progs/demos/bounce.c

   1 /* $Id: bounce.c,v 1.3 2000/08/16 20:36:34 brianp Exp $ */
   2
   3 /*
   4  * Bouncing ball demo.
   5  *
   6  * This program is in the public domain
   7  *
   8  * Brian Paul
   9  *
  10  * Conversion to GLUT by Mark J. Kilgard
  11  */
  12
  13
  14 #include <math.h>
  15 #include <stdlib.h>
  16 #include <string.h>
  17 #include <GL/glut.h>
  18
  19 #define COS(X)   cos( (X) * 3.14159/180.0 )
  20 #define SIN(X)   sin( (X) * 3.14159/180.0 )
  21
  22 #define RED 1
  23 #define WHITE 2
  24 #define CYAN 3
  25
  26 GLboolean IndexMode = GL_FALSE;
  27 GLuint Ball;
  28 GLenum Mode;
  29 GLfloat Zrot = 0.0, Zstep = 6.0;
  30 GLfloat Xpos = 0.0, Ypos = 1.0;
  31 GLfloat Xvel = 0.2, Yvel = 0.0;
  32 GLfloat Xmin = -4.0, Xmax = 4.0;
  33 GLfloat Ymin = -3.8, Ymax = 4.0;
  34 GLfloat G = -0.1;
  35
  36 static GLuint
  37 make_ball(void)
  38 {
  39   GLuint list;
  40   GLfloat a, b;
  41   GLfloat da = 18.0, db = 18.0;
  42   GLfloat radius = 1.0;
  43   GLuint color;
  44   GLfloat x, y, z;
  45
  46   list = glGenLists(1);
  47
  48   glNewList(list, GL_COMPILE);
  49
  50   color = 0;
  51   for (a = -90.0; a + da <= 90.0; a += da) {
  52
  53     glBegin(GL_QUAD_STRIP);
  54     for (b = 0.0; b <= 360.0; b += db) {
  55
  56       if (color) {
  57         glIndexi(RED);
  58         glColor3f(1, 0, 0);
  59       } else {
  60         glIndexi(WHITE);
  61         glColor3f(1, 1, 1);
  62       }
  63
  64       x = radius * COS(b) * COS(a);
  65       y = radius * SIN(b) * COS(a);
  66       z = radius * SIN(a);
  67       glVertex3f(x, y, z);
  68
  69       x = radius * COS(b) * COS(a + da);
  70       y = radius * SIN(b) * COS(a + da);
  71       z = radius * SIN(a + da);
  72       glVertex3f(x, y, z);
  73
  74       color = 1 - color;
  75     }
  76     glEnd();
  77
  78   }
  79
  80   glEndList();
  81
  82   return list;
  83 }
  84
  85 static void
  86 reshape(int width, int height)
  87 {
  88   float aspect = (float) width / (float) height;
  89   glViewport(0, 0, (GLint) width, (GLint) height);
  90   glMatrixMode(GL_PROJECTION);
  91   glLoadIdentity();
  92   glOrtho(-6.0 * aspect, 6.0 * aspect, -6.0, 6.0, -6.0, 6.0);
  93   glMatrixMode(GL_MODELVIEW);
  94 }
  95
  96 /* ARGSUSED1 */
  97 static void
  98 key(unsigned char k, int x, int y)
  99 {
 100   switch (k) {
 101   case 27:  /* Escape */
 102     exit(0);
 103   }
 104 }
 105
 106 static void
 107 draw(void)
 108 {
 109   GLint i;
 110
 111   glClear(GL_COLOR_BUFFER_BIT);
 112
 113   glIndexi(CYAN);
 114   glColor3f(0, 1, 1);
 115   glBegin(GL_LINES);
 116   for (i = -5; i <= 5; i++) {
 117     glVertex2i(i, -5);
 118     glVertex2i(i, 5);
 119   }
 120   for (i = -5; i <= 5; i++) {
 121     glVertex2i(-5, i);
 122     glVertex2i(5, i);
 123   }
 124   for (i = -5; i <= 5; i++) {
 125     glVertex2i(i, -5);
 126     glVertex2f(i * 1.15, -5.9);
 127   }
 128   glVertex2f(-5.3, -5.35);
 129   glVertex2f(5.3, -5.35);
 130   glVertex2f(-5.75, -5.9);
 131   glVertex2f(5.75, -5.9);
 132   glEnd();
 133
 134   glPushMatrix();
 135   glTranslatef(Xpos, Ypos, 0.0);
 136   glScalef(2.0, 2.0, 2.0);
 137   glRotatef(8.0, 0.0, 0.0, 1.0);
 138   glRotatef(90.0, 1.0, 0.0, 0.0);
 139   glRotatef(Zrot, 0.0, 0.0, 1.0);
 140
 141   glCallList(Ball);
 142
 143   glPopMatrix();
 144
 145   glFlush();
 146   glutSwapBuffers();
 147 }
 148
 149 static void
 150 idle(void)
 151 {
 152   static float vel0 = -100.0;
 153
 154   Zrot += Zstep;
 155
 156   Xpos += Xvel;
 157   if (Xpos >= Xmax) {
 158     Xpos = Xmax;
 159     Xvel = -Xvel;
 160     Zstep = -Zstep;
 161   }
 162   if (Xpos <= Xmin) {
 163     Xpos = Xmin;
 164     Xvel = -Xvel;
 165     Zstep = -Zstep;
 166   }
 167   Ypos += Yvel;
 168   Yvel += G;
 169   if (Ypos < Ymin) {
 170     Ypos = Ymin;
 171     if (vel0 == -100.0)
 172       vel0 = fabs(Yvel);
 173     Yvel = vel0;
 174   }
 175   glutPostRedisplay();
 176 }
 177
 178 static void
 179 visible(int vis)
 180 {
 181   if (vis == GLUT_VISIBLE)
 182     glutIdleFunc(idle);
 183   else
 184     glutIdleFunc(NULL);
 185 }
 186
 187 int main(int argc, char *argv[])
 188 {
 189   glutInit(&argc, argv);
 190   glutInitWindowPosition(0, 0);
 191   glutInitWindowSize(600, 450);
 192
 193
 194   IndexMode = argc > 1 && strcmp(argv[1], "-ci") == 0;
 195   if (IndexMode)
 196      glutInitDisplayMode(GLUT_INDEX | GLUT_DOUBLE);
 197   else
 198      glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
 199
 200   glutCreateWindow("Bounce");
 201   Ball = make_ball();
 202   glCullFace(GL_BACK);
 203   glEnable(GL_CULL_FACE);
 204   glDisable(GL_DITHER);
 205   glShadeModel(GL_FLAT);
 206
 207   glutDisplayFunc(draw);
 208   glutReshapeFunc(reshape);
 209   glutVisibilityFunc(visible);
 210   glutKeyboardFunc(key);
 211
 212   if (IndexMode) {
 213     glutSetColor(RED, 1.0, 0.0, 0.0);
 214     glutSetColor(WHITE, 1.0, 1.0, 1.0);
 215     glutSetColor(CYAN, 0.0, 1.0, 1.0);
 216   }
 217
 218   glutMainLoop();
 219   return 0;             /* ANSI C requires main to return int. */
 220 }