src/demos/gearbox.c

   1 /*
   2  * Use glCopyTexSubImage2D to draw animated gears on the sides of a box.
   3  *
   4  * Brian Paul
   5  * 27 January 2006
   6  */
   7
   8 #include <math.h>
   9 #include <stdlib.h>
  10 #include <stdio.h>
  11 #include <string.h>
  12 #include "glut_wrap.h"
  13
  14 #ifndef M_PI
  15 #define M_PI 3.14159265
  16 #endif
  17
  18 static GLint WinWidth = 800, WinHeight = 500;
  19 static GLint TexWidth, TexHeight;
  20 static GLuint TexObj = 1;
  21 static GLenum IntFormat = GL_RGB;
  22
  23 static GLboolean WireFrame = GL_FALSE;
  24
  25 static GLint T0 = 0;
  26 static GLint Frames = 0;
  27 static GLint Win = 0;
  28
  29 static GLfloat ViewRotX = 20.0, ViewRotY = 30.0, ViewRotZ = 0.0;
  30 static GLint Gear1, Gear2, Gear3;
  31 static GLfloat GearRot = 0.0;
  32 static GLfloat CubeRot = 0.0;
  33
  34
  35 /**
  36   Draw a gear wheel.  You'll probably want to call this function when
  37   building a display list since we do a lot of trig here.
  38
  39   Input:  inner_radius - radius of hole at center
  40           outer_radius - radius at center of teeth
  41           width - width of gear
  42           teeth - number of teeth
  43           tooth_depth - depth of tooth
  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 void
 164 cleanup(void)
 165 {
 166    glDeleteTextures(1, &TexObj);
 167    glDeleteLists(Gear1, 1);
 168    glDeleteLists(Gear2, 1);
 169    glDeleteLists(Gear3, 1);
 170    glutDestroyWindow(Win);
 171 }
 172
 173
 174 static void
 175 DrawGears(void)
 176 {
 177    if (WireFrame) {
 178       glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 179    }
 180
 181    glPushMatrix();
 182       glRotatef(20/*ViewRotX*/, 1.0, 0.0, 0.0);
 183       glRotatef(ViewRotY, 0.0, 1.0, 0.0);
 184       glRotatef(ViewRotZ, 0.0, 0.0, 1.0);
 185
 186       glPushMatrix();
 187          glTranslatef(-3.0, -2.0, 0.0);
 188          glRotatef(GearRot, 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 * GearRot - 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 * GearRot - 25.0, 0.0, 0.0, 1.0);
 201          glCallList(Gear3);
 202       glPopMatrix();
 203
 204   glPopMatrix();
 205
 206   glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
 207 }
 208
 209
 210 static void
 211 DrawCube(void)
 212 {
 213    static const GLfloat texcoords[4][2] = {
 214       { 0, 0 }, { 1, 0 }, { 1, 1 }, { 0, 1 }
 215    };
 216    static const GLfloat vertices[4][2] = {
 217       { -1, -1 }, { 1, -1 }, { 1, 1 }, { -1, 1 }
 218    };
 219    static const GLfloat xforms[6][4] = {
 220       {   0, 0, 1, 0 },
 221       {  90, 0, 1, 0 },
 222       { 180, 0, 1, 0 },
 223       { 270, 0, 1, 0 },
 224       {  90, 1, 0, 0 },
 225       { -90, 1, 0, 0 }
 226    };
 227    static const GLfloat mat[4] = { 1.0, 1.0, 0.5, 1.0 };
 228    GLint i, j;
 229
 230    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, mat);
 231    glEnable(GL_TEXTURE_2D);
 232
 233    glPushMatrix();
 234       glRotatef(ViewRotX, 1.0, 0.0, 0.0);
 235       glRotatef(15, 1, 0, 0);
 236       glRotatef(CubeRot, 0, 1, 0);
 237       glScalef(4, 4, 4);
 238
 239       for (i = 0; i < 6; i++) {
 240          glPushMatrix();
 241             glRotatef(xforms[i][0], xforms[i][1], xforms[i][2], xforms[i][3]);
 242             glTranslatef(0, 0, 1.1);
 243             glBegin(GL_POLYGON);
 244                glNormal3f(0, 0, 1);
