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56 | pj | 1 | /* $Id: t_vb_fog.c,v 1.1 2003-02-28 11:48:07 pj Exp $ */ |
2 | |||
3 | /* |
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4 | * Mesa 3-D graphics library |
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5 | * Version: 4.1 |
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6 | * |
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7 | * Copyright (C) 1999-2002 Brian Paul All Rights Reserved. |
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8 | * |
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9 | * Permission is hereby granted, free of charge, to any person obtaining a |
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10 | * copy of this software and associated documentation files (the "Software"), |
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11 | * to deal in the Software without restriction, including without limitation |
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12 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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13 | * and/or sell copies of the Software, and to permit persons to whom the |
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14 | * Software is furnished to do so, subject to the following conditions: |
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15 | * |
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16 | * The above copyright notice and this permission notice shall be included |
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17 | * in all copies or substantial portions of the Software. |
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18 | * |
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19 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS |
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20 | * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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21 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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22 | * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN |
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23 | * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
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24 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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25 | * |
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26 | * Authors: |
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27 | * Keith Whitwell <keith@tungstengraphics.com> |
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28 | */ |
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29 | |||
30 | |||
31 | #include "glheader.h" |
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32 | #include "colormac.h" |
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33 | #include "context.h" |
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34 | #include "macros.h" |
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35 | #include "imports.h" |
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36 | #include "mmath.h" |
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37 | #include "mtypes.h" |
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38 | |||
39 | #include "math/m_xform.h" |
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40 | |||
41 | #include "t_context.h" |
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42 | #include "t_pipeline.h" |
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43 | |||
44 | |||
45 | struct fog_stage_data { |
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46 | GLvector4f fogcoord; /* has actual storage allocated */ |
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47 | GLvector4f input; /* points into VB->EyePtr Z values */ |
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48 | }; |
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49 | |||
50 | #define FOG_STAGE_DATA(stage) ((struct fog_stage_data *)stage->privatePtr) |
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51 | |||
52 | #define FOG_EXP_TABLE_SIZE 256 |
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53 | #define FOG_MAX (10.0) |
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54 | #define EXP_FOG_MAX .0006595 |
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55 | #define FOG_INCR (FOG_MAX/FOG_EXP_TABLE_SIZE) |
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56 | static GLfloat exp_table[FOG_EXP_TABLE_SIZE]; |
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57 | static GLfloat inited = 0; |
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58 | |||
59 | #if 1 |
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60 | #define NEG_EXP( result, narg ) \ |
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61 | do { \ |
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62 | GLfloat f = (GLfloat) (narg * (1.0/FOG_INCR)); \ |
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63 | GLint k = (GLint) f; \ |
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64 | if (k > FOG_EXP_TABLE_SIZE-2) \ |
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65 | result = (GLfloat) EXP_FOG_MAX; \ |
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66 | else \ |
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67 | result = exp_table[k] + (f-k)*(exp_table[k+1]-exp_table[k]); \ |
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68 | } while (0) |
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69 | #else |
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70 | #define NEG_EXP( result, narg ) \ |
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71 | do { \ |
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72 | result = exp(-narg); \ |
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73 | } while (0) |
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74 | #endif |
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75 | |||
76 | |||
77 | static void init_static_data( void ) |
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78 | { |
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79 | GLfloat f = 0.0F; |
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80 | GLint i = 0; |
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81 | for ( ; i < FOG_EXP_TABLE_SIZE ; i++, f += FOG_INCR) { |
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82 | exp_table[i] = (GLfloat) exp(-f); |
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83 | } |
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84 | inited = 1; |
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85 | } |
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86 | |||
87 | |||
88 | static void make_win_fog_coords( GLcontext *ctx, GLvector4f *out, |
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89 | const GLvector4f *in ) |
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90 | { |
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91 | GLfloat end = ctx->Fog.End; |
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92 | GLfloat *v = in->start; |
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93 | GLuint stride = in->stride; |
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94 | GLuint n = in->count; |
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95 | GLfloat (*data)[4] = out->data; |
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96 | GLfloat d; |
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97 | GLuint i; |
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98 | |||
99 | out->count = in->count; |
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100 | |||
101 | switch (ctx->Fog.Mode) { |
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102 | case GL_LINEAR: |
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103 | if (ctx->Fog.Start == ctx->Fog.End) |
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104 | d = 1.0F; |
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105 | else |
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106 | d = 1.0F / (ctx->Fog.End - ctx->Fog.Start); |
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107 | for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) { |
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108 | GLfloat f = (end - ABSF(*v)) * d; |
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109 | data[i][0] = CLAMP(f, 0.0F, 1.0F); |
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110 | } |
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111 | break; |
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112 | case GL_EXP: |
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113 | d = ctx->Fog.Density; |
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114 | for ( i = 0 ; i < n ; i++, STRIDE_F(v,stride)) |
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115 | NEG_EXP( data[i][0], d * ABSF(*v) ); |
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116 | break; |
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117 | case GL_EXP2: |
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118 | d = ctx->Fog.Density*ctx->Fog.Density; |
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119 | for ( i = 0 ; i < n ; i++, STRIDE_F(v, stride)) { |
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120 | GLfloat z = *v; |
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121 | NEG_EXP( data[i][0], d * z * z ); |
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122 | } |
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123 | break; |
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124 | default: |
