src/mesa/main/fog.c

   1 /* $Id: fog.c,v 1.7 2000/02/25 03:55:40 keithw Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.3
   6  *
   7  * Copyright (C) 1999-2000  Brian Paul   All Rights Reserved.
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a
  10  * copy of this software and associated documentation files (the "Software"),
  11  * to deal in the Software without restriction, including without limitation
  12  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  13  * and/or sell copies of the Software, and to permit persons to whom the
  14  * Software is furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included
  17  * in all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  20  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  22  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  23  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  24  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  */
  26
  27
  28 #ifdef PC_HEADER
  29 #include "all.h"
  30 #else
  31 #include "glheader.h"
  32 #include "context.h"
  33 #include "fog.h"
  34 #include "macros.h"
  35 #include "mmath.h"
  36 #include "types.h"
  37 #include "xform.h"
  38 #endif
  39
  40
  41
  42 void
  43 _mesa_Fogf(GLenum pname, GLfloat param)
  44 {
  45    _mesa_Fogfv(pname, &param);
  46 }
  47
  48
  49 void
  50 _mesa_Fogi(GLenum pname, GLint param )
  51 {
  52    GLfloat fparam = (GLfloat) param;
  53    _mesa_Fogfv(pname, &fparam);
  54 }
  55
  56
  57 void
  58 _mesa_Fogiv(GLenum pname, const GLint *params )
  59 {
  60    GLfloat p[4];
  61    switch (pname) {
  62       case GL_FOG_MODE:
  63       case GL_FOG_DENSITY:
  64       case GL_FOG_START:
  65       case GL_FOG_END:
  66       case GL_FOG_INDEX:
  67          p[0] = (GLfloat) *params;
  68          break;
  69       case GL_FOG_COLOR:
  70          p[0] = INT_TO_FLOAT( params[0] );
  71          p[1] = INT_TO_FLOAT( params[1] );
  72          p[2] = INT_TO_FLOAT( params[2] );
  73          p[3] = INT_TO_FLOAT( params[3] );
  74          break;
  75       default:
  76          /* Error will be caught later in _mesa_Fogfv */
  77          ;
  78    }
  79    _mesa_Fogfv(pname, p);
  80 }
  81
  82
  83 void
  84 _mesa_Fogfv( GLenum pname, const GLfloat *params )
  85 {
  86    GET_CURRENT_CONTEXT(ctx);
  87    GLenum m;
  88
  89    switch (pname) {
  90       case GL_FOG_MODE:
  91          m = (GLenum) (GLint) *params;
  92          if (m==GL_LINEAR || m==GL_EXP || m==GL_EXP2) {
  93             ctx->Fog.Mode = m;
  94          }
  95          else {
  96             gl_error( ctx, GL_INVALID_ENUM, "glFog" );
  97             return;
  98          }
  99          break;
 100       case GL_FOG_DENSITY:
 101          if (*params<0.0) {
 102             gl_error( ctx, GL_INVALID_VALUE, "glFog" );
 103             return;
 104          }
 105          else {
 106             ctx->Fog.Density = *params;
 107          }
 108          break;
 109       case GL_FOG_START:
 110          ctx->Fog.Start = *params;
 111          break;
 112       case GL_FOG_END:
 113          ctx->Fog.End = *params;
 114          break;
 115       case GL_FOG_INDEX:
 116          ctx->Fog.Index = *params;
 117          break;
 118       case GL_FOG_COLOR:
 119          ctx->Fog.Color[0] = params[0];
 120          ctx->Fog.Color[1] = params[1];
 121          ctx->Fog.Color[2] = params[2];
 122          ctx->Fog.Color[3] = params[3];
 123          break;
 124       default:
 125          gl_error( ctx, GL_INVALID_ENUM, "glFog" );
 126          return;
 127    }
 128
 129    if (ctx->Driver.Fogfv) {
 130       (*ctx->Driver.Fogfv)( ctx, pname, params );
 131    }
 132
 133    ctx->NewState |= NEW_FOG;
 134 }
 135
 136
 137 typedef void (*fog_func)( struct vertex_buffer *VB, GLuint side,
 138                           GLubyte flag );
 139
 140 typedef void (*fog_coord_func)( struct vertex_buffer *VB,
 141                                 const GLvector4f *from,
 142                                 GLubyte flag );
 143
 144 static fog_func fog_ci_tab[2];
 145 static fog_func fog_rgba_tab[2];
 146 static fog_coord_func make_fog_coord_tab[2];
 147
 148 /*
 149  * Compute the fogged color for an array of vertices.
 150  * Input:  n - number of vertices
 151  *         v - array of vertices
 152  *         color - the original vertex colors
 153  * Output:  color - the fogged colors
 154  *
 155  */
 156 #define TAG(x) x##_raw
 157 #define CULLCHECK
 158 #define IDX 0
 159 #include "fog_tmp.h"
 160
 161 #define TAG(x) x##_masked
 162 #define CULLCHECK if (cullmask[i]&flag)
 163 #define IDX 1
 164 #include "fog_tmp.h"
 165
 166
 167 void
 168 _mesa_init_fog( void )
 169 {
 170    init_fog_tab_masked();
 171    init_fog_tab_raw();
 172 }
 173
 174
 175 /*
 176  * Compute fog for the vertices in the vertex buffer.
