progs/ggi/gears.c

   1 /* $Id: gears.c,v 1.1 1999/08/21 06:27:37 jtaylor 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  1999/08/21 06:27:37  jtaylor
  14  * *** empty log message ***
  15  *
  16  * Revision 1.5  1999/07/31 21:51:09  jtaylor
  17  * *** empty log message ***
  18  *
  19  * Revision 3.2  1999/06/03 17:07:36  brianp
  20  * an extra quad was being drawn in front and back faces
  21  *
  22  * Revision 3.1  1998/11/03 02:49:10  brianp
  23  * added fps output
  24  *
  25  * Revision 3.0  1998/02/14 18:42:29  brianp
  26  * initial rev
  27  *
  28  */
  29
  30
  31 #include <math.h>
  32 #include <stdlib.h>
  33 #include <stdio.h>
  34 #include <GL/glut.h>
  35
  36 #ifndef M_PI
  37 #define M_PI 3.14159265
  38 #endif
  39
  40 static GLint T0 = 0;
  41 static GLint Frames = 0;
  42
  43
  44 /**
  45
  46   Draw a gear wheel.  You'll probably want to call this function when
  47   building a display list since we do a lot of trig here.
  48
  49   Input:  inner_radius - radius of hole at center
  50           outer_radius - radius at center of teeth
  51           width - width of gear
  52           teeth - number of teeth
  53           tooth_depth - depth of tooth
  54
  55  **/
  56
  57 static void
  58 gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
  59   GLint teeth, GLfloat tooth_depth)
  60 {
  61   GLint i;
  62   GLfloat r0, r1, r2;
  63   GLfloat angle, da;
  64   GLfloat u, v, len;
  65
  66   r0 = inner_radius;
  67   r1 = outer_radius - tooth_depth / 2.0;
  68   r2 = outer_radius + tooth_depth / 2.0;
  69
  70   da = 2.0 * M_PI / teeth / 4.0;
  71
  72   glShadeModel(GL_FLAT);
  73
  74   glNormal3f(0.0, 0.0, 1.0);
  75
  76   /* draw front face */
  77   glBegin(GL_QUAD_STRIP);
  78   for (i = 0; i <= teeth; i++) {
  79     angle = i * 2.0 * M_PI / teeth;
  80     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  81     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  82     if (i < teeth) {
  83       glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  84       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  85     }
  86   }
  87   glEnd();
  88
  89   /* draw front sides of teeth */
  90   glBegin(GL_QUADS);
  91   da = 2.0 * M_PI / teeth / 4.0;
  92   for (i = 0; i < teeth; i++) {
  93     angle = i * 2.0 * M_PI / teeth;
  94
  95     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  96     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
  97     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
  98     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  99   }
 100   glEnd();
 101
 102   glNormal3f(0.0, 0.0, -1.0);
 103
 104   /* draw back face */
 105   glBegin(GL_QUAD_STRIP);
 106   for (i = 0; i <= teeth; i++) {
 107     angle = i * 2.0 * M_PI / teeth;
 108     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 109     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 110     if (i < teeth) {
 111       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 112       glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 113     }
 114   }
 115   glEnd();
 116
 117   /* draw back sides of teeth */
 118   glBegin(GL_QUADS);
 119   da = 2.0 * M_PI / teeth / 4.0;
 120   for (i = 0; i < teeth; i++) {
 121     angle = i * 2.0 * M_PI / teeth;
 122
 123     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 124     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 125     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 126     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 127   }
 128   glEnd();
 129
 130   /* draw outward faces of teeth */
 131   glBegin(GL_QUAD_STRIP);
 132   for (i = 0; i < teeth; i++) {
 133     angle = i * 2.0 * M_PI / teeth;
 134
 135     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
 136     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 137     u = r2 * cos(angle + da) - r1 * cos(angle);
 138     v = r2 * sin(angle + da) - r1 * sin(angle);
 139     len = sqrt(u * u + v * v);
 140     u /= len;
 141     v /= len;
 142     glNormal3f(v, -u, 0.0);
 143     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
 144     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 145     glNormal3f(cos(angle), sin(angle), 0.0);
 146     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
 147     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 148     u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
 149     v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
 150     glNormal3f(v, -u, 0.0);
 151     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
 152     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 153     glNormal3f(cos(angle), sin(angle), 0.0);
 154   }
 155
 156   glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
 157   glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);
 158
 159   glEnd();
 160
 161   glShadeModel(GL_SMOOTH);
 162
