src/mesa/main/fog.c

   1 /* $Id: fog.c,v 1.4 1999/11/11 01:22:26 brianp Exp $ */
   2
   3 /*
   4  * Mesa 3-D graphics library
   5  * Version:  3.3
   6  *
   7  * Copyright (C) 1999  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 #endif
  38
  39
  40
  41 void
  42 _mesa_Fogf(GLenum pname, GLfloat param)
  43 {
  44    _mesa_Fogfv(pname, &param);
  45 }
  46
  47
  48 void
  49 _mesa_Fogi(GLenum pname, GLint param )
  50 {
  51    GLfloat fparam = (GLfloat) param;
  52    _mesa_Fogfv(pname, &fparam);
  53 }
  54
  55
  56 void
  57 _mesa_Fogiv(GLenum pname, const GLint *params )
  58 {
  59    GLfloat p[4];
  60    switch (pname) {
  61       case GL_FOG_MODE:
  62       case GL_FOG_DENSITY:
  63       case GL_FOG_START:
  64       case GL_FOG_END:
  65       case GL_FOG_INDEX:
  66          p[0] = (GLfloat) *params;
  67          break;
  68       case GL_FOG_COLOR:
  69          p[0] = INT_TO_FLOAT( params[0] );
  70          p[1] = INT_TO_FLOAT( params[1] );
  71          p[2] = INT_TO_FLOAT( params[2] );
  72          p[3] = INT_TO_FLOAT( params[3] );
  73          break;
  74       default:
  75          /* Error will be caught later in gl_Fogfv */
  76          ;
  77    }
  78    _mesa_Fogfv(pname, p);
  79 }
  80
  81
  82 void
  83 _mesa_Fogfv( GLenum pname, const GLfloat *params )
  84 {
  85    GET_CURRENT_CONTEXT(ctx);
  86    GLenum m;
  87
  88    switch (pname) {
  89       case GL_FOG_MODE:
  90          m = (GLenum) (GLint) *params;
  91          if (m==GL_LINEAR || m==GL_EXP || m==GL_EXP2) {
  92             ctx->Fog.Mode = m;
  93          }
  94          else {
  95             gl_error( ctx, GL_INVALID_ENUM, "glFog" );
  96             return;
  97          }
  98          break;
  99       case GL_FOG_DENSITY:
 100          if (*params<0.0) {
 101             gl_error( ctx, GL_INVALID_VALUE, "glFog" );
 102             return;
 103          }
 104          else {
 105             ctx->Fog.Density = *params;
 106          }
 107          break;
 108       case GL_FOG_START:
 109 #if 0
 110          /* Prior to OpenGL 1.1, this was an error */
 111          if (*params<0.0F) {
 112             gl_error( ctx, GL_INVALID_VALUE, "glFog(GL_FOG_START)" );
 113             return;
 114          }
 115 #endif
 116          ctx->Fog.Start = *params;
 117          break;
 118       case GL_FOG_END:
 119 #if 0
 120          /* Prior to OpenGL 1.1, this was an error */
 121          if (*params<0.0F) {
 122             gl_error( ctx, GL_INVALID_VALUE, "glFog(GL_FOG_END)" );
 123             return;
 124          }
 125 #endif
 126          ctx->Fog.End = *params;
 127          break;
 128       case GL_FOG_INDEX:
 129          ctx->Fog.Index = *params;
 130          break;
 131       case GL_FOG_COLOR:
 132          ctx->Fog.Color[0] = params[0];
 133          ctx->Fog.Color[1] = params[1];
 134          ctx->Fog.Color[2] = params[2];
 135          ctx->Fog.Color[3] = params[3];
 136          break;
 137       default:
 138          gl_error( ctx, GL_INVALID_ENUM, "glFog" );
 139          return;
 140    }
 141
 142    if (ctx->Driver.Fogfv) {
 143       (*ctx->Driver.Fogfv)( ctx, pname, params );
 144    }
 145
 146    ctx->NewState |= NEW_FOG;
 147 }
 148
 149
 150 typedef void (*fog_func)( struct vertex_buffer *VB, GLuint side,
 151                           GLubyte flag );
 152
 153
 154 static fog_func fog_ci_tab[2];
 155 static fog_func fog_rgba_tab[2];
 156
 157 /*
 158  * Compute the fogged color for an array of vertices.
