/*
Starfield Lib

Coded by Jeff Lawton (aka Zark Wizard)
Group Nemesis   - May 29 - 1998

Visit our home site at : http://yaroze-world.org
*/

#include "starslib.h"

static star_points star_pnts[MAX_STARS];
static GsLINE starfield;
static int star_dir, star_cnt, star_x, star_y, star_w, star_h, star_on;  // Area of current star field.

GsOT *TheOT;

/////////////////////////////////////////////////////////////
// Starfield Stuff
/////////////////////////////////////////////////////////////

void star_field(int cnt, int dir, int x, int y, int h, int w) {
  int i;

  if (cnt > MAX_STARS) 
    cnt = MAX_STARS;

  star_cnt = cnt;
  star_x = x;  
  star_y = y;  
  star_w = w;  
  star_h = h;
  star_dir = dir;  
  for (i = 0; i < cnt; i++) {
    star_pnts[i].x  = x + (rand()%(w - x));
    star_pnts[i].y  = y + (rand()%(h - y));

    starfield.attribute = 0;
    switch(rand()%MAX_FIELDS) {
      // slowest -> fastest
      case	0:	star_pnts[i].vel = 1;
          			star_pnts[i].depth = 62;
                break;
      case	1:	star_pnts[i].vel = 2;
           			star_pnts[i].depth = 128;
                break;
      case	2:	star_pnts[i].vel = 3;
           			star_pnts[i].depth = 196;
                break;
      case	3:	star_pnts[i].vel = 4;
          			star_pnts[i].depth = 250;
                break;
    }
    starfield.r = starfield.g = starfield.b = star_pnts[i].depth;
    
  }
}

void ani_stars(void) {
  int i;

	for (i = 0; i < star_cnt; i++) {
    switch(star_dir) {
      case STAR_U :  // up
                star_pnts[i].y -= star_pnts[i].vel;
              	if (star_pnts[i].y <= star_y) 
                  star_pnts[i].y = star_pnts[i].y = (star_y + star_h);
                break;
      case STAR_D :  // down
               	star_pnts[i].y += star_pnts[i].vel;
              	if (star_pnts[i].y >= (star_h + star_y)) 
                  star_pnts[i].y = star_y;
                break;
      case STAR_R :  // right
               	star_pnts[i].x += star_pnts[i].vel;
              	if (star_pnts[i].x >= (star_w + star_x)) 
                  star_pnts[i].x = star_x;
                break;
      case STAR_L :  // left
               	star_pnts[i].x -= star_pnts[i].vel;
              	if (star_pnts[i].x <= star_x) 
                  star_pnts[i].x = (star_w + star_x);
                break;
    
    }

    starfield.x0 = starfield.x1 = star_pnts[i].x;
    starfield.y0 = starfield.y1 = star_pnts[i].y;
    starfield.r = starfield.g = starfield.b = star_pnts[i].depth;
    GsSortLine(&starfield,TheOT,1);
  }
}