 177  */
 178 void
 179 _mesa_fog_vertices( struct vertex_buffer *VB )
 180 {
 181    GLcontext *ctx = VB->ctx;
 182    GLuint i = VB->CullMode & 1;
 183
 184    if (ctx->Visual->RGBAflag) {
 185       /* Fog RGB colors */
 186       if (ctx->TriangleCaps & DD_TRI_LIGHT_TWOSIDE) {
 187          fog_rgba_tab[i]( VB, 0, VERT_FACE_FRONT );
 188          fog_rgba_tab[i]( VB, 1, VERT_FACE_REAR );
 189       } else {
 190          fog_rgba_tab[i]( VB, 0, VERT_FACE_FRONT|VERT_FACE_REAR );
 191       }
 192    }
 193    else {
 194       /* Fog color indexes */
 195       if (ctx->TriangleCaps & DD_TRI_LIGHT_TWOSIDE) {
 196          fog_ci_tab[i]( VB, 0, VERT_FACE_FRONT );
 197          fog_ci_tab[i]( VB, 1, VERT_FACE_REAR );
 198       } else {
 199          fog_ci_tab[i]( VB, 0, VERT_FACE_FRONT|VERT_FACE_REAR );
 200       }
 201    }
 202 }
 203
 204
 205 static void check_fog_coords( GLcontext *ctx, struct gl_pipeline_stage *d )
 206 {
 207    d->type = 0;
 208
 209    if (ctx->FogMode==FOG_FRAGMENT)
 210    {
 211       d->type = PIPE_IMMEDIATE|PIPE_PRECALC;
 212       d->inputs = VERT_OBJ_ANY;
 213       d->outputs = VERT_FOG_COORD;
 214    }
 215 }
 216
 217 void gl_make_fog_coords( struct vertex_buffer *VB )
 218 {
 219    GLcontext *ctx = VB->ctx;
 220
 221    /* If full eye coords weren't required, just calculate the eye Z
 222     * values.
 223     */
 224    if (!ctx->NeedEyeCoords) {
 225       GLfloat *m = ctx->ModelView.m;
 226       GLfloat plane[4];
 227
 228       plane[0] = m[2];
 229       plane[1] = m[6];
 230       plane[2] = m[10];
 231       plane[3] = m[14];
 232
 233       gl_dotprod_tab[0][VB->ObjPtr->size](&VB->Eye,
 234                                           2, /* fill z coordinates */
 235                                           VB->ObjPtr,
 236                                           plane,
 237                                           0 );
 238
 239       make_fog_coord_tab[0]( VB, &VB->Eye, 0 );
 240    }
 241    else
 242    {
 243       make_fog_coord_tab[0]( VB, VB->EyePtr, 0 );
 244    }
 245 }
 246
 247
 248 /* Drivers that want fog coordinates in VB->Spec[0] alpha, can substitute this
 249  * stage for the default PIPE_OP_FOG pipeline stage.
 250  */
 251 struct gl_pipeline_stage gl_fog_coord_stage = {
 252    "build fog coordinates",
 253    PIPE_OP_FOG,
 254    PIPE_PRECALC|PIPE_IMMEDIATE,
 255    0,
 256    NEW_FOG,
 257    NEW_LIGHTING|NEW_RASTER_OPS|NEW_FOG|NEW_MODELVIEW,
 258    0, 0,
 259    0, 0, 0,
 260    check_fog_coords,
 261    gl_make_fog_coords
 262 };
 263
 264
 265
 266
 267
 268 /*
 269  * Apply fog to an array of RGBA pixels.
