src/demos/pointblast.c

   1
   2 /* Copyright (c) Mark J. Kilgard, 1997.  */
   3
   4 /* This program is freely distributable without licensing fees
   5    and is provided without guarantee or warrantee expressed or
   6    implied. This program is -not- in the public domain. */
   7
   8 /* This example demonstrates how to render particle effects
   9    with OpenGL.  A cloud of pinkish/orange particles explodes with the
  10    particles bouncing off the ground.  When the EXT_point_parameters
  11    is present , the particle size is attenuated based on eye distance. */
  12
  13
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <math.h>       /* for cos(), sin(), and sqrt() */
  18 #ifdef _WIN32
  19 #include <windows.h>
  20 #endif
  21 #include <GL/glew.h>
  22 #include "glut_wrap.h"
  23
  24 /* Some <math.h> files do not define M_PI... */
  25 #ifndef M_PI
  26 #define M_PI 3.14159265
  27 #endif
  28
  29 #if 0  /* For debugging. */
  30 #undef GL_EXT_point_parameters
  31 #endif
  32
  33 static GLfloat angle = -150;   /* in degrees */
  34 static int spin = 0;
  35 static int moving, begin;
  36 static int newModel = 1;
  37 static float theTime;
  38 static int repeat = 1;
  39 static int blend = 1;
  40 int useMipmaps = 1;
  41 int linearFiltering = 1;
  42
  43 static GLfloat constant[3] = { 1/5.0, 0.0, 0.0 };
  44 static GLfloat linear[3] = { 0.0, 1/5.0, 0.0 };
  45 static GLfloat theQuad[3] = { 0.25, 0.0, 1/60.0 };
  46
  47 #define MAX_POINTS 2000
  48
  49 static int numPoints = 200;
  50
  51 static GLfloat pointList[MAX_POINTS][3];
  52 static GLfloat pointTime[MAX_POINTS];
  53 static GLfloat pointVelocity[MAX_POINTS][2];
  54 static GLfloat pointDirection[MAX_POINTS][2];
  55 static int colorList[MAX_POINTS];
  56 static int animate = 1, motion = 0;
  57
  58 static GLfloat colorSet[][4] = {
  59   /* Shades of red. */
  60   { 0.7, 0.2, 0.4, 0.5 },
  61   { 0.8, 0.0, 0.7, 0.5 },
  62   { 1.0, 0.0, 0.0, 0.5 },
  63   { 0.9, 0.3, 0.6, 0.5 },
  64   { 1.0, 0.4, 0.0, 0.5 },
  65   { 1.0, 0.0, 0.5, 0.5 },
  66 };
  67
  68 #define NUM_COLORS (sizeof(colorSet)/sizeof(colorSet[0]))
  69
  70 #define DEAD (NUM_COLORS+1)
  71
  72
  73 #if 0  /* drand48 might be better on Unix machines */
  74 #define RANDOM_RANGE(lo, hi) ((lo) + (hi - lo) * drand48())
  75 #else
  76 static float float_rand(void) { return rand() / (float) RAND_MAX; }
  77 #define RANDOM_RANGE(lo, hi) ((lo) + (hi - lo) * float_rand())
  78 #endif
  79
  80 #define MEAN_VELOCITY 3.0
  81 #define GRAVITY 2.0
  82
  83 /* Modeling units of ground extent in each X and Z direction. */
  84 #define EDGE 12
  85
  86 static void
  87 makePointList(void)
  88 {
  89   float angle, velocity, direction;
  90   int i;
  91
  92   motion = 1;
  93   for (i=0; i<numPoints; i++) {
  94     pointList[i][0] = 0.0;
  95     pointList[i][1] = 0.0;
  96     pointList[i][2] = 0.0;
  97     pointTime[i] = 0.0;
  98     angle = (RANDOM_RANGE(60.0, 70.0)) * M_PI/180.0;
  99     direction = RANDOM_RANGE(0.0, 360.0) * M_PI/180.0;
 100     pointDirection[i][0] = cos(direction);
 101     pointDirection[i][1] = sin(direction);
 102     velocity = MEAN_VELOCITY + RANDOM_RANGE(-0.8, 1.0);
 103     pointVelocity[i][0] = velocity * cos(angle);
 104     pointVelocity[i][1] = velocity * sin(angle);
 105     colorList[i] = rand() % NUM_COLORS;
 106   }
 107   theTime = 0.0;
 108 }
 109
 110 static void
 111 updatePointList(void)
 112 {
 113   float distance;
 114   int i;
 115
