progs/demos/gears.c

   1 /* $Id: gears.c,v 1.1 1999/08/19 00:55:40 jtg Exp $ */
   2
   3 /*
   4  * 3-D gear wheels.  This program is in the public domain.
   5  *
   6  * Brian Paul
   7  */
   8
   9 /* Conversion to GLUT by Mark J. Kilgard */
  10
  11 /*
  12  * $Log: gears.c,v $
  13  * Revision 1.1  1999/08/19 00:55:40  jtg
  14  * Initial revision
  15  *
  16  * Revision 3.2  1999/06/03 17:07:36  brianp
  17  * an extra quad was being drawn in front and back faces
  18  *
  19  * Revision 3.1  1998/11/03 02:49:10  brianp
  20  * added fps output
  21  *
  22  * Revision 3.0  1998/02/14 18:42:29  brianp
  23  * initial rev
  24  *
  25  */
  26
  27
  28 #include <math.h>
  29 #include <stdlib.h>
  30 #include <stdio.h>
  31 #include <GL/glut.h>
  32
  33 #ifndef M_PI
  34 #define M_PI 3.14159265
  35 #endif
  36
  37 static GLint T0 = 0;
  38 static GLint Frames = 0;
  39
  40
  41 /**
  42
  43   Draw a gear wheel.  You'll probably want to call this function when
  44   building a display list since we do a lot of trig here.
  45
  46   Input:  inner_radius - radius of hole at center
  47           outer_radius - radius at center of teeth
  48           width - width of gear
  49           teeth - number of teeth
  50           tooth_depth - depth of tooth
  51
  52  **/
  53
  54 static void
  55 gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
  56   GLint teeth, GLfloat tooth_depth)
  57 {
  58   GLint i;
  59   GLfloat r0, r1, r2;
  60   GLfloat angle, da;
  61   GLfloat u, v, len;
  62
  63   r0 = inner_radius;
  64   r1 = outer_radius - tooth_depth / 2.0;
  65   r2 = outer_radius + tooth_depth / 2.0;
  66
  67   da = 2.0 * M_PI / teeth / 4.0;
  68
  69   glShadeModel(GL_FLAT);
  70
  71   glNormal3f(0.0, 0.0, 1.0);
  72
  73   /* draw front face */
  74   glBegin(GL_QUAD_STRIP);
  75   for (i = 0; i <= teeth; i++) {
  76     angle = i * 2.0 * M_PI / teeth;
  77     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  78     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  79     if (i < teeth) {
  80       glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  81       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  82     }
  83   }
  84   glEnd();
  85
  86   /* draw front sides of teeth */
  87   glBegin(GL_QUADS);
  88   da = 2.0 * M_PI / teeth / 4.0;
  89   for (i = 0; i < teeth; i++) {
  90     angle = i * 2.0 * M_PI / teeth;
  91
  92     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  93     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
  94     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
  95     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  96   }
  97   glEnd();
  98
  99   glNormal3f(0.0, 0.0, -1.0);
 100
 101   /* draw back face */
 102   glBegin(GL_QUAD_STRIP);
 103   for (i = 0; i <= teeth; i++) {
 104     angle = i * 2.0 * M_PI / teeth;
 105     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 106     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 107     if (i < teeth) {
 108       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 109       glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 110     }
 111   }
 112   glEnd();
 113
 114   /* draw back sides of teeth */
 115   glBegin(GL_QUADS);
 116   da = 2.0 * M_PI / teeth / 4.0;
 117   for (i = 0; i < teeth; i++) {
 118     angle = i * 2.0 * M_PI / teeth;
 119
 120     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 121     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 122     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 123     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 124   }
 125   glEnd();
 126
 127   /* draw outward faces of teeth */
 128   glBegin(GL_QUAD_STRIP);
 129   for (i = 0; i < teeth; i++) {
 130     angle = i * 2.0 * M_PI / teeth;
 131
 132     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
 133     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 134     u = r2 * cos(angle + da) - r1 * cos(angle);
 135     v = r2 * sin(angle + da) - r1 * sin(angle);
 136     len = sqrt(u * u + v * v);
 137     u /= len;
 138     v /= len;
 139     glNormal3f(v, -u, 0.0);
 140     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
 141     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 142     glNormal3f(cos(angle), sin(angle), 0.0);
 143     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
 144     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 145     u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
 146     v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