 270  * Input:  n - number of pixels
 271  *         z - array of integer depth values
 272  *         red, green, blue, alpha - pixel colors
 273  * Output:  red, green, blue, alpha - fogged pixel colors
 274  */
 275 void
 276 _mesa_fog_rgba_pixels( const GLcontext *ctx,
 277                        GLuint n, const GLdepth z[], GLubyte rgba[][4] )
 278 {
 279    GLfloat c = ctx->ProjectionMatrix.m[10];
 280    GLfloat d = ctx->ProjectionMatrix.m[14];
 281    GLuint i;
 282
 283    GLfloat rFog = ctx->Fog.Color[0] * 255.0F;
 284    GLfloat gFog = ctx->Fog.Color[1] * 255.0F;
 285    GLfloat bFog = ctx->Fog.Color[2] * 255.0F;
 286
 287    GLfloat tz = ctx->Viewport.WindowMap.m[MAT_TZ];
 288    GLfloat szInv = 1.0F / ctx->Viewport.WindowMap.m[MAT_SZ];
 289
 290    switch (ctx->Fog.Mode) {
 291       case GL_LINEAR:
 292          {
 293             GLfloat fogEnd = ctx->Fog.End;
 294             GLfloat fogScale = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
 295             for (i=0;i<n;i++) {
 296                GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 297                GLfloat eyez = -d / (c+ndcz);
 298                GLfloat f, g;
 299                if (eyez < 0.0)  eyez = -eyez;
 300                f = (fogEnd - eyez) * fogScale;
 301                f = CLAMP( f, 0.0F, 1.0F );
 302                g = 1.0F - f;
 303                rgba[i][RCOMP] = (GLint) (f * rgba[i][RCOMP] + g * rFog);
 304                rgba[i][GCOMP] = (GLint) (f * rgba[i][GCOMP] + g * gFog);
 305                rgba[i][BCOMP] = (GLint) (f * rgba[i][BCOMP] + g * bFog);
 306             }
 307          }
 308          break;
 309       case GL_EXP:
 310          for (i=0;i<n;i++) {
 311             GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 312             GLfloat eyez = d / (c+ndcz);
 313             GLfloat f, g;
 314             if (eyez < 0.0)
 315                eyez = -eyez;
 316             f = exp( -ctx->Fog.Density * eyez );
 317             g = 1.0F - f;
 318             rgba[i][RCOMP] = (GLint) (f * rgba[i][RCOMP] + g * rFog);
 319             rgba[i][GCOMP] = (GLint) (f * rgba[i][GCOMP] + g * gFog);
 320             rgba[i][BCOMP] = (GLint) (f * rgba[i][BCOMP] + g * bFog);
 321          }
 322          break;
 323       case GL_EXP2:
 324          {
 325             GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
 326             for (i=0;i<n;i++) {
 327                GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 328                GLfloat eyez = d / (c+ndcz);
 329                GLfloat f, g;
 330                GLfloat tmp = negDensitySquared * eyez * eyez;
 331 #ifdef __alpha__
 332                /* XXX this underflow check may be needed for other systems */
 333                if (tmp < FLT_MIN_10_EXP)
 334                   f = exp( FLT_MIN_10_EXP );
 335                else
 336 #endif
 337                   f = exp( tmp );
 338                g = 1.0F - f;
 339                rgba[i][RCOMP] = (GLint) (f * rgba[i][RCOMP] + g * rFog);
 340                rgba[i][GCOMP] = (GLint) (f * rgba[i][GCOMP] + g * gFog);
 341                rgba[i][BCOMP] = (GLint) (f * rgba[i][BCOMP] + g * bFog);
 342             }
 343          }
 344          break;
 345       default:
 346          gl_problem(ctx, "Bad fog mode in _mesa_fog_rgba_pixels");
 347          return;
 348    }
 349 }
 350
 351
 352
 353
 354 /*
 355  * Apply fog to an array of color index pixels.
 356  * Input:  n - number of pixels
 357  *         z - array of integer depth values
 358  *         index - pixel color indexes
 359  * Output:  index - fogged pixel color indexes
 360  */
 361 void
 362 _mesa_fog_ci_pixels( const GLcontext *ctx,
 363                      GLuint n, const GLdepth z[], GLuint index[] )
 364 {
 365    GLfloat c = ctx->ProjectionMatrix.m[10];
 366    GLfloat d = ctx->ProjectionMatrix.m[14];
 367    GLuint i;
 368
 369    GLfloat tz = ctx->Viewport.WindowMap.m[MAT_TZ];
 370    GLfloat szInv = 1.0F / ctx->Viewport.WindowMap.m[MAT_SZ];
 371
 372    switch (ctx->Fog.Mode) {
 373       case GL_LINEAR:
 374          {
 375             GLfloat fogEnd = ctx->Fog.End;
 376             GLfloat fogScale = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
 377             for (i=0;i<n;i++) {
 378                GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 379                GLfloat eyez = -d / (c+ndcz);
 380                GLfloat f;
 381                if (eyez < 0.0)  eyez = -eyez;
 382                f = (fogEnd - eyez) * fogScale;
 383                f = CLAMP( f, 0.0F, 1.0F );
 384                index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
 385             }
 386          }
 387          break;
 388       case GL_EXP:
 389          for (i=0;i<n;i++) {
 390             GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 391             GLfloat eyez = -d / (c+ndcz);
 392             GLfloat f;
 393             if (eyez < 0.0)
 394                eyez = -eyez;
 395             f = exp( -ctx->Fog.Density * eyez );
 396             f = CLAMP( f, 0.0F, 1.0F );
 397             index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
 398          }
 399          break;
 400       case GL_EXP2:
 401          {
 402             GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
 403             for (i=0;i<n;i++) {
 404                GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 405                GLfloat eyez = -d / (c+ndcz);
 406                GLfloat tmp, f;
 407                if (eyez < 0.0)
 408                   eyez = -eyez;
 409                tmp = negDensitySquared * eyez * eyez;
 410 #ifdef __alpha__
 411                /* XXX this underflow check may be needed for other systems */
 412                if (tmp < FLT_MIN_10_EXP)
 413                   f = exp( FLT_MIN_10_EXP );
 414                else
 415 #endif
 416                f = exp( tmp );
 417                f = CLAMP( f, 0.0F, 1.0F );
 418                index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
 419             }
 420          }
 421          break;
 422       default:
 423          gl_problem(ctx, "Bad fog mode in _mesa_fog_ci_pixels");
 424          return;
 425    }
 426 }
 427