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