 147     glNormal3f(v, -u, 0.0);
 148     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
 149     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 150     glNormal3f(cos(angle), sin(angle), 0.0);
 151   }
 152
 153   glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
 154   glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);
 155
 156   glEnd();
 157
 158   glShadeModel(GL_SMOOTH);
 159
 160   /* draw inside radius cylinder */
 161   glBegin(GL_QUAD_STRIP);
 162   for (i = 0; i <= teeth; i++) {
 163     angle = i * 2.0 * M_PI / teeth;
 164     glNormal3f(-cos(angle), -sin(angle), 0.0);
 165     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 166     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
 167   }
 168   glEnd();
 169
 170 }
 171
 172 static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
 173 static GLint gear1, gear2, gear3;
 174 static GLfloat angle = 0.0;
 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      GLint t = glutGet(GLUT_ELAPSED_TIME);
 211      if (t - T0 >= 5000) {
 212         GLfloat seconds = (t - T0) / 1000.0;
 213         GLfloat fps = Frames / seconds;
 214         printf("%d frames in %g seconds = %g FPS\n", Frames, seconds, fps);
 215         T0 = t;
 216         Frames = 0;
 217      }
 218   }
 219 }
 220
 221
 222 static void
 223 idle(void)
 224 {
 225   angle += 2.0;
 226   glutPostRedisplay();
 227 }
 228
 229 /* change view angle, exit upon ESC */
 230 /* ARGSUSED1 */
 231 static void
 232 key(unsigned char k, int x, int y)
 233 {
 234   switch (k) {
 235   case 'z':
 236     view_rotz += 5.0;
 237     break;
 238   case 'Z':
 239     view_rotz -= 5.0;
 240     break;
 241   case 27:  /* Escape */
 242     exit(0);
 243     break;
 244   default:
 245     return;
 246   }
 247   glutPostRedisplay();
 248 }
 249
 250 /* change view angle */
 251 /* ARGSUSED1 */
 252 static void
 253 special(int k, int x, int y)
 254 {
 255   switch (k) {
 256   case GLUT_KEY_UP:
 257     view_rotx += 5.0;
 258     break;
 259   case GLUT_KEY_DOWN:
 260     view_rotx -= 5.0;
 261     break;
 262   case GLUT_KEY_LEFT:
 263     view_roty += 5.0;
 264     break;
 265   case GLUT_KEY_RIGHT:
 266     view_roty -= 5.0;
 267     break;
 268   default:
 269     return;
 270   }
 271   glutPostRedisplay();
 272 }
 273
 274 /* new window size or exposure */
 275 static void
 276 reshape(int width, int height)
 277 {
 278   GLfloat h = (GLfloat) height / (GLfloat) width;
 279
 280   glViewport(0, 0, (GLint) width, (GLint) height);
 281   glMatrixMode(GL_PROJECTION);
 282   glLoadIdentity();
 283   glFrustum(-1.0, 1.0, -h, h, 5.0, 60.0);
 284   glMatrixMode(GL_MODELVIEW);
 285   glLoadIdentity();
 286   glTranslatef(0.0, 0.0, -40.0);
 287 }
 288
 289 static void
 290 init(void)
 291 {
 292   static GLfloat pos[4] =
 293   {5.0, 5.0, 10.0, 0.0};
 294   static GLfloat red[4] =
 295   {0.8, 0.1, 0.0, 1.0};
 296   static GLfloat green[4] =
 297   {0.0, 0.8, 0.2, 1.0};
 298   static GLfloat blue[4] =
 299   {0.2, 0.2, 1.0, 1.0};
 300
 301   glLightfv(GL_LIGHT0, GL_POSITION, pos);
 302   glEnable(GL_CULL_FACE);
 303   glEnable(GL_LIGHTING);
 304   glEnable(GL_LIGHT0);
 305   glEnable(GL_DEPTH_TEST);
 306
 307   /* make the gears */
 308   gear1 = glGenLists(1);
 309   glNewList(gear1, GL_COMPILE);
 310   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
 311   gear(1.0, 4.0, 1.0, 20, 0.7);
 312   glEndList();
 313
 314   gear2 = glGenLists(1);
 315   glNewList(gear2, GL_COMPILE);
 316   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
 317   gear(0.5, 2.0, 2.0, 10, 0.7);
 318   glEndList();
 319
 320   gear3 = glGenLists(1);
 321   glNewList(gear3, GL_COMPILE);
 322   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
 323   gear(1.3, 2.0, 0.5, 10, 0.7);
 324   glEndList();
 325
 326   glEnable(GL_NORMALIZE);
 327 }
 328
 329 void
 330 visible(int vis)
 331 {
 332   if (vis == GLUT_VISIBLE)
 333     glutIdleFunc(idle);
 334   else
 335     glutIdleFunc(NULL);
 336 }
 337
 338 int main(int argc, char *argv[])
 339 {
 340   glutInit(&argc, argv);
 341   glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 342
 343   glutInitWindowPosition(0, 0);
 344   glutInitWindowSize(300, 300);
 345   glutCreateWindow("Gears");
 346   init();
 347
 348   glutDisplayFunc(draw);
 349   glutReshapeFunc(reshape);
 350   glutKeyboardFunc(key);
 351   glutSpecialFunc(special);
 352   glutVisibilityFunc(visible);
 353
 354   glutMainLoop();
 355   return 0;             /* ANSI C requires main to return int. */
 356 }