#include <os.h>
#include "utils.h"
#include "rayhdr.h"
#define CAM_Z 2

asm(".string \"PRG\"\n");


int main(void) 
{
  int x, y, i;
  float a, b;
  //eye point
  float eye[] = {0, 0, 3};
  //list of centers in (x, y, z)
  float ctr[] = {0, 0, 0, 1, .3, 0};
  //list of radii
  float r[] = {1, .5};
  //list of colors
  float clr[] = {12, 8};
  //number of spheres
  float num = 2;
  //z-coordinate of the floor
  float floorz = -1;
  //coordinates of lamp
  float lamp[] = {1, 1, 1};
  clearScreen();
  for (x = 0; x < 320; x++) {
    for (y = 0; y < 240; y++) {
      a = (x - 160) / 80.0;
      b = (y - 120) / 80.0; 
      float vd[] = {a - eye[0], b - eye[1], -1};
      float t = 1000;
      int sphr_idx = -1;
      for (i = 0; i < num; i++) {
        float thisctr[] = {ctr[3 * i], ctr[3 * i + 1], ctr[3 * i + 2]};
        float this_inter = raysphere(eye, vd, thisctr, r[i]);
        if (this_inter > 0 && this_inter < t) {
          t = this_inter;
          sphr_idx = i;
        }   
      }
      float this_inter = rayxyplane(eye, vd, floorz);
      if (this_inter > 0 && this_inter < t) {
        t = this_inter;
        sphr_idx = -2;
      }

      float mlt = 1;
      
      if (sphr_idx < -2) goto black;
      float pt[] = {eye[0] + t * vd[0], eye[1] + t * vd[1], eye[2] + t * vd[2]};
      float ldir[] = {pt[0] - lamp[0], pt[1] - lamp[1], pt[2] - lamp[2]};
      int blocked = 0;
      for (i = 0; i < num; i++) {
        float thisctr[] = {ctr[3 * i], ctr[3 * i + 1], ctr[3 * i + 2]};
        float this_inter = raysphere(lamp, ldir, thisctr, r[i]);
        if (this_inter > 0 && i != sphr_idx) {
          blocked = 1;
          break;
        }   
      }
      if (blocked) mlt = 0.3;

      if (sphr_idx >= 0) {
        float thectr[] = {ctr[3 * sphr_idx], ctr[3 * sphr_idx + 1], ctr[3 * sphr_idx + 2]};
        float nrml[] = {thectr[0] - pt[0], thectr[1] - pt[1], thectr[2] - pt[2]};
        float cos = angle(nrml, ldir);
        if (cos < 0) {
          cos = 0;
        } 
        setPixel(x, y, (int) (cos * clr[sphr_idx] * mlt));
      } else if (sphr_idx == -2) {
        float color = 15;
        //checkers on floor
        if (pt[0] * pt[1] >= 0 && ((int) fabs(pt[0]) % 2 == 0 && (int) fabs(pt[1]) % 2 == 1 ||
            (int) fabs(pt[0]) % 2 == 1 && (int) fabs(pt[1]) % 2 == 0)) color = 0;
        if (pt[0] * pt[1] < 0 && ((int) fabs(pt[0]) % 2 == 1 && (int) fabs(pt[1]) % 2 == 1 ||
            (int) fabs(pt[0]) % 2 == 0 && (int) fabs(pt[1]) % 2 == 0)) color = 0;
        //end checkers
        float nrml[] = {0, 0, -1};
        float cos = angle(nrml, ldir);
        if (cos < 0) {
          cos = 0;
        } 
        setPixel(x, y, (int) (cos * color * mlt));
      } else {
        black:
        setPixel(x, y, 0);
      }
    }
  }
  while(!isKeyPressed(KEY_NSPIRE_ESC)); 
  return 0;
}