progs/demos/fogcoord.c

   1 /*
   2  * EXT_fog_coord.
   3  *
   4  * Based on glutskel.c by Brian Paul
   5  * and NeHe's Volumetric fog tutorial!
   6  *
   7  * Daniel Borca
   8  */
   9
  10 #define GL_GLEXT_PROTOTYPES
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <math.h>
  14 #include <GL/glut.h>
  15
  16 #define DEPTH 5.0f
  17
  18 static PFNGLFOGCOORDFEXTPROC glFogCoordf_ext;
  19 static PFNGLFOGCOORDPOINTEREXTPROC glFogCoordPointer_ext;
  20
  21 static GLboolean have_fog_coord;
  22
  23 static GLfloat camz;
  24
  25 static GLint fogMode;
  26 static GLboolean fogCoord;
  27 static GLfloat fogDensity = 0.75;
  28 static GLfloat fogStart = 1.0, fogEnd = DEPTH;
  29 static GLfloat fogColor[4] = {0.6f, 0.3f, 0.0f, 1.0f};
  30 static const char *ModeStr = NULL;
  31 static GLboolean Arrays = GL_FALSE;
  32 static GLboolean Texture = GL_TRUE;
  33
  34
  35 static void
  36 Reset(void)
  37 {
  38    fogMode = 1;
  39    fogCoord = 1;
  40    fogDensity = 0.75;
  41    fogStart = 1.0;
  42    fogEnd = DEPTH;
  43    Arrays = GL_FALSE;
  44    Texture = GL_TRUE;
  45 }
  46
  47
  48 static void APIENTRY
  49 glFogCoordf_nop (GLfloat f)
  50 {
  51    (void)f;
  52 }
  53
  54
  55 static void
  56 PrintString(const char *s)
  57 {
  58    while (*s) {
  59       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  60       s++;
  61    }
  62 }
  63
  64
  65 static void
  66 PrintInfo(void)
  67 {
  68    char s[100];
  69
  70    glDisable(GL_FOG);
  71    glColor3f(0, 1, 1);
  72
  73    sprintf(s, "Mode(m): %s  Start(s/S): %g  End(e/E): %g  Density(d/D): %g",
  74            ModeStr, fogStart, fogEnd, fogDensity);
  75    glWindowPos2iARB(5, 20);
  76    PrintString(s);
  77
  78    sprintf(s, "Arrays(a): %s  glFogCoord(c): %s  EyeZ(z/z): %g",
  79            (Arrays ? "Yes" : "No"),
  80            (fogCoord ? "Yes" : "No"),
  81            camz);
  82    glWindowPos2iARB(5, 5);
  83    PrintString(s);
  84 }
  85
  86
  87 static int
  88 SetFogMode(GLint fogMode)
  89 {
  90    fogMode &= 3;
  91    switch (fogMode) {
  92    case 0:
  93       ModeStr = "Off";
  94       glDisable(GL_FOG);
  95       break;
  96    case 1:
  97       ModeStr = "GL_LINEAR";
  98       glEnable(GL_FOG);
  99       glFogi(GL_FOG_MODE, GL_LINEAR);
 100       glFogf(GL_FOG_START, fogStart);
 101       glFogf(GL_FOG_END, fogEnd);
 102       break;
 103    case 2:
 104       ModeStr = "GL_EXP";
 105       glEnable(GL_FOG);
 106       glFogi(GL_FOG_MODE, GL_EXP);
 107       glFogf(GL_FOG_DENSITY, fogDensity);
 108       break;
 109    case 3:
 110       ModeStr = "GL_EXP2";
 111       glEnable(GL_FOG);
 112       glFogi(GL_FOG_MODE, GL_EXP2);
 113       glFogf(GL_FOG_DENSITY, fogDensity);
 114       break;
 115    }
 116    return fogMode;
 117 }
 118
 119
 120 static GLboolean
 121 SetFogCoord(GLboolean fogCoord)
 122 {
 123    glFogCoordf_ext = glFogCoordf_nop;
 124
 125    if (!have_fog_coord) {
 126       return GL_FALSE;
 127    }
 128
 129    if (fogCoord) {
 130       glFogCoordf_ext = (PFNGLFOGCOORDFEXTPROC)glutGetProcAddress("glFogCoordfEXT");
