src/demos/gears.c

   1 /*
   2  * 3-D gear wheels.  This program is in the public domain.
   3  *
   4  * Command line options:
   5  *    -info      print GL implementation information
   6  *    -exit      automatically exit after 30 seconds
   7  *
   8  *
   9  * Brian Paul
  10  */
  11
  12 /* Conversion to GLUT by Mark J. Kilgard */
  13
  14
  15
  16 #include <math.h>
  17 #include <stdlib.h>
  18 #include <stdio.h>
  19 #include <string.h>
  20 #include "glut_wrap.h"
  21
  22 #ifndef M_PI
  23 #define M_PI 3.14159265
  24 #endif
  25
  26 static GLint T0 = 0;
  27 static GLint Frames = 0;
  28 static GLint autoexit = 0;
  29 static GLint win = 0;
  30 static GLboolean Visible = GL_TRUE;
  31 static GLboolean Animate = GL_TRUE;
  32 static GLfloat viewDist = 40.0;
  33
  34
  35 /**
  36
  37   Draw a gear wheel.  You'll probably want to call this function when
  38   building a display list since we do a lot of trig here.
  39
  40   Input:  inner_radius - radius of hole at center
  41           outer_radius - radius at center of teeth
  42           width - width of gear
  43           teeth - number of teeth
  44           tooth_depth - depth of tooth
  45
  46  **/
  47
  48 static void
  49 gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
  50   GLint teeth, GLfloat tooth_depth)
  51 {
  52   GLint i;
  53   GLfloat r0, r1, r2;
  54   GLfloat angle, da;
  55   GLfloat u, v, len;
  56
  57   r0 = inner_radius;
  58   r1 = outer_radius - tooth_depth / 2.0;
  59   r2 = outer_radius + tooth_depth / 2.0;
  60
  61   da = 2.0 * M_PI / teeth / 4.0;
  62
  63   glShadeModel(GL_FLAT);
  64
  65   glNormal3f(0.0, 0.0, 1.0);
  66
  67   /* draw front face */
  68   glBegin(GL_QUAD_STRIP);
  69   for (i = 0; i <= teeth; i++) {
  70     angle = i * 2.0 * M_PI / teeth;
  71     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  72     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  73     if (i < teeth) {
  74       glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  75       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  76     }
  77   }
  78   glEnd();
  79
  80   /* draw front sides of teeth */
  81   glBegin(GL_QUADS);
  82   da = 2.0 * M_PI / teeth / 4.0;
  83   for (i = 0; i < teeth; i++) {
  84     angle = i * 2.0 * M_PI / teeth;
  85
  86     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  87     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
  88     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
  89     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  90   }
  91   glEnd();
  92
  93   glNormal3f(0.0, 0.0, -1.0);
  94
  95   /* draw back face */
  96   glBegin(GL_QUAD_STRIP);
  97   for (i = 0; i <= teeth; i++) {
  98     angle = i * 2.0 * M_PI / teeth;
  99     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 100     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 101     if (i < teeth) {
 102       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 103       glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 104     }
 105   }
 106   glEnd();
 107
 108   /* draw back sides of teeth */
 109   glBegin(GL_QUADS);
 110   da = 2.0 * M_PI / teeth / 4.0;
 111   for (i = 0; i < teeth; i++) {
 112     angle = i * 2.0 * M_PI / teeth;
 113
 114     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 115     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 116     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 117     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 118   }
 119   glEnd();
 120
 121   /* draw outward faces of teeth */
 122   glBegin(GL_QUAD_STRIP);
 123   for (i = 0; i < teeth; i++) {
 124     angle = i * 2.0 * M_PI / teeth;
 125
 126     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