 163   /* draw inside radius cylinder */
 164   glBegin(GL_QUAD_STRIP);
 165   for (i = 0; i <= teeth; i++) {
 166     angle = i * 2.0 * M_PI / teeth;
 167     glNormal3f(-cos(angle), -sin(angle), 0.0);
 168     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 169     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
 170   }
 171   glEnd();
 172
 173 }
 174
 175 static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
 176 static GLint gear1, gear2, gear3;
 177 static GLfloat angle = 0.0;
 178
 179 static void
 180 draw(void)
 181 {
 182   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 183
 184   glPushMatrix();
 185   glRotatef(view_rotx, 1.0, 0.0, 0.0);
 186   glRotatef(view_roty, 0.0, 1.0, 0.0);
 187   glRotatef(view_rotz, 0.0, 0.0, 1.0);
 188
 189   glPushMatrix();
 190   glTranslatef(-3.0, -2.0, 0.0);
 191   glRotatef(angle, 0.0, 0.0, 1.0);
 192   glCallList(gear1);
 193   glPopMatrix();
 194
 195   glPushMatrix();
 196   glTranslatef(3.1, -2.0, 0.0);
 197   glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
 198   glCallList(gear2);
 199   glPopMatrix();
 200
 201   glPushMatrix();
 202   glTranslatef(-3.1, 4.2, 0.0);
 203   glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
 204   glCallList(gear3);
 205   glPopMatrix();
 206
 207   glPopMatrix();
 208
 209   glutSwapBuffers();
 210
 211   Frames++;
 212   {
 213      GLint t = glutGet(GLUT_ELAPSED_TIME);
 214      if (t - T0 >= 5000) {
 215         GLfloat seconds = (t - T0) / 1000.0;
 216         GLfloat fps = Frames / seconds;
 217         printf("%d frames in %g seconds = %g FPS\n", Frames, seconds, fps);
 218         T0 = t;
 219         Frames = 0;
 220      }
 221   }
 222 }
 223
 224
 225 static void
 226 idle(void)
 227 {
 228   angle += 2.0;
 229   glutPostRedisplay();
 230 }
 231
 232 /* change view angle, exit upon ESC */
 233 /* ARGSUSED1 */
 234 static void
 235 key(unsigned char k, int x, int y)
 236 {
 237   switch (k) {
 238   case 'z':
 239     view_rotz += 5.0;
 240     break;
 241   case 'Z':
 242     view_rotz -= 5.0;
 243     break;
 244   case 27:  /* Escape */
 245     exit(0);
 246     break;
 247   default:
 248     return;
 249   }
 250   glutPostRedisplay();
 251 }
 252
 253 /* change view angle */
 254 /* ARGSUSED1 */
 255 static void
 256 special(int k, int x, int y)
 257 {
 258   switch (k) {
 259   case GLUT_KEY_UP:
 260     view_rotx += 5.0;
 261     break;
 262   case GLUT_KEY_DOWN:
 263     view_rotx -= 5.0;
 264     break;
 265   case GLUT_KEY_LEFT:
 266     view_roty += 5.0;
 267     break;
 268   case GLUT_KEY_RIGHT:
 269     view_roty -= 5.0;
 270     break;
 271   default:
 272     return;
 273   }
 274   glutPostRedisplay();
 275 }
 276
 277 /* new window size or exposure */
 278 static void
 279 reshape(int width, int height)
 280 {
 281   GLfloat h = (GLfloat) height / (GLfloat) width;
 282
 283   glViewport(0, 0, (GLint) width, (GLint) height);
 284   glMatrixMode(GL_PROJECTION);
 285   glLoadIdentity();
 286   glFrustum(-1.0, 1.0, -h, h, 5.0, 60.0);
 287   glMatrixMode(GL_MODELVIEW);
 288   glLoadIdentity();
 289   glTranslatef(0.0, 0.0, -40.0);
 290 }
 291
 292 static void
 293 init(void)
 294 {
 295   static GLfloat pos[4] =
 296   {5.0, 5.0, 10.0, 0.0};
 297   static GLfloat red[4] =
 298   {0.8, 0.1, 0.0, 1.0};
 299   static GLfloat green[4] =
 300   {0.0, 0.8, 0.2, 1.0};
 301   static GLfloat blue[4] =
 302   {0.2, 0.2, 1.0, 1.0};
 303
 304   glLightfv(GL_LIGHT0, GL_POSITION, pos);
 305   glEnable(GL_CULL_FACE);
 306   glEnable(GL_LIGHTING);
 307   glEnable(GL_LIGHT0);
 308   glEnable(GL_DEPTH_TEST);
 309
 310   /* make the gears */
 311   gear1 = glGenLists(1);
 312   glNewList(gear1, GL_COMPILE);
 313   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
 314   gear(1.0, 4.0, 1.0, 20, 0.7);
 315   glEndList();
 316
 317   gear2 = glGenLists(1);
 318   glNewList(gear2, GL_COMPILE);
 319   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
 320   gear(0.5, 2.0, 2.0, 10, 0.7);
 321   glEndList();
 322
 323   gear3 = glGenLists(1);
 324   glNewList(gear3, GL_COMPILE);
 325   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
 326   gear(1.3, 2.0, 0.5, 10, 0.7);
 327   glEndList();
 328
 329   glEnable(GL_NORMALIZE);
 330 }
 331
 332 void
 333 visible(int vis)
 334 {
 335   if (vis == GLUT_VISIBLE)
 336     glutIdleFunc(idle);
 337   else
 338     glutIdleFunc(NULL);
 339 }
 340
 341 int main(int argc, char *argv[])
 342 {
 343   glutInit(&argc, argv);
 344   glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 345
 346   glutInitWindowPosition(0, 0);
 347   glutInitWindowSize(300, 300);
 348   glutCreateWindow("Gears");
 349   init();
 350
 351   glutDisplayFunc(draw);
 352   glutReshapeFunc(reshape);
 353   glutKeyboardFunc(key);
 354   glutSpecialFunc(special);
 355   glutVisibilityFunc(visible);
 356
 357   glutMainLoop();
 358   return 0;             /* ANSI C requires main to return int. */
 359 }