 131       glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
 132    }
 133    else {
 134       glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FRAGMENT_DEPTH_EXT);
 135    }
 136    return fogCoord;
 137 }
 138
 139
 140 /* could reuse vertices */
 141 static GLuint vertex_index[] = {
 142    /* Back */
 143    0, 1, 2, 3,
 144
 145    /* Floor */
 146    4, 5, 6, 7,
 147
 148    /* Roof */
 149    8, 9, 10, 11,
 150
 151    /* Right */
 152    12, 13, 14, 15,
 153
 154    /* Left */
 155    16, 17, 18, 19
 156 };
 157
 158 static GLfloat vertex_pointer[][3] = {
 159    /* Back */
 160    {-1.0f,-1.0f,-DEPTH}, { 1.0f,-1.0f,-DEPTH}, { 1.0f, 1.0f,-DEPTH}, {-1.0f, 1.0f,-DEPTH},
 161
 162    /* Floor */
 163    {-1.0f,-1.0f,-DEPTH}, { 1.0f,-1.0f,-DEPTH}, { 1.0f,-1.0f, 0.0}, {-1.0f,-1.0f, 0.0},
 164
 165    /* Roof */
 166    {-1.0f, 1.0f,-DEPTH}, { 1.0f, 1.0f,-DEPTH}, { 1.0f, 1.0f, 0.0}, {-1.0f, 1.0f, 0.0},
 167
 168    /* Right */
 169    { 1.0f,-1.0f, 0.0}, { 1.0f, 1.0f, 0.0}, { 1.0f, 1.0f,-DEPTH}, { 1.0f,-1.0f,-DEPTH},
 170
 171    /* Left */
 172    {-1.0f,-1.0f, 0.0}, {-1.0f, 1.0f, 0.0}, {-1.0f, 1.0f,-DEPTH}, {-1.0f,-1.0f,-DEPTH}
 173 };
 174
 175 static GLfloat texcoord_pointer[][2] = {
 176    /* Back */
 177    {0.0f, 0.0f}, {1.0f, 0.0f}, {1.0f, 1.0f}, {0.0f, 1.0f},
 178
 179    /* Floor */
 180    {0.0f, 0.0f}, {1.0f, 0.0f}, {1.0f, DEPTH}, {0.0f, DEPTH},
 181
 182    /* Roof */
 183    {1.0f, 0.0f}, {0.0f, 0.0f}, {0.0f, DEPTH}, {1.0f, DEPTH},
 184
 185    /* Right */
 186    {0.0f, 1.0f}, {0.0f, 0.0f}, {DEPTH, 0.0f}, {DEPTH, 1.0f},
 187
 188    /* Left */
 189    {0.0f, 0.0f}, {0.0f, 1.0f}, {DEPTH, 1.0f}, {DEPTH, 0.0f}
 190 };
 191
 192 static GLfloat fogcoord_pointer[] = {
 193    /* Back */
 194    DEPTH, DEPTH, DEPTH, DEPTH,
 195
 196    /* Floor */
 197    DEPTH, DEPTH, 0.0, 0.0,
 198
 199    /* Roof */
 200    DEPTH, DEPTH, 0.0, 0.0,
 201
 202    /* Right */
 203    0.0, 0.0, DEPTH, DEPTH,
 204
 205    /* Left */
 206    0.0, 0.0, DEPTH, DEPTH
 207 };
 208
 209
 210 static void
 211 Display( void )
 212 {
 213    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 214    glLoadIdentity ();
 215
 216    glTranslatef(0.0f, 0.0f, -camz);
 217
 218    SetFogMode(fogMode);
 219
 220    glColor3f(1, 1, 1);
 221
 222    if (Texture)
 223       glEnable(GL_TEXTURE_2D);
 224
 225    if (Arrays) {
 226       glEnableClientState(GL_VERTEX_ARRAY);
 227       glEnableClientState(GL_TEXTURE_COORD_ARRAY);
 228       glDrawElements(GL_QUADS, sizeof(vertex_index) / sizeof(vertex_index[0]),
 229                      GL_UNSIGNED_INT, vertex_index);
 230       glDisableClientState(GL_VERTEX_ARRAY);
 231       glDisableClientState(GL_TEXTURE_COORD_ARRAY);
 232    }
 233    else {
 234       /* Back */
 235       glBegin(GL_QUADS);
 236       glFogCoordf_ext(DEPTH); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f,-DEPTH);
 237       glFogCoordf_ext(DEPTH); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f,-DEPTH);
 238       glFogCoordf_ext(DEPTH); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f,-DEPTH);
