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


typedef struct Vec3f { 
  float x, y, z;
};

Vec3f * particle_pos;
Vec3f * particle_color;
Vec3f * particle_dir;
int num_particles;


void renderProcDraw ();
void appProcCompute ();

void main (int argc, char ** argv)
{
  num_particles = 100;
  CAVEConfigure (&argc, argv, NULL);
  if (argc == 2) {
    num_particles = atof(argv[1]);
  }
  fprintf(stdout, "simulating firework with %d particles\n", num_particles);

  // Allocate and initialize shared memory variables.
  particle_pos = (Vec3f *) CAVEMalloc (num_particles * sizeof (Vec3f));
  particle_color = (Vec3f *) CAVEMalloc (num_particles * sizeof (Vec3f));
  for (int i = 0; i < num_particles; i++) {
    particle_pos[i].x = 0;
    particle_pos[i].y = 4;
    particle_pos[i].z = -3;
    particle_color[i].x = drand48();
    particle_color[i].y = drand48();
    particle_color[i].z = drand48();
  }
  
  CAVEInit (); // fork!

  CAVEDisplay (renderProcDraw, 0);
  
  // initialize particle directions - only needed by 
  particle_dir = (Vec3f *) malloc(num_particles * sizeof (Vec3f));
  for (i = 0; i < num_particles; i++) {
    ///// pick direction at random
    //particle_dir[i].x = 2 * drand48() - 1;
    //particle_dir[i].y = 2 * drand48() - 1;
    //particle_dir[i].z = 2 * drand48() - 1;
    //// or based on color of particle;
    particle_dir[i].x = 2 * particle_color[i].x - 1;
    particle_dir[i].y = 2 * particle_color[i].y - 1;
    particle_dir[i].z = 2 * particle_color[i].z - 1;
  }
  
  while (!CAVEgetbutton (CAVE_ESCKEY)) {
    //block until all drawing processes have completed current frame
    //CAVEDisplaySync();  
    appProcCompute ();
    sginap (10);
  }

  // clean up (explicitly)
  CAVEFree(particle_pos);
  CAVEFree(particle_color);
  free(particle_dir);

  CAVEExit ();
}


#define SPEED 0.2;

void appProcCompute ()
{
  static int nCalls = 0;
  static float prev_t = 0; 
  float t, dt;     

  t = CAVEGetTime ();
  dt = t - prev_t;
  prev_t = t;

  fprintf(stdout, "(%d) COMPUTE: %d", getpid(), nCalls++);
  fflush(stdout);

  for (int i = 0; i < num_particles; i++) {
    particle_pos[i].x += particle_dir[i].x * dt * SPEED;
    particle_pos[i].y += particle_dir[i].y * dt * SPEED;
    particle_pos[i].z += particle_dir[i].z * dt * SPEED;
  }
  
  fprintf(stdout, "...COMPUTE DONE\n");

}


void renderProcDraw ()
{
  static int nCalls = 0;

  glClearColor (0.2, 0.2, 0.8, 1.0);
  glClear (GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);


  fprintf (stdout, "(%d)  render: %d", getpid(), nCalls++);
  fflush(stdout);

  glBegin(GL_POINTS);
  for (int i = 0; i < num_particles; i++) {
    glColor3f (particle_color[i].x, particle_color[i].y, particle_color[i].z);
    glVertex3f(particle_pos[i].x, particle_pos[i].y, particle_pos[i].z);
  }
  glEnd();

  fprintf(stdout, "...render done\n");

}