 127     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 128     u = r2 * cos(angle + da) - r1 * cos(angle);
 129     v = r2 * sin(angle + da) - r1 * sin(angle);
 130     len = sqrt(u * u + v * v);
 131     u /= len;
 132     v /= len;
 133     glNormal3f(v, -u, 0.0);
 134     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
 135     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 136     glNormal3f(cos(angle), sin(angle), 0.0);
 137     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
 138     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 139     u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
 140     v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
 141     glNormal3f(v, -u, 0.0);
 142     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
 143     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 144     glNormal3f(cos(angle), sin(angle), 0.0);
 145   }
 146
 147   glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
 148   glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);
 149
 150   glEnd();
 151
 152   glShadeModel(GL_SMOOTH);
 153
 154   /* draw inside radius cylinder */
 155   glBegin(GL_QUAD_STRIP);
 156   for (i = 0; i <= teeth; i++) {
 157     angle = i * 2.0 * M_PI / teeth;
 158     glNormal3f(-cos(angle), -sin(angle), 0.0);
 159     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 160     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
 161   }
 162   glEnd();
 163
 164 }
 165
 166 static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
 167 static GLint gear1, gear2, gear3;
 168 static GLfloat angle = 0.0;
 169
 170 static void
 171 cleanup(void)
 172 {
 173    glDeleteLists(gear1, 1);
 174    glDeleteLists(gear2, 1);
 175    glDeleteLists(gear3, 1);
 176    glutDestroyWindow(win);
 177 }
 178
 179 static void
 180 draw(void)
 181 {
 182   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 183
 184   glPushMatrix();
 185
 186     glTranslatef(0.0, 0.0, -viewDist);
 187
 188     glRotatef(view_rotx, 1.0, 0.0, 0.0);
 189     glRotatef(view_roty, 0.0, 1.0, 0.0);
 190     glRotatef(view_rotz, 0.0, 0.0, 1.0);
 191
 192     glPushMatrix();
 193       glTranslatef(-3.0, -2.0, 0.0);
 194       glRotatef(angle, 0.0, 0.0, 1.0);
 195       glCallList(gear1);
 196     glPopMatrix();
 197
 198     glPushMatrix();
 199       glTranslatef(3.1, -2.0, 0.0);
 200       glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
 201       glCallList(gear2);
 202     glPopMatrix();
 203
 204     glPushMatrix();
 205       glTranslatef(-3.1, 4.2, 0.0);
 206       glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
 207       glCallList(gear3);
 208     glPopMatrix();
 209
 210   glPopMatrix();
 211
 212   glutSwapBuffers();
 213
 214   Frames++;
 215
 216   {
 217     GLint t = glutGet(GLUT_ELAPSED_TIME);
 218     if (t - T0 >= 5000) {
 219       GLfloat seconds = (t - T0) / 1000.0;
 220       GLfloat fps = Frames / seconds;
 221       printf("%d frames in %6.3f seconds = %6.3f FPS\n", Frames, seconds, fps);
 222       fflush(stdout);
 223       T0 = t;
 224       Frames = 0;
 225       if ((t >= 999.0 * autoexit) && (autoexit)) {
 226         cleanup();
 227         exit(0);
 228       }
 229     }
 230   }
 231 }
 232
 233
 234 static void
 235 idle(void)
 236 {
 237   static double t0 = -1.;
 238   double dt, t = glutGet(GLUT_ELAPSED_TIME) / 1000.0;
 239   if (t0 < 0.0)
 240     t0 = t;
 241   dt = t - t0;
 242   t0 = t;
 243
 244   angle += 70.0 * dt;  /* 70 degrees per second */
 245   angle = fmod(angle, 360.0); /* prevents eventual overflow */
 246
 247   glutPostRedisplay();
 248 }
 249
 250 static void
 251 update_idle_func(void)
 252 {
 253   if (Visible && Animate)
 254     glutIdleFunc(idle);
 255   else
 256     glutIdleFunc(NULL);
 257 }
 258
 259 /* change view angle, exit upon ESC */