 116   static double t0 = -1.;
 117   double dt, t = glutGet(GLUT_ELAPSED_TIME) / 1000.0;
 118   if (t0 < 0.0)
 119     t0 = t;
 120   dt = t - t0;
 121   t0 = t;
 122
 123   motion = 0;
 124   for (i=0; i<numPoints; i++) {
 125     distance = pointVelocity[i][0] * theTime;
 126
 127     /* X and Z */
 128     pointList[i][0] = pointDirection[i][0] * distance;
 129     pointList[i][2] = pointDirection[i][1] * distance;
 130
 131     /* Z */
 132     pointList[i][1] =
 133       (pointVelocity[i][1] - 0.5 * GRAVITY * pointTime[i])*pointTime[i];
 134
 135     /* If we hit the ground, bounce the point upward again. */
 136     if (pointList[i][1] <= 0.0) {
 137       if (distance > EDGE) {
 138         /* Particle has hit ground past the distance duration of
 139           the particles.  Mark particle as dead. */
 140        colorList[i] = NUM_COLORS;  /* Not moving. */
 141        continue;
 142       }
 143
 144       pointVelocity[i][1] *= 0.8;  /* 80% of previous up velocity. */
 145       pointTime[i] = 0.0;  /* Reset the particles sense of up time. */
 146     }
 147     motion = 1;
 148     pointTime[i] += dt;
 149   }
 150   theTime += dt;
 151   if (!motion && !spin) {
 152     if (repeat) {
 153       makePointList();
 154     } else {
 155       glutIdleFunc(NULL);
 156     }
 157   }
 158 }
 159
 160 static void
 161 idle(void)
 162 {
 163   updatePointList();
 164   if (spin) {
 165     angle += 0.3;
 166     newModel = 1;
 167   }
 168   glutPostRedisplay();
 169 }
 170
 171 static void
 172 visible(int vis)
 173 {
 174   if (vis == GLUT_VISIBLE) {
 175     if (animate && (motion || spin)) {
 176       glutIdleFunc(idle);
 177     }
 178   } else {
 179     glutIdleFunc(NULL);
 180   }
 181 }
 182
 183 static void
 184 recalcModelView(void)
 185 {
 186   glPopMatrix();
 187   glPushMatrix();
 188   glRotatef(angle, 0.0, 1.0, 0.0);
 189   newModel = 0;
 190 }
 191
 192 static void
 193 redraw(void)
 194 {
 195   int i;
 196
 197   glDepthMask(GL_TRUE);
 198   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 199   if (newModel)
 200     recalcModelView();
 201
 202
 203   /* Draw the floor. */
 204 /*  glEnable(GL_TEXTURE_2D);*/
 205   glColor3f(0.5, 1.0, 0.5);
 206   glBegin(GL_QUADS);
 207     glTexCoord2f(0.0, 0.0);
 208     glVertex3f(-EDGE, -0.05, -EDGE);
 209     glTexCoord2f(20.0, 0.0);
 210     glVertex3f(EDGE, -0.05, -EDGE);
 211     glTexCoord2f(20.0, 20.0);
 212     glVertex3f(EDGE, -0.05, EDGE);
 213     glTexCoord2f(0.0, 20.0);
 214     glVertex3f(-EDGE, -0.05, EDGE);
 215   glEnd();
 216
 217   /* Allow particles to blend with each other. */
 218   glDepthMask(GL_FALSE);
 219
 220   if (blend)
 221      glEnable(GL_BLEND);
 222
 223   glDisable(GL_TEXTURE_2D);
 224   glBegin(GL_POINTS);
 225     for (i=0; i<numPoints; i++) {
 226       /* Draw alive particles. */
 227       if (colorList[i] != DEAD) {
 228         glColor4fv(colorSet[colorList[i]]);
 229         glVertex3fv(pointList[i]);
 230       }
 231     }
 232   glEnd();
 233
 234   glDisable(GL_BLEND);
 235
 236   glutSwapBuffers();
 237 }
 238
 239 /* ARGSUSED2 */
 240 static void
 241 mouse(int button, int state, int x, int y)
 242 {
 243   /* Scene can be spun around Y axis using left
 244      mouse button movement. */
 245   if (button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
 246     moving = 1;
 247     begin = x;
 248   }
 249   if (button == GLUT_LEFT_BUTTON && state == GLUT_UP) {
 250     moving = 0;
 251   }
 252 }
 253
 254 /* ARGSUSED1 */
