| /* |
| * 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 "c99_math.h" |
| #include "main/glheader.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); |
| } |
| } |
| } |
