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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4358 | Serge | 1 | /* |
| 2 | * Mesa 3-D graphics library |
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| 3 | * |
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| 4 | * Copyright (C) 1999-2006 Brian Paul All Rights Reserved. |
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| 5 | * |
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| 6 | * Permission is hereby granted, free of charge, to any person obtaining a |
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| 7 | * copy of this software and associated documentation files (the "Software"), |
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| 8 | * to deal in the Software without restriction, including without limitation |
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| 9 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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| 10 | * and/or sell copies of the Software, and to permit persons to whom the |
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| 11 | * Software is furnished to do so, subject to the following conditions: |
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| 12 | * |
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| 13 | * The above copyright notice and this permission notice shall be included |
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| 14 | * in all copies or substantial portions of the Software. |
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| 15 | * |
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| 16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
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| 17 | * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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| 18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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| 19 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR |
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| 20 | * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, |
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| 21 | * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR |
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| 22 | * OTHER DEALINGS IN THE SOFTWARE. |
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| 23 | */ |
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| 24 | |||
| 25 | |||
| 26 | #include "main/glheader.h" |
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| 27 | #include "main/colormac.h" |
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| 28 | #include "main/macros.h" |
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| 29 | |||
| 30 | #include "s_context.h" |
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| 31 | #include "s_fog.h" |
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| 32 | |||
| 33 | |||
| 34 | /** |
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| 35 | * Used to convert current raster distance to a fog factor in [0,1]. |
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| 36 | */ |
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| 37 | GLfloat |
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| 38 | _swrast_z_to_fogfactor(struct gl_context *ctx, GLfloat z) |
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| 39 | { |
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| 40 | GLfloat d, f; |
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| 41 | |||
| 42 | switch (ctx->Fog.Mode) { |
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| 43 | case GL_LINEAR: |
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| 44 | if (ctx->Fog.Start == ctx->Fog.End) |
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| 45 | d = 1.0F; |
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| 46 | else |
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| 47 | d = 1.0F / (ctx->Fog.End - ctx->Fog.Start); |
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| 48 | f = (ctx->Fog.End - z) * d; |
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| 49 | return CLAMP(f, 0.0F, 1.0F); |
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| 50 | case GL_EXP: |
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| 51 | d = ctx->Fog.Density; |
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| 52 | f = EXPF(-d * z); |
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| 53 | f = CLAMP(f, 0.0F, 1.0F); |
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| 54 | return f; |
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| 55 | case GL_EXP2: |
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| 56 | d = ctx->Fog.Density; |
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| 57 | f = EXPF(-(d * d * z * z)); |
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| 58 | f = CLAMP(f, 0.0F, 1.0F); |
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| 59 | return f; |
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| 60 | default: |
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| 61 | _mesa_problem(ctx, "Bad fog mode in _swrast_z_to_fogfactor"); |
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| 62 | return 0.0; |
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| 63 | } |
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| 64 | } |
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| 65 | |||
| 66 | |||
| 67 | #define LINEAR_FOG(f, coord) f = (fogEnd - coord) * fogScale |
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| 68 | |||
| 69 | #define EXP_FOG(f, coord) f = EXPF(density * coord) |
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| 70 | |||
| 71 | #define EXP2_FOG(f, coord) \ |
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| 72 | do { \ |
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| 73 | GLfloat tmp = negDensitySquared * coord * coord; \ |
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| 74 | if (tmp < FLT_MIN_10_EXP) \ |
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| 75 | tmp = FLT_MIN_10_EXP; \ |
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| 76 | f = EXPF(tmp); \ |
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| 77 | } while(0) |
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| 78 | |||
| 79 | |||
| 80 | #define BLEND_FOG(f, coord) f = coord |
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| 81 | |||
| 82 | |||
| 83 | |||
| 84 | /** |
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| 85 | * Template code for computing fog blend factor and applying it to colors. |
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| 86 | * \param TYPE either GLubyte, GLushort or GLfloat. |
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| 87 | * \param COMPUTE_F code to compute the fog blend factor, f. |
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| 88 | */ |