 255 static void
 256 mouseMotion(int x, int y)
 257 {
 258   if (moving) {
 259     angle = angle + (x - begin);
 260     begin = x;
 261     newModel = 1;
 262     glutPostRedisplay();
 263   }
 264 }
 265
 266 static void
 267 menu(int option)
 268 {
 269   switch (option) {
 270   case 0:
 271     makePointList();
 272     break;
 273 #ifdef GL_ARB_point_parameters
 274   case 1:
 275     glPointParameterfvARB(GL_POINT_DISTANCE_ATTENUATION_ARB, constant);
 276     break;
 277   case 2:
 278     glPointParameterfvARB(GL_POINT_DISTANCE_ATTENUATION_ARB, linear);
 279     break;
 280   case 3:
 281     glPointParameterfvARB(GL_POINT_DISTANCE_ATTENUATION_ARB, theQuad);
 282     break;
 283 #endif
 284   case 4:
 285     blend = 1;
 286     break;
 287   case 5:
 288     blend = 0;
 289     break;
 290 #ifdef GL_ARB_point_parameters
 291   case 6:
 292     glPointParameterfARB(GL_POINT_FADE_THRESHOLD_SIZE_ARB, 1.0);
 293     break;
 294   case 7:
 295     glPointParameterfARB(GL_POINT_FADE_THRESHOLD_SIZE_ARB, 10.0);
 296     break;
 297 #endif
 298   case 8:
 299     glEnable(GL_POINT_SMOOTH);
 300     break;
 301   case 9:
 302     glDisable(GL_POINT_SMOOTH);
 303     break;
 304   case 10:
 305     glPointSize(2.0);
 306     break;
 307   case 11:
 308     glPointSize(4.0);
 309     break;
 310   case 12:
 311     glPointSize(8.0);
 312     break;
 313   case 13:
 314     spin = 1 - spin;
 315     if (animate && (spin || motion)) {
 316       glutIdleFunc(idle);
 317     } else {
 318       glutIdleFunc(NULL);
 319     }
 320     break;
 321   case 14:
 322     numPoints = 200;
 323     break;
 324   case 15:
 325     numPoints = 500;
 326     break;
 327   case 16:
 328     numPoints = 1000;
 329     break;
 330   case 17:
 331     numPoints = 2000;
 332     break;
 333   case 666:
 334     exit(0);
 335   }
 336   glutPostRedisplay();
 337 }
 338
 339 /* ARGSUSED1 */
 340 static void
 341 key(unsigned char c, int x, int y)
 342 {
 343   switch (c) {
 344   case 13:
 345     animate = 1 - animate;  /* toggle. */
 346     if (animate && (motion || spin)) {
 347       glutIdleFunc(idle);
 348     } else {
 349       glutIdleFunc(NULL);
 350     }
 351     break;
 352   case ' ':
 353     animate = 1;
 354     makePointList();
 355     glutIdleFunc(idle);
 356     break;
 357   case 27:
 358     exit(0);
 359   }
 360 }
 361
 362 /* Nice floor texture tiling pattern. */
 363 static char *circles[] = {
 364   "....xxxx........",
 365   "..xxxxxxxx......",
 366   ".xxxxxxxxxx.....",
 367   ".xxx....xxx.....",
 368   "xxx......xxx....",
 369   "xxx......xxx....",
 370   "xxx......xxx....",
 371   "xxx......xxx....",
 372   ".xxx....xxx.....",
 373   ".xxxxxxxxxx.....",
 374   "..xxxxxxxx......",
 375   "....xxxx........",
 376   "................",
 377   "................",
 378   "................",
 379   "................",
 380 };
 381
 382 static void
 383 makeFloorTexture(void)
 384 {
 385   GLubyte floorTexture[16][16][3];
 386   GLubyte *loc;
 387   int s, t;
 388
 389   /* Setup RGB image for the texture. */
 390   loc = (GLubyte*) floorTexture;
 391   for (t = 0; t < 16; t++) {
 392     for (s = 0; s < 16; s++) {
 393       if (circles[t][s] == 'x') {
 394         /* Nice blue. */
 395         loc[0] = 0x1f;
 396         loc[1] = 0x1f;
 397         loc[2] = 0x8f;
 398       } else {
 399         /* Light gray. */
 400         loc[0] = 0xca;
 401         loc[1] = 0xca;
 402         loc[2] = 0xca;
 403       }
 404       loc += 3;
