progs/demos/gears.c

   1 /* $Id: gears.c,v 1.6 2000/04/06 02:22:59 brianp Exp $ */
   2
   3 /*
   4  * 3-D gear wheels.  This program is in the public domain.
   5  *
   6  * Command line options:
   7  *    -info      print GL implementation information
   8  *    -exit      automatically exit after 30 seconds
   9  *
  10  *
  11  * Brian Paul
  12  */
  13
  14 /* Conversion to GLUT by Mark J. Kilgard */
  15
  16
  17
  18 #include <math.h>
  19 #include <stdlib.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <GL/glut.h>
  23
  24 #ifndef M_PI
  25 #define M_PI 3.14159265
  26 #endif
  27
  28 static GLint T0 = 0;
  29 static GLint Frames = 0;
  30 static GLint autoexit = 0;
  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 draw(void)
 169 {
 170   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 171
 172   glPushMatrix();
 173     glRotatef(view_rotx, 1.0, 0.0, 0.0);
 174     glRotatef(view_roty, 0.0, 1.0, 0.0);
 175     glRotatef(view_rotz, 0.0, 0.0, 1.0);
 176
 177     glPushMatrix();
 178       glTranslatef(-3.0, -2.0, 0.0);
 179       glRotatef(angle, 0.0, 0.0, 1.0);
 180       glCallList(gear1);
 181     glPopMatrix();
 182
 183     glPushMatrix();
 184       glTranslatef(3.1, -2.0, 0.0);
 185       glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
 186       glCallList(gear2);
 187     glPopMatrix();
 188
 189     glPushMatrix();
 190       glTranslatef(-3.1, 4.2, 0.0);
 191       glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
 192       glCallList(gear3);
 193     glPopMatrix();
 194
 195   glPopMatrix();
 196
 197   glutSwapBuffers();
 198
 199   Frames++;
 200
 201   {
 202      GLint t = glutGet(GLUT_ELAPSED_TIME);
 203      if (t - T0 >= 5000) {
 204         GLfloat seconds = (t - T0) / 1000.0;
 205         GLfloat fps = Frames / seconds;
 206         printf("%d frames in %6.3f seconds = %6.3f FPS\n", Frames, seconds, fps);
 207         T0 = t;
 208         Frames = 0;
 209         if ((t >= 999.0 * autoexit) && (autoexit))
 210            exit(0);
 211      }
 212   }
 213 }
 214
 215
 216 static void
 217 idle(void)
 218 {
 219   angle += 2.0;
 220   glutPostRedisplay();
 221 }
 222
 223 /* change view angle, exit upon ESC */
 224 /* ARGSUSED1 */
 225 static void
 226 key(unsigned char k, int x, int y)
 227 {
 228   switch (k) {
 229   case 'z':
 230     view_rotz += 5.0;
 231     break;
 232   case 'Z':
 233     view_rotz -= 5.0;
 234     break;
 235   case 27:  /* Escape */
 236     exit(0);
 237     break;
 238   default:
 239     return;
 240   }
 241   glutPostRedisplay();
 242 }
 243
 244 /* change view angle */
 245 /* ARGSUSED1 */
 246 static void
 247 special(int k, int x, int y)
 248 {
 249   switch (k) {
 250   case GLUT_KEY_UP:
 251     view_rotx += 5.0;
 252     break;
 253   case GLUT_KEY_DOWN:
 254     view_rotx -= 5.0;
 255     break;
 256   case GLUT_KEY_LEFT:
 257     view_roty += 5.0;
 258     break;
 259   case GLUT_KEY_RIGHT:
 260     view_roty -= 5.0;
 261     break;
 262   default:
 263     return;
 264   }
 265   glutPostRedisplay();
 266 }
 267
 268 /* new window size or exposure */
 269 static void
 270 reshape(int width, int height)
 271 {
 272   GLfloat h = (GLfloat) height / (GLfloat) width;
 273
 274   glViewport(0, 0, (GLint) width, (GLint) height);
 275   glMatrixMode(GL_PROJECTION);
 276   glLoadIdentity();
 277   glFrustum(-1.0, 1.0, -h, h, 5.0, 60.0);
 278   glMatrixMode(GL_MODELVIEW);
 279   glLoadIdentity();
 280   glTranslatef(0.0, 0.0, -40.0);
 281 }
 282
 283 static void
 284 init(int argc, char *argv[])
 285 {
 286   static GLfloat pos[4] = {5.0, 5.0, 10.0, 0.0};
 287   static GLfloat red[4] = {0.8, 0.1, 0.0, 1.0};
 288   static GLfloat green[4] = {0.0, 0.8, 0.2, 1.0};
 289   static GLfloat blue[4] = {0.2, 0.2, 1.0, 1.0};
 290   GLint i;
 291
 292   glLightfv(GL_LIGHT0, GL_POSITION, pos);
 293   glEnable(GL_CULL_FACE);
 294   glEnable(GL_LIGHTING);
 295   glEnable(GL_LIGHT0);
 296   glEnable(GL_DEPTH_TEST);
 297
 298   /* make the gears */
 299   gear1 = glGenLists(1);
 300   glNewList(gear1, GL_COMPILE);
 301   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
 302   gear(1.0, 4.0, 1.0, 20, 0.7);
 303   glEndList();
 304
 305   gear2 = glGenLists(1);
 306   glNewList(gear2, GL_COMPILE);
 307   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
 308   gear(0.5, 2.0, 2.0, 10, 0.7);
 309   glEndList();
 310
 311   gear3 = glGenLists(1);
 312   glNewList(gear3, GL_COMPILE);
 313   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
 314   gear(1.3, 2.0, 0.5, 10, 0.7);
 315   glEndList();
 316
 317   glEnable(GL_NORMALIZE);
 318
 319   for ( i=1; i<argc; i++ ) {
 320     if (strcmp(argv[i], "-info")==0) {
 321       printf("GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
 322       printf("GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
 323       printf("GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
 324       printf("GL_EXTENSIONS = %s\n", (char *) glGetString(GL_EXTENSIONS));
 325     }
 326     else if ( strcmp(argv[i], "-exit")==0) {
 327       autoexit = 30;
 328       printf("Auto Exit after %i seconds.\n", autoexit );
 329     }
 330   }
 331 }
 332
 333 static void
 334 visible(int vis)
 335 {
 336   if (vis == GLUT_VISIBLE)
 337     glutIdleFunc(idle);
 338   else
 339     glutIdleFunc(NULL);
 340 }
 341
 342 int main(int argc, char *argv[])
 343 {
 344   glutInit(&argc, argv);
 345   glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 346
 347   glutInitWindowPosition(0, 0);
 348   glutInitWindowSize(300, 300);
 349   glutCreateWindow("Gears");
 350   init(argc, argv);
 351
 352   glutDisplayFunc(draw);
 353   glutReshapeFunc(reshape);
 354   glutKeyboardFunc(key);
 355   glutSpecialFunc(special);
 356   glutVisibilityFunc(visible);
 357
 358   glutMainLoop();
 359   return 0;             /* ANSI C requires main to return int. */
 360 }