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125 | _mesa_problem(ctx, "Bad fog mode in make_fog_coord"); |
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126 | return; |
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127 | } |
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128 | } |
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129 | |||
130 | |||
131 | static GLboolean run_fog_stage( GLcontext *ctx, |
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132 | struct gl_pipeline_stage *stage ) |
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133 | { |
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134 | struct vertex_buffer *VB = &TNL_CONTEXT(ctx)->vb; |
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135 | struct fog_stage_data *store = FOG_STAGE_DATA(stage); |
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136 | GLvector4f *input; |
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137 | |||
138 | if (stage->changed_inputs == 0) |
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139 | return GL_TRUE; |
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140 | |||
141 | if (ctx->Fog.FogCoordinateSource == GL_FRAGMENT_DEPTH_EXT) { |
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142 | /* fog computed from Z depth */ |
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143 | /* source = VB->ObjPtr or VB->EyePtr coords */ |
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144 | /* dest = VB->FogCoordPtr = fog stage private storage */ |
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145 | VB->FogCoordPtr = &store->fogcoord; |
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146 | |||
147 | if (!ctx->_NeedEyeCoords) { |
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148 | const GLfloat *m = ctx->ModelviewMatrixStack.Top->m; |
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149 | GLfloat plane[4]; |
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150 | |||
151 | /* Use this to store calculated eye z values: |
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152 | */ |
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153 | input = &store->fogcoord; |
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154 | |||
155 | plane[0] = m[2]; |
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156 | plane[1] = m[6]; |
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157 | plane[2] = m[10]; |
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158 | plane[3] = m[14]; |
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159 | |||
160 | /* Full eye coords weren't required, just calculate the |
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161 | * eye Z values. |
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162 | */ |
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163 | _mesa_dotprod_tab[VB->ObjPtr->size]( (GLfloat *) input->data, |
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164 | 4 * sizeof(GLfloat), |
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165 | VB->ObjPtr, plane ); |
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166 | |||
167 | input->count = VB->ObjPtr->count; |
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168 | } |
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169 | else { |
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170 | input = &store->input; |
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171 | |||
172 | if (VB->EyePtr->size < 2) |
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173 | _mesa_vector4f_clean_elem( VB->EyePtr, VB->Count, 2 ); |
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174 | |||
175 | input->data = (GLfloat (*)[4]) &(VB->EyePtr->data[0][2]); |
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176 | input->start = VB->EyePtr->start+2; |
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177 | input->stride = VB->EyePtr->stride; |
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178 | input->count = VB->EyePtr->count; |
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179 | } |
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180 | } |
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181 | else { |
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182 | /* use glFogCoord() coordinates */ |
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183 | /* source = VB->FogCoordPtr */ |
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184 | input = VB->FogCoordPtr; |
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185 | /* dest = fog stage private storage */ |
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186 | VB->FogCoordPtr = &store->fogcoord; |
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187 | } |
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188 | |||
189 | make_win_fog_coords( ctx, VB->FogCoordPtr, input ); |
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190 | return GL_TRUE; |
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191 | } |
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192 | |||
193 | |||
194 | static void check_fog_stage( GLcontext *ctx, struct gl_pipeline_stage *stage ) |
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195 | { |
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196 | stage->active = ctx->Fog.Enabled && !ctx->VertexProgram.Enabled; |
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197 | |||
198 | if (ctx->Fog.FogCoordinateSource == GL_FRAGMENT_DEPTH_EXT) |
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199 | stage->inputs = VERT_BIT_EYE; |
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200 | else |
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201 | stage->inputs = VERT_BIT_FOG; |
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202 | } |
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203 | |||
204 | |||
205 | /* Called the first time stage->run() is invoked. |
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206 | */ |
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207 | static GLboolean alloc_fog_data( GLcontext *ctx, |
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208 | struct gl_pipeline_stage *stage ) |
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209 | { |
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210 | TNLcontext *tnl = TNL_CONTEXT(ctx); |
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211 | struct fog_stage_data *store; |
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212 | stage->privatePtr = MALLOC(sizeof(*store)); |
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213 | store = FOG_STAGE_DATA(stage); |
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214 | if (!store) |
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215 | return GL_FALSE; |
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216 | |||
217 | _mesa_vector4f_alloc( &store->fogcoord, 0, tnl->vb.Size, 32 ); |
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218 | _mesa_vector4f_init( &store->input, 0, 0 ); |
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219 | |||
220 | if (!inited) |
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221 | init_static_data(); |
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222 | |||
223 | /* Now run the stage. |
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224 | */ |
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225 | stage->run = run_fog_stage; |
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226 | return stage->run( ctx, stage ); |
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227 | } |
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228 | |||
229 | |||
230 | static void free_fog_data( struct gl_pipeline_stage *stage ) |
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231 | { |
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232 | struct fog_stage_data *store = FOG_STAGE_DATA(stage); |
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233 | if (store) { |
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234 | _mesa_vector4f_free( &store->fogcoord ); |
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235 | FREE( store ); |
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236 | stage->privatePtr = NULL; |
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237 | } |
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238 | } |
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239 | |||
240 | |||
241 | const struct gl_pipeline_stage _tnl_fog_coordinate_stage = |
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242 | { |
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243 | "build fog coordinates", /* name */ |
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244 | _NEW_FOG, /* check_state */ |
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245 | _NEW_FOG, /* run_state */ |
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246 | GL_FALSE, /* active? */ |
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247 | 0, /* inputs */ |
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248 | VERT_BIT_FOG, /* outputs */ |
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249 | 0, /* changed_inputs */ |
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250 | NULL, /* private_data */ |
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251 | free_fog_data, /* dtr */ |
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252 | check_fog_stage, /* check */ |
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253 | alloc_fog_data /* run -- initially set to init. */ |
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254 | }; |