 405     }
 406   }
 407
 408   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
 409
 410   if (useMipmaps) {
 411     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
 412       GL_LINEAR_MIPMAP_LINEAR);
 413     gluBuild2DMipmaps(GL_TEXTURE_2D, 3, 16, 16,
 414       GL_RGB, GL_UNSIGNED_BYTE, floorTexture);
 415   } else {
 416     if (linearFiltering) {
 417       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 418     } else {
 419       glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
 420     }
 421     glTexImage2D(GL_TEXTURE_2D, 0, 3, 16, 16, 0,
 422       GL_RGB, GL_UNSIGNED_BYTE, floorTexture);
 423   }
 424 }
 425
 426 int
 427 main(int argc, char **argv)
 428 {
 429   int i;
 430
 431   glutInitWindowSize(300, 300);
 432   glutInit(&argc, argv);
 433   glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH | GLUT_MULTISAMPLE);
 434
 435   for (i=1; i<argc; i++) {
 436     if(!strcmp("-noms", argv[i])) {
 437       glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
 438       printf("forcing no multisampling\n");
 439     } else if(!strcmp("-nomipmaps", argv[i])) {
 440       useMipmaps = 0;
 441     } else if(!strcmp("-nearest", argv[i])) {
 442       linearFiltering = 0;
 443     }
 444   }
 445
 446   glutCreateWindow("point burst");
 447   glewInit();
 448   glutDisplayFunc(redraw);
 449   glutMouseFunc(mouse);
 450   glutMotionFunc(mouseMotion);
 451   glutVisibilityFunc(visible);
 452   glutKeyboardFunc(key);
 453   glutCreateMenu(menu);
 454   glutAddMenuEntry("Reset time", 0);
 455   glutAddMenuEntry("Constant", 1);
 456   glutAddMenuEntry("Linear", 2);
 457   glutAddMenuEntry("Quadratic", 3);
 458   glutAddMenuEntry("Blend on", 4);
 459   glutAddMenuEntry("Blend off", 5);
 460   glutAddMenuEntry("Threshold 1", 6);
 461   glutAddMenuEntry("Threshold 10", 7);
 462   glutAddMenuEntry("Point smooth on", 8);
 463   glutAddMenuEntry("Point smooth off", 9);
 464   glutAddMenuEntry("Point size 2", 10);
 465   glutAddMenuEntry("Point size 4", 11);
 466   glutAddMenuEntry("Point size 8", 12);
 467   glutAddMenuEntry("Toggle spin", 13);
 468   glutAddMenuEntry("200 points ", 14);
 469   glutAddMenuEntry("500 points ", 15);
 470   glutAddMenuEntry("1000 points ", 16);
 471   glutAddMenuEntry("2000 points ", 17);
 472   glutAddMenuEntry("Quit", 666);
 473   glutAttachMenu(GLUT_RIGHT_BUTTON);
 474
 475   if (!glutExtensionSupported("GL_ARB_point_parameters")) {
 476     fprintf(stderr, "Sorry, GL_ARB_point_parameters is not supported.\n");
 477     return -1;
 478   }
 479
 480   glShadeModel(GL_FLAT);
 481   glEnable(GL_DEPTH_TEST);
 482   glEnable(GL_POINT_SMOOTH);
 483   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 484   glPointSize(8.0);
 485 #if GL_ARB_point_parameters
 486   glPointParameterfvARB(GL_POINT_DISTANCE_ATTENUATION_ARB, theQuad);
 487 #endif
 488   glMatrixMode(GL_PROJECTION);
 489   gluPerspective( /* field of view in degree */ 40.0,
 490   /* aspect ratio */ 1.0,
 491     /* Z near */ 0.5, /* Z far */ 40.0);
 492   glMatrixMode(GL_MODELVIEW);
 493   gluLookAt(0.0, 1.0, 8.0, /* eye location */
 494     0.0, 1.0, 0.0,      /* center is at (0,0,0) */
 495     0.0, 1.0, 0.);      /* up is in postivie Y direction */
 496   glPushMatrix();       /* dummy push so we can pop on model
 497                            recalc */
 498
 499   makePointList();
 500   makeFloorTexture();
 501
 502   glutMainLoop();
 503   return 0;             /* ANSI C requires main to return int. */
 504 }