progs/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 <GL/glut.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
  31
  32 /**
  33
  34   Draw a gear wheel.  You'll probably want to call this function when
  35   building a display list since we do a lot of trig here.
  36
  37   Input:  inner_radius - radius of hole at center
  38           outer_radius - radius at center of teeth
  39           width - width of gear
  40           teeth - number of teeth
  41           tooth_depth - depth of tooth
  42
  43  **/
  44
  45 static void
  46 gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
  47   GLint teeth, GLfloat tooth_depth)
  48 {
  49   GLint i;
  50   GLfloat r0, r1, r2;
  51   GLfloat angle, da;
  52   GLfloat u, v, len;
  53
  54   r0 = inner_radius;
  55   r1 = outer_radius - tooth_depth / 2.0;
  56   r2 = outer_radius + tooth_depth / 2.0;
  57
  58   da = 2.0 * M_PI / teeth / 4.0;
  59
  60   glShadeModel(GL_FLAT);
  61
  62   glNormal3f(0.0, 0.0, 1.0);
  63
  64   /* draw front face */
  65   glBegin(GL_QUAD_STRIP);
  66   for (i = 0; i <= teeth; i++) {
  67     angle = i * 2.0 * M_PI / teeth;
  68     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  69     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  70     if (i < teeth) {
  71       glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  72       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  73     }
  74   }
  75   glEnd();
  76
  77   /* draw front sides of teeth */
  78   glBegin(GL_QUADS);
  79   da = 2.0 * M_PI / teeth / 4.0;
  80   for (i = 0; i < teeth; i++) {
  81     angle = i * 2.0 * M_PI / teeth;
  82
  83     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  84     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
  85     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
  86     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  87   }
  88   glEnd();
  89
  90   glNormal3f(0.0, 0.0, -1.0);
  91
  92   /* draw back face */
  93   glBegin(GL_QUAD_STRIP);
  94   for (i = 0; i <= teeth; i++) {
  95     angle = i * 2.0 * M_PI / teeth;
  96     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
  97     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
  98     if (i < teeth) {
  99       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 100       glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 101     }
 102   }
 103   glEnd();
 104
 105   /* draw back sides of teeth */
 106   glBegin(GL_QUADS);
 107   da = 2.0 * M_PI / teeth / 4.0;
 108   for (i = 0; i < teeth; i++) {
 109     angle = i * 2.0 * M_PI / teeth;
 110
 111     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 112     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 113     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 114     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 115   }
 116   glEnd();
 117
 118   /* draw outward faces of teeth */
 119   glBegin(GL_QUAD_STRIP);
 120   for (i = 0; i < teeth; i++) {
 121     angle = i * 2.0 * M_PI / teeth;
 122
 123     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
 124     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 125     u = r2 * cos(angle + da) - r1 * cos(angle);
 126     v = r2 * sin(angle + da) - r1 * sin(angle);
 127     len = sqrt(u * u + v * v);
 128     u /= len;
 129     v /= len;
 130     glNormal3f(v, -u, 0.0);
 131     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
 132     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 133     glNormal3f(cos(angle), sin(angle), 0.0);
 134     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
 135     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 136     u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
 137     v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
 138     glNormal3f(v, -u, 0.0);
 139     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
 140     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 141     glNormal3f(cos(angle), sin(angle), 0.0);
 142   }
 143
 144   glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
 145   glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);
 146
 147   glEnd();
 148
 149   glShadeModel(GL_SMOOTH);
 150
 151   /* draw inside radius cylinder */
 152   glBegin(GL_QUAD_STRIP);
 153   for (i = 0; i <= teeth; i++) {
 154     angle = i * 2.0 * M_PI / teeth;
 155     glNormal3f(-cos(angle), -sin(angle), 0.0);
 156     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 157     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
 158   }
 159   glEnd();
 160
 161 }
 162
 163 static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
 164 static GLint gear1, gear2, gear3;
 165 static GLfloat angle = 0.0;
 166
 167 static void
 168 cleanup(void)
 169 {
 170    glDeleteLists(gear1, 1);
 171    glDeleteLists(gear2, 1);
 172    glDeleteLists(gear3, 1);
 173    glutDestroyWindow(win);
 174 }
 175
 176 static void
 177 draw(void)
 178 {
 179   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 180
 181   glPushMatrix();
 182     glRotatef(view_rotx, 1.0, 0.0, 0.0);
 183     glRotatef(view_roty, 0.0, 1.0, 0.0);
 184     glRotatef(view_rotz, 0.0, 0.0, 1.0);
 185