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| 89 | #define FOG_LOOP(TYPE, FOG_FUNC) \ |
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| 90 | if (span->arrayAttribs & VARYING_BIT_FOGC) { \ |
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| 91 | GLuint i; \ |
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| 92 | for (i = 0; i < span->end; i++) { \ |
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| 93 | const GLfloat fogCoord = span->array->attribs[VARYING_SLOT_FOGC][i][0]; \ |
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| 94 | const GLfloat c = FABSF(fogCoord); \ |
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| 95 | GLfloat f, oneMinusF; \ |
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| 96 | FOG_FUNC(f, c); \ |
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| 97 | f = CLAMP(f, 0.0F, 1.0F); \ |
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| 98 | oneMinusF = 1.0F - f; \ |
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| 99 | rgba[i][RCOMP] = (TYPE) (f * rgba[i][RCOMP] + oneMinusF * rFog); \ |
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| 100 | rgba[i][GCOMP] = (TYPE) (f * rgba[i][GCOMP] + oneMinusF * gFog); \ |
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| 101 | rgba[i][BCOMP] = (TYPE) (f * rgba[i][BCOMP] + oneMinusF * bFog); \ |
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| 102 | } \ |
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| 103 | } \ |
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| 104 | else { \ |
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| 105 | const GLfloat fogStep = span->attrStepX[VARYING_SLOT_FOGC][0]; \ |
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| 106 | GLfloat fogCoord = span->attrStart[VARYING_SLOT_FOGC][0]; \ |
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| 107 | const GLfloat wStep = span->attrStepX[VARYING_SLOT_POS][3]; \ |
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| 108 | GLfloat w = span->attrStart[VARYING_SLOT_POS][3]; \ |
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| 109 | GLuint i; \ |
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| 110 | for (i = 0; i < span->end; i++) { \ |
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| 111 | const GLfloat c = FABSF(fogCoord) / w; \ |
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| 112 | GLfloat f, oneMinusF; \ |
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| 113 | FOG_FUNC(f, c); \ |
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| 114 | f = CLAMP(f, 0.0F, 1.0F); \ |
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| 115 | oneMinusF = 1.0F - f; \ |
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| 116 | rgba[i][RCOMP] = (TYPE) (f * rgba[i][RCOMP] + oneMinusF * rFog); \ |
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| 117 | rgba[i][GCOMP] = (TYPE) (f * rgba[i][GCOMP] + oneMinusF * gFog); \ |
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| 118 | rgba[i][BCOMP] = (TYPE) (f * rgba[i][BCOMP] + oneMinusF * bFog); \ |
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| 119 | fogCoord += fogStep; \ |
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| 120 | w += wStep; \ |
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| 121 | } \ |
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| 122 | } |
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| 123 | |||
| 124 | /** |
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| 125 | * Apply fog to a span of RGBA pixels. |
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| 126 | * The fog value are either in the span->array->fog array or interpolated from |
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| 127 | * the fog/fogStep values. |
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| 128 | * They fog values are either fog coordinates (Z) or fog blend factors. |
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| 129 | * _PreferPixelFog should be in sync with that state! |
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| 130 | */ |
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| 131 | void |
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| 132 | _swrast_fog_rgba_span( const struct gl_context *ctx, SWspan *span ) |
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| 133 | { |
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| 134 | const SWcontext *swrast = CONST_SWRAST_CONTEXT(ctx); |
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| 135 | GLfloat rFog, gFog, bFog; |
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| 136 | |||
| 137 | ASSERT(swrast->_FogEnabled); |
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| 138 | ASSERT(span->arrayMask & SPAN_RGBA); |
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| 139 | |||
| 140 | /* compute (scaled) fog color */ |
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| 141 | if (span->array->ChanType == GL_UNSIGNED_BYTE) { |
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| 142 | rFog = ctx->Fog.Color[RCOMP] * 255.0F; |
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| 143 | gFog = ctx->Fog.Color[GCOMP] * 255.0F; |
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| 144 | bFog = ctx->Fog.Color[BCOMP] * 255.0F; |
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| 145 | } |
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| 146 | else if (span->array->ChanType == GL_UNSIGNED_SHORT) { |
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| 147 | rFog = ctx->Fog.Color[RCOMP] * 65535.0F; |
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| 148 | gFog = ctx->Fog.Color[GCOMP] * 65535.0F; |
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| 149 | bFog = ctx->Fog.Color[BCOMP] * 65535.0F; |
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| 150 | } |
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| 151 | else { |
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| 152 | rFog = ctx->Fog.Color[RCOMP]; |
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| 153 | gFog = ctx->Fog.Color[GCOMP]; |
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| 154 | bFog = ctx->Fog.Color[BCOMP]; |
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| 155 | } |
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| 156 | |||
| 157 | if (swrast->_PreferPixelFog) { |
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| 158 | /* The span's fog values are fog coordinates, now compute blend factors |
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| 159 | * and blend the fragment colors with the fog color. |
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| 160 | */ |
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| 161 | switch (ctx->Fog.Mode) { |
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| 162 | case GL_LINEAR: |
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| 163 | { |
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| 164 | const GLfloat fogEnd = ctx->Fog.End; |
