// File: bounce.cc

// Summary: Draw single sphere.  Bounce sphere up and down.  Use CAVE
// shared memory to communicate between compute and render processes
// about new sphere position.

#include <unistd.h>
#include <GL/gl.h>
#include <GL/glu.h>
#include <cave_ogl.h>

// How high to bounce.
#define MAX_BOUNCE 8.0
// Offset so that sphere doesn't bounce through floor.
#define OFFSET     1.0
// How fast to bounce
#define DELTA 0.2

float * height;

void renderProcDraw ();
void appProcCompute ();

void main (int argc, char ** argv)
{
  // Configure based on system files and user-supplied args.
  CAVEConfigure (&argc, argv, NULL);

  // Allocate and initialize shared memory variable.
  height = (float *) CAVEMalloc (sizeof (float));
  *height = 0.0;

  // Fork rendering processes for each wall.
  CAVEInit ();

  // Specify application's drawing routine.
  CAVEDisplay (renderProcDraw, 0);

  // Let balls rise and fall over time.
  while (!CAVEgetbutton (CAVE_ESCKEY)) {
    appProcCompute ();
    sginap (10);
  }

  CAVEFree (height);
  CAVEExit ();
}


void appProcCompute ()
{
  static int nCalls = 0;
  float t;
  //static float t = 0; 
  //t += DELTA;         
  t = CAVEGetTime ();
  CAVEDisplaySync();
  printf ("(%d) compute: %d\n", getpid(), nCalls++);
  *height = fabs (sin (t)) * MAX_BOUNCE + OFFSET;
}


void renderProcDraw ()
{
  static int nCalls = 0;

  // Clear the z-buffer and set the screen to blue.
  glClearColor (0.2, 0.2, 0.8, 1.0);
  glClear (GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);

  glPushMatrix ();
  glTranslatef (0, *height, -4);

  glColor3f (1.0, 1.0, 0.0);
  GLUquadric * quad = gluNewQuadric ();
  gluSphere (quad, 1.0, 20, 20);

  // Reset the transformation matrix.
  glPopMatrix ();

  printf ("(%d)  render: %d\n", getpid(), nCalls++);
  
}