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