progs/demos/bounce.c

   1
   2 /*
   3  * Bouncing ball demo.
   4  *
   5  * This program is in the public domain
   6  *
   7  * Brian Paul
   8  *
   9  * Conversion to GLUT by Mark J. Kilgard
  10  */
  11
  12
  13 #include <math.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <GL/glut.h>
  17
  18 #define COS(X)   cos( (X) * 3.14159/180.0 )
  19 #define SIN(X)   sin( (X) * 3.14159/180.0 )
  20
  21 #define RED 1
  22 #define WHITE 2
  23 #define CYAN 3
  24
  25 GLboolean IndexMode = GL_FALSE;
  26 GLuint Ball;
  27 GLenum Mode;
  28 GLfloat Zrot = 0.0, Zstep = 180.0;
  29 GLfloat Xpos = 0.0, Ypos = 1.0;
  30 GLfloat Xvel = 2.0, Yvel = 0.0;
  31 GLfloat Xmin = -4.0, Xmax = 4.0;
  32 GLfloat Ymin = -3.8, Ymax = 4.0;
  33 GLfloat G = -9.8;
  34
  35 static GLuint
  36 make_ball(void)
  37 {
  38   GLuint list;
  39   GLfloat a, b;
  40   GLfloat da = 18.0, db = 18.0;
  41   GLfloat radius = 1.0;
  42   GLuint color;
  43   GLfloat x, y, z;
  44
  45   list = glGenLists(1);
  46
  47   glNewList(list, GL_COMPILE);
  48
  49   color = 0;
  50   for (a = -90.0; a + da <= 90.0; a += da) {
  51
  52     glBegin(GL_QUAD_STRIP);
  53     for (b = 0.0; b <= 360.0; b += db) {
  54
  55       if (color) {
  56         glIndexi(RED);
  57         glColor3f(1, 0, 0);
  58       } else {
  59         glIndexi(WHITE);
  60         glColor3f(1, 1, 1);
  61       }
  62
  63       x = radius * COS(b) * COS(a);
  64       y = radius * SIN(b) * COS(a);
  65       z = radius * SIN(a);
  66       glVertex3f(x, y, z);
  67
  68       x = radius * COS(b) * COS(a + da);
  69       y = radius * SIN(b) * COS(a + da);
  70       z = radius * SIN(a + da);
  71       glVertex3f(x, y, z);
  72
  73       color = 1 - color;
  74     }
  75     glEnd();
  76
  77   }
  78
  79   glEndList();
  80
  81   return list;
  82 }
  83
  84 static void
  85 reshape(int width, int height)
  86 {
  87   float aspect = (float) width / (float) height;
  88   glViewport(0, 0, (GLint) width, (GLint) height);
  89   glMatrixMode(GL_PROJECTION);
  90   glLoadIdentity();
  91   glOrtho(-6.0 * aspect, 6.0 * aspect, -6.0, 6.0, -6.0, 6.0);
  92   glMatrixMode(GL_MODELVIEW);
  93 }
  94
  95 /* ARGSUSED1 */
  96 static void
  97 key(unsigned char k, int x, int y)
  98 {
  99   switch (k) {
 100   case 27:  /* Escape */
 101     exit(0);
 102   }
 103 }
 104
 105 static void
 106 draw(void)
 107 {
 108   GLint i;
 109
 110   glClear(GL_COLOR_BUFFER_BIT);
 111
 112   glIndexi(CYAN);
 113   glColor3f(0, 1, 1);
 114   glBegin(GL_LINES);
 115   for (i = -5; i <= 5; i++) {
 116     glVertex2i(i, -5);
 117     glVertex2i(i, 5);
 118   }
 119   for (i = -5; i <= 5; i++) {
 120     glVertex2i(-5, i);
 121     glVertex2i(5, i);
 122   }
 123   for (i = -5; i <= 5; i++) {
 124     glVertex2i(i, -5);
 125     glVertex2f(i * 1.15, -5.9);
 126   }
 127   glVertex2f(-5.3, -5.35);
 128   glVertex2f(5.3, -5.35);
 129   glVertex2f(-5.75, -5.9);
 130   glVertex2f(5.75, -5.9);
 131   glEnd();
 132
 133   glPushMatrix();
 134   glTranslatef(Xpos, Ypos, 0.0);
 135   glScalef(2.0, 2.0, 2.0);
 136   glRotatef(8.0, 0.0, 0.0, 1.0);
 137   glRotatef(90.0, 1.0, 0.0, 0.0);
 138   glRotatef(Zrot, 0.0, 0.0, 1.0);
 139
 140   glCallList(Ball);
 141
 142   glPopMatrix();
 143
 144   glFlush();
 145   glutSwapBuffers();
 146 }
 147
 148 static void
 149 idle(void)
 150 {
 151   static float vel0 = -100.0;
 152   static double t0 = -1.;
 153   double t, dt;
 154   t = glutGet(GLUT_ELAPSED_TIME) / 1000.;
 155   if (t0 < 0.)
 156      t0 = t;
 157   dt = t - t0;
 158   t0 = t;
 159
 160   Zrot += Zstep*dt;
 161
 162   Xpos += Xvel*dt;
 163   if (Xpos >= Xmax) {
 164     Xpos = Xmax;
 165     Xvel = -Xvel;
 166     Zstep = -Zstep;
 167   }
 168   if (Xpos <= Xmin) {
 169     Xpos = Xmin;
 170     Xvel = -Xvel;
 171     Zstep = -Zstep;
 172   }
 173   Ypos += Yvel*dt;
 174   Yvel += G*dt;
 175   if (Ypos < Ymin) {
 176     Ypos = Ymin;
 177     if (vel0 == -100.0)
 178       vel0 = fabs(Yvel);
 179     Yvel = vel0;
 180   }
 181   glutPostRedisplay();
 182 }
 183
 184 static void
 185 visible(int vis)
 186 {
 187   if (vis == GLUT_VISIBLE)
 188     glutIdleFunc(idle);
 189   else
 190     glutIdleFunc(NULL);
 191 }
 192
 193 int main(int argc, char *argv[])
 194 {
 195   glutInit(&argc, argv);
 196   glutInitWindowPosition(0, 0);
 197   glutInitWindowSize(600, 450);
 198
 199
 200   IndexMode = argc > 1 && strcmp(argv[1], "-ci") == 0;
 201   if (IndexMode)
 202      glutInitDisplayMode(GLUT_INDEX | GLUT_DOUBLE);
 203   else
 204      glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 205
 206   glutCreateWindow("Bounce");
 207   Ball = make_ball();
 208   glCullFace(GL_BACK);
 209   glEnable(GL_CULL_FACE);
 210   glDisable(GL_DITHER);
 211   glShadeModel(GL_FLAT);
 212
 213   glutDisplayFunc(draw);
 214   glutReshapeFunc(reshape);
 215   glutVisibilityFunc(visible);
 216   glutKeyboardFunc(key);
 217
 218   if (IndexMode) {
 219     glutSetColor(RED, 1.0, 0.0, 0.0);
 220     glutSetColor(WHITE, 1.0, 1.0, 1.0);
 221     glutSetColor(CYAN, 0.0, 1.0, 1.0);
 222   }
 223
 224   glutMainLoop();
 225   return 0;             /* ANSI C requires main to return int. */
 226 }