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
26static GLint T0 = 0;
27static GLint Frames = 0;
28static GLint autoexit = 0;
29static GLint win = 0;
30static GLboolean Visible = GL_TRUE;
31static GLboolean Animate = GL_TRUE;
32static 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
48static void
49gear(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
166static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
167static GLint gear1, gear2, gear3;
168static GLfloat angle = 0.0;
169
170static void
171cleanup(void)
172{
173   glDeleteLists(gear1, 1);
174   glDeleteLists(gear2, 1);
175   glDeleteLists(gear3, 1);
176   glutDestroyWindow(win);
177}
178
179static void
180draw(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
234static void
235idle(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
250static void
251update_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 */
261static void
262key(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 */
293static void
294special(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 */
316static void
317reshape(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
328static void
329init(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  glClearColor(1.0, 1.0, 1.0, 0.0);
378}
379
380
381static void
382visible(int vis)
383{
384   Visible = vis;
385   update_idle_func();
386}
387
388int main(int argc, char *argv[])
389{
390  glutInit(&argc, argv);
391  glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
392
393  glutInitWindowPosition(0, 0);
394  glutInitWindowSize(300, 300);
395  win = glutCreateWindow("Gears");
396  init(argc, argv);
397
398  glutDisplayFunc(draw);
399  glutReshapeFunc(reshape);
400  glutKeyboardFunc(key);
401  glutSpecialFunc(special);
402  glutVisibilityFunc(visible);
403  update_idle_func();
404
405  glutMainLoop();
406  return 0;             /* ANSI C requires main to return int. */
407}
408