 239       glFogCoordf_ext(DEPTH); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f,-DEPTH);
 240       glEnd();
 241
 242       /* Floor */
 243       glBegin(GL_QUADS);
 244       glFogCoordf_ext(DEPTH); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f,-DEPTH);
 245       glFogCoordf_ext(DEPTH); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f,-DEPTH);
 246       glFogCoordf_ext(0.0f); glTexCoord2f(1.0f,  DEPTH); glVertex3f( 1.0f,-1.0f,0.0);
 247       glFogCoordf_ext(0.0f); glTexCoord2f(0.0f,  DEPTH); glVertex3f(-1.0f,-1.0f,0.0);
 248       glEnd();
 249
 250       /* Roof */
 251       glBegin(GL_QUADS);
 252       glFogCoordf_ext(DEPTH); glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, 1.0f,-DEPTH);
 253       glFogCoordf_ext(DEPTH); glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, 1.0f,-DEPTH);
 254       glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, DEPTH); glVertex3f( 1.0f, 1.0f,0.0);
 255       glFogCoordf_ext(0.0f); glTexCoord2f(1.0f, DEPTH); glVertex3f(-1.0f, 1.0f,0.0);
 256       glEnd();
 257
 258       /* Right */
 259       glBegin(GL_QUADS);
 260       glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f,-1.0f,0.0);
 261       glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, 1.0f,0.0);
 262       glFogCoordf_ext(DEPTH); glTexCoord2f(DEPTH, 0.0f); glVertex3f( 1.0f, 1.0f,-DEPTH);
 263       glFogCoordf_ext(DEPTH); glTexCoord2f(DEPTH, 1.0f); glVertex3f( 1.0f,-1.0f,-DEPTH);
 264       glEnd();
 265
 266       /* Left */
 267       glBegin(GL_QUADS);
 268       glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f,0.0);
 269       glFogCoordf_ext(0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f,0.0);
 270       glFogCoordf_ext(DEPTH); glTexCoord2f(DEPTH, 1.0f); glVertex3f(-1.0f, 1.0f,-DEPTH);
 271       glFogCoordf_ext(DEPTH); glTexCoord2f(DEPTH, 0.0f); glVertex3f(-1.0f,-1.0f,-DEPTH);
 272       glEnd();
 273    }
 274
 275    glDisable(GL_TEXTURE_2D);
 276
 277    PrintInfo();
 278
 279    glutSwapBuffers();
 280 }
 281
 282
 283 static void
 284 Reshape( int width, int height )
 285 {
 286    glViewport(0, 0, width, height);
 287    glMatrixMode(GL_PROJECTION);
 288    glLoadIdentity();
 289    glFrustum(-1, 1, -1, 1, 1.0, 100);
 290    glMatrixMode(GL_MODELVIEW);
 291    glLoadIdentity();
 292 }
 293
 294
 295 static void
 296 Key( unsigned char key, int x, int y )
 297 {
 298    (void) x;
 299    (void) y;
 300    switch (key) {
 301       case 'a':
 302          Arrays = !Arrays;
 303          break;
 304       case 'f':
 305       case 'm':
 306          fogMode = SetFogMode(fogMode + 1);
 307          break;
 308       case 'D':
 309          fogDensity += 0.05;
 310          SetFogMode(fogMode);
 311          break;
 312       case 'd':
 313          if (fogDensity > 0.0) {
 314             fogDensity -= 0.05;
 315          }
 316          SetFogMode(fogMode);
 317          break;
 318       case 's':
 319          if (fogStart > 0.0) {
 320             fogStart -= 0.25;
 321          }
 322          SetFogMode(fogMode);
