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Diffstat (limited to 'src/mesa/swrast/s_fog.c')
| -rw-r--r-- | src/mesa/swrast/s_fog.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/src/mesa/swrast/s_fog.c b/src/mesa/swrast/s_fog.c new file mode 100644 index 00000000000..32fafe617c8 --- /dev/null +++ b/src/mesa/swrast/s_fog.c @@ -0,0 +1,188 @@ +/* $Id: s_fog.c,v 1.1 2000/10/31 18:00:04 keithw Exp $ */ + +/* + * Mesa 3-D graphics library + * Version: 3.5 + * + * 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"), + * 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 "mmath.h" + +#include "s_fog.h" + + +/* + * Apply fog to an array of RGBA pixels. + * Input: n - number of pixels + * fog - array of interpolated screen-space fog coordinates in [0..1] + * red, green, blue, alpha - pixel colors + * Output: red, green, blue, alpha - fogged pixel colors + */ +void +_mesa_fog_rgba_pixels( const GLcontext *ctx, + GLuint n, + const GLfixed fog[], + GLchan rgba[][4] ) +{ + GLfixed rFog = ctx->Fog.Color[0] * CHAN_MAXF; + GLfixed gFog = ctx->Fog.Color[1] * CHAN_MAXF; + GLfixed bFog = ctx->Fog.Color[2] * CHAN_MAXF; + GLuint i; + + for (i=0;i<n;i++) { + GLfixed f = CLAMP(fog[i], 0, FIXED_ONE); + GLfixed g = FIXED_ONE - f; + rgba[i][0] = (f*rgba[i][0] + g*rFog) >> FIXED_SHIFT; + rgba[i][1] = (f*rgba[i][1] + g*gFog) >> FIXED_SHIFT; + rgba[i][2] = (f*rgba[i][2] + g*bFog) >> FIXED_SHIFT; + } +} + + + + +/* + * Apply fog to an array of color index pixels. + * Input: n - number of pixels + * z - array of integer depth values + * index - pixel color indexes + * Output: index - fogged pixel color indexes + */ +void +_mesa_fog_ci_pixels( const GLcontext *ctx, + GLuint n, const GLfixed fog[], GLuint index[] ) +{ + GLuint idx = ctx->Fog.Index; + GLuint i; + + for (i=0;i<n;i++) { + GLfixed f = FixedToFloat(CLAMP(fog[i], 0, FIXED_ONE)); + index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * idx); + } +} + + + +/* + * Calculate fog coords from window z values + * Input: n - number of pixels + * z - array of integer depth values + * red, green, blue, alpha - pixel colors + * Output: red, green, blue, alpha - fogged pixel colors + * + * Use lookup table & interpolation? + */ +void +_mesa_win_fog_coords_from_z( const GLcontext *ctx, + GLuint n, + const GLdepth z[], + GLfixed fogcoord[] ) +{ + GLfloat c = ctx->ProjectionMatrix.m[10]; + GLfloat d = ctx->ProjectionMatrix.m[14]; + GLuint i; + + GLfloat tz = ctx->Viewport.WindowMap.m[MAT_TZ]; + GLfloat szInv = 1.0F / ctx->Viewport.WindowMap.m[MAT_SZ]; + + switch (ctx->Fog.Mode) { + case GL_LINEAR: + { + GLfloat fogEnd = ctx->Fog.End; + GLfloat fogScale = (GLfloat) FIXED_ONE / (ctx->Fog.End - + ctx->Fog.Start); + for (i=0;i<n;i++) { + GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv; + GLfloat eyez = -d / (c+ndcz); + if (eyez < 0.0) eyez = -eyez; + fogcoord[i] = (GLint)(fogEnd - eyez) * fogScale; + } + } + break; + case GL_EXP: + for (i=0;i<n;i++) { + GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv; + GLfloat eyez = d / (c+ndcz); + if (eyez < 0.0) eyez = -eyez; + fogcoord[i] = FloatToFixed(exp( -ctx->Fog.Density * eyez )); + } + break; + case GL_EXP2: + { + GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density; + for (i=0;i<n;i++) { + GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv; + GLfloat eyez = d / (c+ndcz); + GLfloat tmp = negDensitySquared * eyez * eyez; +#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 + fogcoord[i] = FloatToFixed(exp( tmp )); + } + } + break; + default: + gl_problem(ctx, "Bad fog mode in _mesa_win_fog_coords_from_z"); + return; + } +} + + +/* + * Apply fog to an array of RGBA pixels. + * Input: n - number of pixels + * z - array of integer depth values + * red, green, blue, alpha - pixel colors + * Output: red, green, blue, alpha - fogged pixel colors + */ +void +_mesa_depth_fog_rgba_pixels( const GLcontext *ctx, + GLuint n, const GLdepth z[], GLchan rgba[][4] ) +{ + GLfixed fog[MAX_WIDTH]; + _mesa_win_fog_coords_from_z( ctx, n, z, fog ); + _mesa_fog_rgba_pixels( ctx, n, fog, rgba ); +} + + +/* + * Apply fog to an array of color index pixels. + * Input: n - number of pixels + * z - array of integer depth values + * index - pixel color indexes + * Output: index - fogged pixel color indexes + */ +void +_mesa_depth_fog_ci_pixels( const GLcontext *ctx, + GLuint n, const GLdepth z[], GLuint index[] ) +{ + GLfixed fog[MAX_WIDTH]; + _mesa_win_fog_coords_from_z( ctx, n, z, fog ); + _mesa_fog_ci_pixels( ctx, n, fog, index ); +} + |