 159  * Input:  n - number of vertices
 160  *         v - array of vertices
 161  *         color - the original vertex colors
 162  * Output:  color - the fogged colors
 163  *
 164  */
 165 #define TAG(x) x##_raw
 166 #define CULLCHECK
 167 #define IDX 0
 168 #include "fog_tmp.h"
 169
 170 #define TAG(x) x##_masked
 171 #define CULLCHECK if (cullmask[i]&flag)
 172 #define IDX 1
 173 #include "fog_tmp.h"
 174
 175 void gl_init_fog( void )
 176 {
 177    init_fog_tab_masked();
 178    init_fog_tab_raw();
 179 }
 180
 181 /*
 182  * Compute fog for the vertices in the vertex buffer.
 183  */
 184 void gl_fog_vertices( struct vertex_buffer *VB )
 185 {
 186    GLcontext *ctx = VB->ctx;
 187    GLuint i = VB->CullMode & 1;
 188
 189    if (ctx->Visual->RGBAflag) {
 190       /* Fog RGB colors */
 191       if (ctx->TriangleCaps & DD_TRI_LIGHT_TWOSIDE) {
 192          fog_rgba_tab[i]( VB, 0, VERT_FACE_FRONT );
 193          fog_rgba_tab[i]( VB, 1, VERT_FACE_REAR );
 194       } else {
 195          fog_rgba_tab[i]( VB, 0, VERT_FACE_FRONT|VERT_FACE_REAR );
 196       }
 197    }
 198    else {
 199       /* Fog color indexes */
 200       if (ctx->TriangleCaps & DD_TRI_LIGHT_TWOSIDE) {
 201          fog_ci_tab[i]( VB, 0, VERT_FACE_FRONT );
 202          fog_ci_tab[i]( VB, 1, VERT_FACE_REAR );
 203       } else {
 204          fog_ci_tab[i]( VB, 0, VERT_FACE_FRONT|VERT_FACE_REAR );
 205       }
 206    }
 207 }
 208
 209 /*
 210  * Apply fog to an array of RGBA pixels.
 211  * Input:  n - number of pixels
 212  *         z - array of integer depth values
 213  *         red, green, blue, alpha - pixel colors
 214  * Output:  red, green, blue, alpha - fogged pixel colors
 215  */
 216 void gl_fog_rgba_pixels( const GLcontext *ctx,
 217                          GLuint n, const GLdepth z[], GLubyte rgba[][4] )
 218 {
 219    GLfloat c = ctx->ProjectionMatrix.m[10];
 220    GLfloat d = ctx->ProjectionMatrix.m[14];
 221    GLuint i;
 222
 223    GLfloat rFog = ctx->Fog.Color[0] * 255.0F;
 224    GLfloat gFog = ctx->Fog.Color[1] * 255.0F;
 225    GLfloat bFog = ctx->Fog.Color[2] * 255.0F;
 226
 227    GLfloat tz = ctx->Viewport.WindowMap.m[MAT_TZ];
 228    GLfloat szInv = 1.0F / ctx->Viewport.WindowMap.m[MAT_SZ];
 229
 230    switch (ctx->Fog.Mode) {
 231       case GL_LINEAR:
 232          {
 233             GLfloat fogEnd = ctx->Fog.End;
 234             GLfloat fogScale = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
 235             for (i=0;i<n;i++) {
 236                GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 237                GLfloat eyez = -d / (c+ndcz);
 238                GLfloat f, g;
 239                if (eyez < 0.0)  eyez = -eyez;
 240                f = (fogEnd - eyez) * fogScale;
 241                f = CLAMP( f, 0.0F, 1.0F );
 242                g = 1.0F - f;
 243                rgba[i][RCOMP] = (GLint) (f * rgba[i][RCOMP] + g * rFog);
 244                rgba[i][GCOMP] = (GLint) (f * rgba[i][GCOMP] + g * gFog);
 245                rgba[i][BCOMP] = (GLint) (f * rgba[i][BCOMP] + g * bFog);
 246             }
 247          }
 248          break;
 249       case GL_EXP:
 250          for (i=0;i<n;i++) {
 251             GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 252             GLfloat eyez = d / (c+ndcz);
 253             GLfloat f, g;
 254             if (eyez < 0.0)
 255                eyez = -eyez;
 256             f = exp( -ctx->Fog.Density * eyez );
 257             g = 1.0F - f;
 258             rgba[i][RCOMP] = (GLint) (f * rgba[i][RCOMP] + g * rFog);
 259             rgba[i][GCOMP] = (GLint) (f * rgba[i][GCOMP] + g * gFog);
 260             rgba[i][BCOMP] = (GLint) (f * rgba[i][BCOMP] + g * bFog);
 261          }
 262          break;
 263       case GL_EXP2:
 264          {
 265             GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