 323          break;
 324       case 'S':
 325          if (fogStart < 100.0) {
 326             fogStart += 0.25;
 327          }
 328          SetFogMode(fogMode);
 329          break;
 330       case 'e':
 331          if (fogEnd > 0.0) {
 332             fogEnd -= 0.25;
 333          }
 334          SetFogMode(fogMode);
 335          break;
 336       case 'E':
 337          if (fogEnd < 100.0) {
 338             fogEnd += 0.25;
 339          }
 340          SetFogMode(fogMode);
 341          break;
 342       case 'c':
 343          fogCoord = SetFogCoord(fogCoord ^ GL_TRUE);
 344          break;
 345       case 't':
 346          Texture = !Texture;
 347          break;
 348       case 'z':
 349          camz -= 0.1;
 350          break;
 351       case 'Z':
 352          camz += 0.1;
 353          break;
 354       case 'r':
 355          Reset();
 356          break;
 357       case 27:
 358          exit(0);
 359          break;
 360    }
 361    glutPostRedisplay();
 362 }
 363
 364
 365 static void
 366 Init(void)
 367 {
 368    static const GLubyte teximage[2][2][4] = {
 369       { { 255, 255, 255, 255}, { 128, 128, 128, 255} },
 370       { { 128, 128, 128, 255}, { 255, 255, 255, 255} }
 371    };
 372
 373    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 374
 375    have_fog_coord = glutExtensionSupported("GL_EXT_fog_coord");
 376    if (!have_fog_coord) {
 377       printf("GL_EXT_fog_coord not supported!\n");
 378    }
 379
 380    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 2, 2, 0,
 381                 GL_RGBA, GL_UNSIGNED_BYTE, teximage);
 382    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 383    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
 384
 385    glClearColor(0.1f, 0.1f, 0.1f, 0.0f);
 386
 387    glDepthFunc(GL_LEQUAL);
 388    glEnable(GL_DEPTH_TEST);
 389    glShadeModel(GL_SMOOTH);
 390    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
 391
 392    glFogfv(GL_FOG_COLOR, fogColor);
 393    glHint(GL_FOG_HINT, GL_NICEST);
 394    fogCoord = SetFogCoord(GL_TRUE); /* try to enable fog_coord */
 395    fogMode = SetFogMode(1);
 396
 397    glEnableClientState(GL_VERTEX_ARRAY);
 398    glVertexPointer(3, GL_FLOAT, 0, vertex_pointer);
 399
 400    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
 401    glTexCoordPointer(2, GL_FLOAT, 0, texcoord_pointer);
 402
 403    if (have_fog_coord) {
 404       glFogCoordPointer_ext = (PFNGLFOGCOORDPOINTEREXTPROC)glutGetProcAddress("glFogCoordPointerEXT");
 405       glEnableClientState(GL_FOG_COORDINATE_ARRAY_EXT);
 406       glFogCoordPointer_ext(GL_FLOAT, 0, fogcoord_pointer);
 407    }
 408
 409    Reset();
 410 }
 411
 412
 413 int
 414 main( int argc, char *argv[] )
 415 {
 416    glutInit( &argc, argv );
 417    glutInitWindowSize( 600, 600 );
 418    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
 419    glutCreateWindow(argv[0]);
 420    glutReshapeFunc( Reshape );
 421    glutKeyboardFunc( Key );
 422    glutDisplayFunc( Display );
 423    Init();
 424    glutMainLoop();
 425    return 0;
 426 }