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| 165 | const GLfloat fogScale = (ctx->Fog.Start == ctx->Fog.End) |
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| 166 | ? 1.0F : 1.0F / (ctx->Fog.End - ctx->Fog.Start); |
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| 167 | if (span->array->ChanType == GL_UNSIGNED_BYTE) { |
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| 168 | GLubyte (*rgba)[4] = span->array->rgba8; |
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| 169 | FOG_LOOP(GLubyte, LINEAR_FOG); |
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| 170 | } |
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| 171 | else if (span->array->ChanType == GL_UNSIGNED_SHORT) { |
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| 172 | GLushort (*rgba)[4] = span->array->rgba16; |
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| 173 | FOG_LOOP(GLushort, LINEAR_FOG); |
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| 174 | } |
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| 175 | else { |
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| 176 | GLfloat (*rgba)[4] = span->array->attribs[VARYING_SLOT_COL0]; |
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| 177 | ASSERT(span->array->ChanType == GL_FLOAT); |
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| 178 | FOG_LOOP(GLfloat, LINEAR_FOG); |
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| 179 | } |
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| 180 | } |
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| 181 | break; |
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| 182 | |||
| 183 | case GL_EXP: |
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| 184 | { |
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| 185 | const GLfloat density = -ctx->Fog.Density; |
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| 186 | if (span->array->ChanType == GL_UNSIGNED_BYTE) { |
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| 187 | GLubyte (*rgba)[4] = span->array->rgba8; |
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| 188 | FOG_LOOP(GLubyte, EXP_FOG); |
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| 189 | } |
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| 190 | else if (span->array->ChanType == GL_UNSIGNED_SHORT) { |
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| 191 | GLushort (*rgba)[4] = span->array->rgba16; |
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| 192 | FOG_LOOP(GLushort, EXP_FOG); |
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| 193 | } |
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| 194 | else { |
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| 195 | GLfloat (*rgba)[4] = span->array->attribs[VARYING_SLOT_COL0]; |
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| 196 | ASSERT(span->array->ChanType == GL_FLOAT); |
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| 197 | FOG_LOOP(GLfloat, EXP_FOG); |
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| 198 | } |
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| 199 | } |
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| 200 | break; |
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| 201 | |||
| 202 | case GL_EXP2: |
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| 203 | { |
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| 204 | const GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density; |
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| 205 | if (span->array->ChanType == GL_UNSIGNED_BYTE) { |
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| 206 | GLubyte (*rgba)[4] = span->array->rgba8; |
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| 207 | FOG_LOOP(GLubyte, EXP2_FOG); |
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| 208 | } |
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| 209 | else if (span->array->ChanType == GL_UNSIGNED_SHORT) { |
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| 210 | GLushort (*rgba)[4] = span->array->rgba16; |
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| 211 | FOG_LOOP(GLushort, EXP2_FOG); |
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| 212 | } |
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| 213 | else { |
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| 214 | GLfloat (*rgba)[4] = span->array->attribs[VARYING_SLOT_COL0]; |
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| 215 | ASSERT(span->array->ChanType == GL_FLOAT); |
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| 216 | FOG_LOOP(GLfloat, EXP2_FOG); |
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| 217 | } |
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| 218 | } |
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| 219 | break; |
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| 220 | |||
| 221 | default: |
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| 222 | _mesa_problem(ctx, "Bad fog mode in _swrast_fog_rgba_span"); |
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| 223 | return; |
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| 224 | } |
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| 225 | } |
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| 226 | else { |
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| 227 | /* The span's fog start/step/array values are blend factors in [0,1]. |
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| 228 | * They were previously computed per-vertex. |
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| 229 | */ |
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| 230 | if (span->array->ChanType == GL_UNSIGNED_BYTE) { |
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| 231 | GLubyte (*rgba)[4] = span->array->rgba8; |
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| 232 | FOG_LOOP(GLubyte, BLEND_FOG); |
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| 233 | } |
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| 234 | else if (span->array->ChanType == GL_UNSIGNED_SHORT) { |
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| 235 | GLushort (*rgba)[4] = span->array->rgba16; |
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| 236 | FOG_LOOP(GLushort, BLEND_FOG); |
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| 237 | } |
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| 238 | else { |
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| 239 | GLfloat (*rgba)[4] = span->array->attribs[VARYING_SLOT_COL0]; |
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| 240 | ASSERT(span->array->ChanType == GL_FLOAT); |
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| 241 | FOG_LOOP(GLfloat, BLEND_FOG); |
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| 242 | } |
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| 243 | } |
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| 244 | } |