 266             for (i=0;i<n;i++) {
 267                GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 268                GLfloat eyez = d / (c+ndcz);
 269                GLfloat f, g;
 270                GLfloat tmp = negDensitySquared * eyez * eyez;
 271 #ifdef __alpha__
 272                /* XXX this underflow check may be needed for other systems */
 273                if (tmp < FLT_MIN_10_EXP)
 274                   f = exp( FLT_MIN_10_EXP );
 275                else
 276 #endif
 277                   f = exp( tmp );
 278                g = 1.0F - f;
 279                rgba[i][RCOMP] = (GLint) (f * rgba[i][RCOMP] + g * rFog);
 280                rgba[i][GCOMP] = (GLint) (f * rgba[i][GCOMP] + g * gFog);
 281                rgba[i][BCOMP] = (GLint) (f * rgba[i][BCOMP] + g * bFog);
 282             }
 283          }
 284          break;
 285       default:
 286          gl_problem(ctx, "Bad fog mode in gl_fog_rgba_pixels");
 287          return;
 288    }
 289 }
 290
 291
 292
 293
 294 /*
 295  * Apply fog to an array of color index pixels.
 296  * Input:  n - number of pixels
 297  *         z - array of integer depth values
 298  *         index - pixel color indexes
 299  * Output:  index - fogged pixel color indexes
 300  */
 301 void gl_fog_ci_pixels( const GLcontext *ctx,
 302                        GLuint n, const GLdepth z[], GLuint index[] )
 303 {
 304    GLfloat c = ctx->ProjectionMatrix.m[10];
 305    GLfloat d = ctx->ProjectionMatrix.m[14];
 306    GLuint i;
 307
 308    GLfloat tz = ctx->Viewport.WindowMap.m[MAT_TZ];
 309    GLfloat szInv = 1.0F / ctx->Viewport.WindowMap.m[MAT_SZ];
 310
 311    switch (ctx->Fog.Mode) {
 312       case GL_LINEAR:
 313          {
 314             GLfloat fogEnd = ctx->Fog.End;
 315             GLfloat fogScale = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
 316             for (i=0;i<n;i++) {
 317                GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 318                GLfloat eyez = -d / (c+ndcz);
 319                GLfloat f;
 320                if (eyez < 0.0)  eyez = -eyez;
 321                f = (fogEnd - eyez) * fogScale;
 322                f = CLAMP( f, 0.0F, 1.0F );
 323                index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
 324             }
 325          }
 326          break;
 327       case GL_EXP:
 328          for (i=0;i<n;i++) {
 329             GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 330             GLfloat eyez = -d / (c+ndcz);
 331             GLfloat f;
 332             if (eyez < 0.0)
 333                eyez = -eyez;
 334             f = exp( -ctx->Fog.Density * eyez );
 335             f = CLAMP( f, 0.0F, 1.0F );
 336             index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
 337          }
 338          break;
 339       case GL_EXP2:
 340          {
 341             GLfloat negDensitySquared = -ctx->Fog.Density * ctx->Fog.Density;
 342             for (i=0;i<n;i++) {
 343                GLfloat ndcz = ((GLfloat) z[i] - tz) * szInv;
 344                GLfloat eyez = -d / (c+ndcz);
 345                GLfloat tmp, f;
 346                if (eyez < 0.0)
 347                   eyez = -eyez;
 348                tmp = negDensitySquared * eyez * eyez;
 349 #ifdef __alpha__
 350                /* XXX this underflow check may be needed for other systems */
 351                if (tmp < FLT_MIN_10_EXP)
 352                   f = exp( FLT_MIN_10_EXP );
 353                else
 354 #endif
 355                f = exp( tmp );
 356                f = CLAMP( f, 0.0F, 1.0F );
 357                index[i] = (GLuint) ((GLfloat) index[i] + (1.0F-f) * ctx->Fog.Index);
 358             }
 359          }
 360          break;
 361       default:
 362          gl_problem(ctx, "Bad fog mode in gl_fog_ci_pixels");
 363          return;
 364    }
 365 }
 366