogStep; + GLfloat fog = span->fog; + const GLfloat wStep = haveW ? span->dwdx : 0.0F; + GLfloat w = haveW ? span->w : 1.0F; + GLuint i; + ASSERT(span->interpMask & SPAN_FOG); + for (i = 0; i < span->end; i++) { + const GLfloat f = fog / w; + index[i] = (GLuint) ((GLfloat) index[i] + (1.0F - f) * fogIndex); + fog += fogStep; + w += wStep; + } + } +} |