 260 /* ARGSUSED1 */
 261 static void
 262 key(unsigned char k, int x, int y)
 263 {
 264   switch (k) {
 265   case 'z':
 266     view_rotz += 5.0;
 267     break;
 268   case 'Z':
 269     view_rotz -= 5.0;
 270     break;
 271   case 'd':
 272      viewDist += 1.0;
 273      break;
 274   case 'D':
 275      viewDist -= 1.0;
 276      break;
 277   case 'a':
 278      Animate = !Animate;
 279      update_idle_func();
 280      break;
 281   case 27:  /* Escape */
 282     cleanup();
 283     exit(0);
 284     break;
 285   default:
 286     return;
 287   }
 288   glutPostRedisplay();
 289 }
 290
 291 /* change view angle */
 292 /* ARGSUSED1 */
 293 static void
 294 special(int k, int x, int y)
 295 {
 296   switch (k) {
 297   case GLUT_KEY_UP:
 298     view_rotx += 5.0;
 299     break;
 300   case GLUT_KEY_DOWN:
 301     view_rotx -= 5.0;
 302     break;
 303   case GLUT_KEY_LEFT:
 304     view_roty += 5.0;
 305     break;
 306   case GLUT_KEY_RIGHT:
 307     view_roty -= 5.0;
 308     break;
 309   default:
 310     return;
 311   }
 312   glutPostRedisplay();
 313 }
 314
 315 /* new window size or exposure */
 316 static void
 317 reshape(int width, int height)
 318 {
 319   GLfloat h = (GLfloat) height / (GLfloat) width;
 320
 321   glViewport(0, 0, (GLint) width, (GLint) height);
 322   glMatrixMode(GL_PROJECTION);
 323   glLoadIdentity();
 324   glFrustum(-1.0, 1.0, -h, h, 5.0, 200.0);
 325   glMatrixMode(GL_MODELVIEW);
 326 }
 327
 328 static void
 329 init(int argc, char *argv[])
 330 {
 331   static GLfloat pos[4] = {5.0, 5.0, 10.0, 0.0};
 332   static GLfloat red[4] = {0.8, 0.1, 0.0, 1.0};
 333   static GLfloat green[4] = {0.0, 0.8, 0.2, 1.0};
 334   static GLfloat blue[4] = {0.2, 0.2, 1.0, 1.0};
 335   GLint i;
 336
 337   glLightfv(GL_LIGHT0, GL_POSITION, pos);
 338   glEnable(GL_CULL_FACE);
 339   glEnable(GL_LIGHTING);
 340   glEnable(GL_LIGHT0);
 341   glEnable(GL_DEPTH_TEST);
 342
 343   /* make the gears */
 344   gear1 = glGenLists(1);
 345   glNewList(gear1, GL_COMPILE);
 346   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
 347   gear(1.0, 4.0, 1.0, 20, 0.7);
 348   glEndList();
 349
 350   gear2 = glGenLists(1);
 351   glNewList(gear2, GL_COMPILE);
 352   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
 353   gear(0.5, 2.0, 2.0, 10, 0.7);
 354   glEndList();
 355
 356   gear3 = glGenLists(1);
 357   glNewList(gear3, GL_COMPILE);
 358   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
 359   gear(1.3, 2.0, 0.5, 10, 0.7);
 360   glEndList();
 361
 362   glEnable(GL_NORMALIZE);
 363
 364   for ( i=1; i<argc; i++ ) {
 365     if (strcmp(argv[i], "-info")==0) {
 366       printf("GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
 367       printf("GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
 368       printf("GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
 369       printf("GL_EXTENSIONS = %s\n", (char *) glGetString(GL_EXTENSIONS));
 370     }
 371     else if ( strcmp(argv[i], "-exit")==0) {
 372       autoexit = 30;
 373       printf("Auto Exit after %i seconds.\n", autoexit );
 374     }
 375   }
 376 }
 377
 378
 379 static void
 380 visible(int vis)
 381 {
 382    Visible = vis;
 383    update_idle_func();
 384 }
 385
 386 int main(int argc, char *argv[])
 387 {
 388   glutInitWindowSize(300, 300);
 389   glutInit(&argc, argv);
 390   glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 391   win = glutCreateWindow("Gears");
 392   init(argc, argv);
 393
 394   glutDisplayFunc(draw);
 395   glutReshapeFunc(reshape);
 396   glutKeyboardFunc(key);
 397   glutSpecialFunc(special);
 398   glutVisibilityFunc(visible);
 399   update_idle_func();
 400
 401   glutMainLoop();
 402   return 0;             /* ANSI C requires main to return int. */
 403 }