progs/ggi/gears.c

   1
   2 /*
   3  * 3-D gear wheels.  This program is in the public domain.
   4  *
   5  * Brian Paul
   6  */
   7
   8 /* Conversion to GLUT by Mark J. Kilgard */
   9
  10 #include <math.h>
  11 #include <stdlib.h>
  12 #include <stdio.h>
  13 #include <GL/glut.h>
  14
  15 #ifndef M_PI
  16 #define M_PI 3.14159265
  17 #endif
  18
  19 static GLint T0 = 0;
  20 static GLint Frames = 0;
  21
  22
  23 /**
  24
  25   Draw a gear wheel.  You'll probably want to call this function when
  26   building a display list since we do a lot of trig here.
  27
  28   Input:  inner_radius - radius of hole at center
  29           outer_radius - radius at center of teeth
  30           width - width of gear
  31           teeth - number of teeth
  32           tooth_depth - depth of tooth
  33
  34  **/
  35
  36 static void
  37 gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
  38   GLint teeth, GLfloat tooth_depth)
  39 {
  40   GLint i;
  41   GLfloat r0, r1, r2;
  42   GLfloat angle, da;
  43   GLfloat u, v, len;
  44
  45   r0 = inner_radius;
  46   r1 = outer_radius - tooth_depth / 2.0;
  47   r2 = outer_radius + tooth_depth / 2.0;
  48
  49   da = 2.0 * M_PI / teeth / 4.0;
  50
  51   glShadeModel(GL_FLAT);
  52
  53   glNormal3f(0.0, 0.0, 1.0);
  54
  55   /* draw front face */
  56   glBegin(GL_QUAD_STRIP);
  57   for (i = 0; i <= teeth; i++) {
  58     angle = i * 2.0 * M_PI / teeth;
  59     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  60     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  61     if (i < teeth) {
  62       glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
  63       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  64     }
  65   }
  66   glEnd();
  67
  68   /* draw front sides of teeth */
  69   glBegin(GL_QUADS);
  70   da = 2.0 * M_PI / teeth / 4.0;
  71   for (i = 0; i < teeth; i++) {
  72     angle = i * 2.0 * M_PI / teeth;
  73
  74     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
  75     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
  76     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
  77     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
  78   }
  79   glEnd();
  80
  81   glNormal3f(0.0, 0.0, -1.0);
  82
  83   /* draw back face */
  84   glBegin(GL_QUAD_STRIP);
  85   for (i = 0; i <= teeth; i++) {
  86     angle = i * 2.0 * M_PI / teeth;
  87     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
  88     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
  89     if (i < teeth) {
  90       glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
  91       glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
  92     }
  93   }
  94   glEnd();
  95
  96   /* draw back sides of teeth */
  97   glBegin(GL_QUADS);
  98   da = 2.0 * M_PI / teeth / 4.0;
  99   for (i = 0; i < teeth; i++) {
 100     angle = i * 2.0 * M_PI / teeth;
 101
 102     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 103     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 104     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 105     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 106   }
 107   glEnd();
 108
 109   /* draw outward faces of teeth */
 110   glBegin(GL_QUAD_STRIP);
 111   for (i = 0; i < teeth; i++) {
 112     angle = i * 2.0 * M_PI / teeth;
 113
 114     glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
 115     glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
 116     u = r2 * cos(angle + da) - r1 * cos(angle);
 117     v = r2 * sin(angle + da) - r1 * sin(angle);
 118     len = sqrt(u * u + v * v);
 119     u /= len;
 120     v /= len;
 121     glNormal3f(v, -u, 0.0);
 122     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
 123     glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
 124     glNormal3f(cos(angle), sin(angle), 0.0);
 125     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), width * 0.5);
 126     glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da), -width * 0.5);
 127     u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
 128     v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
 129     glNormal3f(v, -u, 0.0);
 130     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), width * 0.5);
 131     glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da), -width * 0.5);
 132     glNormal3f(cos(angle), sin(angle), 0.0);
 133   }
 134
 135   glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
 136   glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);
 137
 138   glEnd();
 139
 140   glShadeModel(GL_SMOOTH);
 141
 142   /* draw inside radius cylinder */
 143   glBegin(GL_QUAD_STRIP);
 144   for (i = 0; i <= teeth; i++) {
 145     angle = i * 2.0 * M_PI / teeth;
 146     glNormal3f(-cos(angle), -sin(angle), 0.0);