 186     glPushMatrix();
 187       glTranslatef(-3.0, -2.0, 0.0);
 188       glRotatef(angle, 0.0, 0.0, 1.0);
 189       glCallList(gear1);
 190     glPopMatrix();
 191
 192     glPushMatrix();
 193       glTranslatef(3.1, -2.0, 0.0);
 194       glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
 195       glCallList(gear2);
 196     glPopMatrix();
 197
 198     glPushMatrix();
 199       glTranslatef(-3.1, 4.2, 0.0);
 200       glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
 201       glCallList(gear3);
 202     glPopMatrix();
 203
 204   glPopMatrix();
 205
 206   glutSwapBuffers();
 207
 208   Frames++;
 209
 210   {
 211     GLint t = glutGet(GLUT_ELAPSED_TIME);
 212     if (t - T0 >= 5000) {
 213       GLfloat seconds = (t - T0) / 1000.0;
 214       GLfloat fps = Frames / seconds;
 215       printf("%d frames in %6.3f seconds = %6.3f FPS\n", Frames, seconds, fps);
 216       T0 = t;
 217       Frames = 0;
 218       if ((t >= 999.0 * autoexit) && (autoexit)) {
 219         cleanup();
 220         exit(0);
 221       }
 222     }
 223   }
 224 }
 225
 226
 227 static void
 228 idle(void)
 229 {
 230   static double t0 = -1.;
 231   double dt, t = glutGet(GLUT_ELAPSED_TIME) / 1000.0;
 232   if (t0 < 0.0)
 233     t0 = t;
 234   dt = t - t0;
 235   t0 = t;
 236
 237   angle += 70.0 * dt;  /* 70 degrees per second */
 238   angle = fmod(angle, 360.0); /* prevents eventual overflow */
 239
 240   glutPostRedisplay();
 241 }
 242
 243 /* change view angle, exit upon ESC */
 244 /* ARGSUSED1 */
 245 static void
 246 key(unsigned char k, int x, int y)
 247 {
 248   switch (k) {
 249   case 'z':
 250     view_rotz += 5.0;
 251     break;
 252   case 'Z':
 253     view_rotz -= 5.0;
 254     break;
 255   case 27:  /* Escape */
 256     cleanup();
 257     exit(0);
 258     break;
 259   default:
 260     return;
 261   }
 262   glutPostRedisplay();
 263 }
 264
 265 /* change view angle */
 266 /* ARGSUSED1 */
 267 static void
 268 special(int k, int x, int y)
 269 {
 270   switch (k) {
 271   case GLUT_KEY_UP:
 272     view_rotx += 5.0;
 273     break;
 274   case GLUT_KEY_DOWN:
 275     view_rotx -= 5.0;
 276     break;
 277   case GLUT_KEY_LEFT:
 278     view_roty += 5.0;
 279     break;
 280   case GLUT_KEY_RIGHT:
 281     view_roty -= 5.0;
 282     break;
 283   default:
 284     return;
 285   }
 286   glutPostRedisplay();
 287 }
 288
 289 /* new window size or exposure */
 290 static void
 291 reshape(int width, int height)
 292 {
 293   GLfloat h = (GLfloat) height / (GLfloat) width;
 294
 295   glViewport(0, 0, (GLint) width, (GLint) height);
 296   glMatrixMode(GL_PROJECTION);
 297   glLoadIdentity();
 298   glFrustum(-1.0, 1.0, -h, h, 5.0, 60.0);
 299   glMatrixMode(GL_MODELVIEW);
 300   glLoadIdentity();
 301   glTranslatef(0.0, 0.0, -40.0);
 302 }
 303
 304 static void
 305 init(int argc, char *argv[])
 306 {
 307   static GLfloat pos[4] = {5.0, 5.0, 10.0, 0.0};
 308   static GLfloat red[4] = {0.8, 0.1, 0.0, 1.0};
 309   static GLfloat green[4] = {0.0, 0.8, 0.2, 1.0};
 310   static GLfloat blue[4] = {0.2, 0.2, 1.0, 1.0};
 311   GLint i;
 312
 313   glLightfv(GL_LIGHT0, GL_POSITION, pos);
 314   glEnable(GL_CULL_FACE);
 315   glEnable(GL_LIGHTING);
 316   glEnable(GL_LIGHT0);
 317   glEnable(GL_DEPTH_TEST);
 318
 319   /* make the gears */
 320   gear1 = glGenLists(1);
 321   glNewList(gear1, GL_COMPILE);
 322   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
 323   gear(1.0, 4.0, 1.0, 20, 0.7);
 324   glEndList();
 325
 326   gear2 = glGenLists(1);
 327   glNewList(gear2, GL_COMPILE);
 328   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
 329   gear(0.5, 2.0, 2.0, 10, 0.7);
 330   glEndList();
 331
 332   gear3 = glGenLists(1);
 333   glNewList(gear3, GL_COMPILE);
 334   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
 335   gear(1.3, 2.0, 0.5, 10, 0.7);
 336   glEndList();
 337
 338   glEnable(GL_NORMALIZE);
 339
 340   for ( i=1; i<argc; i++ ) {
 341     if (strcmp(argv[i], "-info")==0) {
 342       printf("GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
 343       printf("GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
 344       printf("GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
 345       printf("GL_EXTENSIONS = %s\n", (char *) glGetString(GL_EXTENSIONS));
 346     }
 347     else if ( strcmp(argv[i], "-exit")==0) {
 348       autoexit = 30;
 349       printf("Auto Exit after %i seconds.\n", autoexit );
 350     }
 351   }
 352 }
 353
 354 static void
 355 visible(int vis)
 356 {
 357   if (vis == GLUT_VISIBLE)
 358     glutIdleFunc(idle);
 359   else
 360     glutIdleFunc(NULL);
 361 }
 362
 363 int main(int argc, char *argv[])
 364 {
 365   glutInit(&argc, argv);
 366   glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 367
 368   glutInitWindowPosition(0, 0);
 369   glutInitWindowSize(300, 300);
 370   win = glutCreateWindow("Gears");
 371   init(argc, argv);
 372
 373   glutDisplayFunc(draw);
 374   glutReshapeFunc(reshape);
 375   glutKeyboardFunc(key);
 376   glutSpecialFunc(special);
 377   glutVisibilityFunc(visible);
 378
 379   glutMainLoop();
 380   return 0;             /* ANSI C requires main to return int. */
 381 }