 245                for (j = 0; j < 4; j++) {
 246                   glTexCoord2fv(texcoords[j]);
 247                   glVertex2fv(vertices[j]);
 248                }
 249             glEnd();
 250          glPopMatrix();
 251       }
 252    glPopMatrix();
 253
 254    glDisable(GL_TEXTURE_2D);
 255 }
 256
 257
 258 static void
 259 draw(void)
 260 {
 261    float ar;
 262
 263    glMatrixMode(GL_MODELVIEW);
 264    glLoadIdentity();
 265    glTranslatef(0.0, 0.0, -40.0);
 266
 267    /* clear whole depth buffer */
 268    glDisable(GL_SCISSOR_TEST);
 269    glClear(GL_DEPTH_BUFFER_BIT);
 270    glEnable(GL_SCISSOR_TEST);
 271
 272    /* clear upper-left corner of color buffer (unused space) */
 273    glScissor(0, TexHeight, TexWidth, WinHeight - TexHeight);
 274    glClearColor(0.0, 0.0, 0.0, 0.0);
 275    glClear(GL_COLOR_BUFFER_BIT);
 276
 277    /* clear lower-left corner of color buffer */
 278    glViewport(0, 0, TexWidth, TexHeight);
 279    glScissor(0, 0, TexWidth, TexHeight);
 280    glClearColor(1, 1, 1, 0);
 281    glClear(GL_COLOR_BUFFER_BIT);
 282
 283    /* draw gears in lower-left corner */
 284    glMatrixMode(GL_PROJECTION);
 285    glLoadIdentity();
 286    glFrustum(-1.0, 1.0, -1.0, 1.0, 5.0, 60.0);
 287    glMatrixMode(GL_MODELVIEW);
 288    DrawGears();
 289
 290    /* copy color buffer to texture */
 291    glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, TexWidth, TexHeight);
 292
 293    /* clear right half of color buffer */
 294    glViewport(TexWidth, 0, WinWidth - TexWidth, WinHeight);
 295    glScissor(TexWidth, 0, WinWidth - TexWidth, WinHeight);
 296    glClearColor(0.5, 0.5, 0.8, 0.0);
 297    glClear(GL_COLOR_BUFFER_BIT);
 298
 299    /* draw textured cube in right half of window */
 300    ar = (float) (WinWidth - TexWidth) / WinHeight;
 301    glMatrixMode(GL_PROJECTION);
 302    glLoadIdentity();
 303    glFrustum(-ar, ar, -1.0, 1.0, 5.0, 60.0);
 304    glMatrixMode(GL_MODELVIEW);
 305    DrawCube();
 306
 307    /* finish up */
 308    glutSwapBuffers();
 309
 310    Frames++;
 311    {
 312       GLint t = glutGet(GLUT_ELAPSED_TIME);
 313       if (t - T0 >= 5000) {
 314          GLfloat seconds = (t - T0) / 1000.0;
 315          GLfloat fps = Frames / seconds;
 316          printf("%d frames in %6.3f seconds = %6.3f FPS\n", Frames, seconds, fps);
 317          fflush(stdout);
 318          T0 = t;
 319          Frames = 0;
 320       }
 321    }
 322 }
 323
 324
 325 static void
 326 idle(void)
 327 {
 328   static double t0 = -1.;
 329   double dt, t = glutGet(GLUT_ELAPSED_TIME) / 1000.0;
 330   if (t0 < 0.0)
 331     t0 = t;
 332   dt = t - t0;
 333   t0 = t;
 334
 335   /* fmod to prevent overflow */
 336   GearRot = fmod(GearRot + 70.0 * dt, 360.0);  /* 70 deg/sec */
 337   CubeRot = fmod(CubeRot + 15.0 * dt, 360.0);  /* 15 deg/sec */
 338
 339   glutPostRedisplay();
 340 }
 341
 342
 343 /* change view angle, exit upon ESC */
 344 static void
 345 key(unsigned char k, int x, int y)
 346 {
 347    (void) x;
 348    (void) y;
 349    switch (k) {
 350    case 'w':
 351       WireFrame = !WireFrame;
 352       break;
 353    case 'z':
 354       ViewRotZ += 5.0;
 355       break;
 356    case 'Z':
 357       ViewRotZ -= 5.0;
 358       break;
 359    case 27:  /* Escape */
 360       cleanup();
 361       exit(0);
 362       break;
 363    default:
 364       return;
 365    }
 366    glutPostRedisplay();
 367 }
 368