 147     glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
 148     glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
 149   }
 150   glEnd();
 151
 152 }
 153
 154 static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
 155 static GLint gear1, gear2, gear3;
 156 static GLfloat angle = 0.0;
 157
 158 static void
 159 draw(void)
 160 {
 161   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 162
 163   glPushMatrix();
 164   glRotatef(view_rotx, 1.0, 0.0, 0.0);
 165   glRotatef(view_roty, 0.0, 1.0, 0.0);
 166   glRotatef(view_rotz, 0.0, 0.0, 1.0);
 167
 168   glPushMatrix();
 169   glTranslatef(-3.0, -2.0, 0.0);
 170   glRotatef(angle, 0.0, 0.0, 1.0);
 171   glCallList(gear1);
 172   glPopMatrix();
 173
 174   glPushMatrix();
 175   glTranslatef(3.1, -2.0, 0.0);
 176   glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
 177   glCallList(gear2);
 178   glPopMatrix();
 179
 180   glPushMatrix();
 181   glTranslatef(-3.1, 4.2, 0.0);
 182   glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
 183   glCallList(gear3);
 184   glPopMatrix();
 185
 186   glPopMatrix();
 187
 188   glutSwapBuffers();
 189
 190   Frames++;
 191   {
 192      GLint t = glutGet(GLUT_ELAPSED_TIME);
 193      if (t - T0 >= 5000) {
 194         GLfloat seconds = (t - T0) / 1000.0;
 195         GLfloat fps = Frames / seconds;
 196         printf("%d frames in %g seconds = %g FPS\n", Frames, seconds, fps);
 197         T0 = t;
 198         Frames = 0;
 199      }
 200   }
 201 }
 202
 203
 204 static void
 205 idle(void)
 206 {
 207   angle += 2.0;
 208   glutPostRedisplay();
 209 }
 210
 211 /* change view angle, exit upon ESC */
 212 /* ARGSUSED1 */
 213 static void
 214 key(unsigned char k, int x, int y)
 215 {
 216   switch (k) {
 217   case 'z':
 218     view_rotz += 5.0;
 219     break;
 220   case 'Z':
 221     view_rotz -= 5.0;
 222     break;
 223   case 27:  /* Escape */
 224     exit(0); /* FIXME: Shutdown and free resources cleanly in ggiglut */
 225     break;
 226   default:
 227     return;
 228   }
 229   glutPostRedisplay();
 230 }
 231
 232 /* change view angle */
 233 /* ARGSUSED1 */
 234 static void
 235 special(int k, int x, int y)
 236 {
 237   switch (k) {
 238   case GLUT_KEY_UP:
 239     view_rotx += 5.0;
 240     break;
 241   case GLUT_KEY_DOWN:
 242     view_rotx -= 5.0;
 243     break;
 244   case GLUT_KEY_LEFT:
 245     view_roty += 5.0;
 246     break;
 247   case GLUT_KEY_RIGHT:
 248     view_roty -= 5.0;
 249     break;
 250   default:
 251     return;
 252   }
 253   glutPostRedisplay();
 254 }
 255
 256 /* new window size or exposure */
 257 static void
 258 reshape(int width, int height)
 259 {
 260   GLfloat h = (GLfloat) height / (GLfloat) width;
 261
 262   glViewport(0, 0, (GLint) width, (GLint) height);
 263   glMatrixMode(GL_PROJECTION);
 264   glLoadIdentity();
 265   glFrustum(-1.0, 1.0, -h, h, 5.0, 60.0);
 266   glMatrixMode(GL_MODELVIEW);
 267   glLoadIdentity();
 268   glTranslatef(0.0, 0.0, -40.0);
 269 }
 270
 271 static void
 272 init(void)
 273 {
 274   static GLfloat pos[4] =
 275   {5.0, 5.0, 10.0, 0.0};
 276   static GLfloat red[4] =
 277   {0.8, 0.1, 0.0, 1.0};
 278   static GLfloat green[4] =
 279   {0.0, 0.8, 0.2, 1.0};
 280   static GLfloat blue[4] =
 281   {0.2, 0.2, 1.0, 1.0};
 282
 283   glLightfv(GL_LIGHT0, GL_POSITION, pos);
 284   glEnable(GL_CULL_FACE);
 285   glEnable(GL_LIGHTING);
 286   glEnable(GL_LIGHT0);
 287   glEnable(GL_DEPTH_TEST);
 288
 289   /* make the gears */
 290   gear1 = glGenLists(1);
 291   glNewList(gear1, GL_COMPILE);
 292   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
 293   gear(1.0, 4.0, 1.0, 20, 0.7);
 294   glEndList();
 295
 296   gear2 = glGenLists(1);
 297   glNewList(gear2, GL_COMPILE);
 298   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
 299   gear(0.5, 2.0, 2.0, 10, 0.7);
 300   glEndList();
 301
 302   gear3 = glGenLists(1);
 303   glNewList(gear3, GL_COMPILE);
 304   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
 305   gear(1.3, 2.0, 0.5, 10, 0.7);
 306   glEndList();
 307
 308   glEnable(GL_NORMALIZE);
 309 }
 310
 311 void
 312 visible(int vis)
 313 {
 314   if (vis == GLUT_VISIBLE)
 315     glutIdleFunc(idle);
 316   else
 317     glutIdleFunc(NULL);
 318 }
 319
 320 int main(int argc, char *argv[])
 321 {
 322         glutInit(&argc, argv);
 323         glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 324
 325 //      glutInitWindowPosition(0, 0);
 326 //      glutInitWindowSize(300, 300);
 327         glutCreateWindow("Gears");
 328         init();
 329
 330         glutDisplayFunc(draw);
 331         glutReshapeFunc(reshape);
 332         glutKeyboardFunc(key);
 333         glutSpecialFunc(special);
 334         glutVisibilityFunc(visible);
 335
 336         glutMainLoop();
 337
 338         return 0;
 339 }