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1901 | serge | 1 | /* |
2 | * Mesa 3-D graphics library |
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3 | * Version: 6.5.2 |
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4 | * |
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5 | * Copyright (C) 1999-2006 Brian Paul All Rights Reserved. |
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6 | * |
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7 | * Permission is hereby granted, free of charge, to any person obtaining a |
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8 | * copy of this software and associated documentation files (the "Software"), |
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9 | * to deal in the Software without restriction, including without limitation |
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10 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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11 | * and/or sell copies of the Software, and to permit persons to whom the |
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12 | * Software is furnished to do so, subject to the following conditions: |
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13 | * |
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14 | * The above copyright notice and this permission notice shall be included |
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15 | * in all copies or substantial portions of the Software. |
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16 | * |
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17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
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18 | * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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19 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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20 | * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN |
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21 | * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
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22 | * CONNECTION WITH THE SOFTWARE OR THE USE OR 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 & FRAG_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[FRAG_ATTRIB_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[FRAG_ATTRIB_FOGC][0]; \ |
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106 | GLfloat fogCoord = span->attrStart[FRAG_ATTRIB_FOGC][0]; \ |
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107 | const GLfloat wStep = span->attrStepX[FRAG_ATTRIB_WPOS][3]; \ |
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108 | GLfloat w = span->attrStart[FRAG_ATTRIB_WPOS][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 (swrast->_FogMode) { |
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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[FRAG_ATTRIB_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[FRAG_ATTRIB_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[FRAG_ATTRIB_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[FRAG_ATTRIB_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 | }>>> |