#include "log.h"
#include "physics.h"
#include "opengl.h"
#include "rng.h"
#include "pilot.h"
#include "space.h"

#define STAR_BUF 100 // Area to leave around screen.
typedef struct {
  Vec2 pos;
  double brightness;
} Star;

Star* stars;
int nstars;

void space_init(void) {
  int i;
  nstars = (500*gl_screen.w*gl_screen.h + STAR_BUF*STAR_BUF)/(800*640);;
  stars = malloc(sizeof(Star)*nstars);
  for(i = 0; i < nstars; i++) {
    stars[i].brightness = (double)RNG(50, 200)/256.;
    stars[i].pos.x = (double)RNG(-STAR_BUF, gl_screen.w + STAR_BUF);
    stars[i].pos.y = (double)RNG(-STAR_BUF, gl_screen.h + STAR_BUF);
  }
}

void space_render(double dt) {
  int i;
  glMatrixMode(GL_PROJECTION);
  glPushMatrix(); // Projection translation matrix.
  glTranslated(-(double)gl_screen.w/2., -(double)gl_screen.h/2., 0.);
  glBegin(GL_POINTS);
  for(i = 0; i < nstars; i++) {
    // Update the position.
    stars[i].pos.x -= player->solid->vel.x/(15.-10.*stars[i].brightness)*dt;
    stars[i].pos.y -= player->solid->vel.y/(15.-10.*stars[i].brightness)*dt;
    // Scroll those stars bitch!
    if(stars[i].pos.x > gl_screen.w + STAR_BUF) stars[i].pos.x = -STAR_BUF;
    else if(stars[i].pos.x < -STAR_BUF) stars[i].pos.x = gl_screen.w + STAR_BUF;
    if(stars[i].pos.y > gl_screen.h + STAR_BUF) stars[i].pos.y = -STAR_BUF;
    else if(stars[i].pos.y < -STAR_BUF) stars[i].pos.y = gl_screen.h + STAR_BUF;
    // Render.
    glColor4d(1., 1., 1., stars[i].brightness);
    glVertex2d(stars[i].pos.x, stars[i].pos.y);
  }
  glEnd();
  glPopMatrix(); // Projection translation matrix.
}

void space_exit(void) {
  free(stars);
}