 369 /* change view angle */
 370 static void
 371 special(int k, int x, int y)
 372 {
 373    (void) x;
 374    (void) y;
 375    switch (k) {
 376    case GLUT_KEY_UP:
 377       ViewRotX += 5.0;
 378       break;
 379    case GLUT_KEY_DOWN:
 380       ViewRotX -= 5.0;
 381       break;
 382    case GLUT_KEY_LEFT:
 383       ViewRotY += 5.0;
 384       break;
 385    case GLUT_KEY_RIGHT:
 386       ViewRotY -= 5.0;
 387       break;
 388    default:
 389       return;
 390    }
 391    glutPostRedisplay();
 392 }
 393
 394
 395 /* new window size or exposure */
 396 static void
 397 reshape(int width, int height)
 398 {
 399   WinWidth = width;
 400   WinHeight = height;
 401 }
 402
 403
 404 static void
 405 init(int argc, char *argv[])
 406 {
 407   static GLfloat pos[4] = {5.0, 5.0, 10.0, 0.0};
 408   static GLfloat red[4] = {0.8, 0.1, 0.0, 1.0};
 409   static GLfloat green[4] = {0.0, 0.8, 0.2, 1.0};
 410   static GLfloat blue[4] = {0.2, 0.2, 1.0, 1.0};
 411   GLint i;
 412
 413   glLightfv(GL_LIGHT0, GL_POSITION, pos);
 414 #if 0
 415   glEnable(GL_CULL_FACE);
 416 #endif
 417   glEnable(GL_LIGHTING);
 418   glEnable(GL_LIGHT0);
 419   glEnable(GL_DEPTH_TEST);
 420
 421   /* make the gears */
 422   Gear1 = glGenLists(1);
 423   glNewList(Gear1, GL_COMPILE);
 424   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
 425   gear(1.0, 4.0, 1.0, 20, 0.7);
 426   glEndList();
 427
 428   Gear2 = glGenLists(1);
 429   glNewList(Gear2, GL_COMPILE);
 430   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
 431   gear(0.5, 2.0, 2.0, 10, 0.7);
 432   glEndList();
 433
 434   Gear3 = glGenLists(1);
 435   glNewList(Gear3, GL_COMPILE);
 436   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
 437   gear(1.3, 2.0, 0.5, 10, 0.7);
 438   glEndList();
 439
 440   glEnable(GL_NORMALIZE);
 441
 442   /* xxx make size dynamic */
 443   TexWidth = 256;
 444   TexHeight = 256;
 445
 446    glBindTexture(GL_TEXTURE_2D, TexObj);
 447    glTexImage2D(GL_TEXTURE_2D, 0, IntFormat, TexWidth, TexHeight, 0,
 448                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);
 449    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 450    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 451    glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
 452
 453   for ( i=1; i<argc; i++ ) {
 454     if (strcmp(argv[i], "-info")==0) {
 455       printf("GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
 456       printf("GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
 457       printf("GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
 458       printf("GL_EXTENSIONS = %s\n", (char *) glGetString(GL_EXTENSIONS));
 459     }
 460   }
 461 }
 462
 463
 464 static void
 465 visible(int vis)
 466 {
 467   if (vis == GLUT_VISIBLE)
 468     glutIdleFunc(idle);
 469   else
 470     glutIdleFunc(NULL);
 471 }
 472
 473
 474 int
 475 main(int argc, char *argv[])
 476 {
 477    glutInitWindowSize(WinWidth, WinHeight);
 478    glutInit(&argc, argv);
 479    glutInitDisplayMode(GLUT_RGB | GLUT_DEPTH | GLUT_DOUBLE);
 480
 481    Win = glutCreateWindow("gearbox");
 482    init(argc, argv);
 483
 484    glutDisplayFunc(draw);
 485    glutReshapeFunc(reshape);
 486    glutKeyboardFunc(key);
 487    glutSpecialFunc(special);
 488    glutVisibilityFunc(visible);
 489
 490    glutMainLoop();
 491    return 0;             /* ANSI C requires main to return int. */
 492 }