#include "particle.hpp"
#include "polygon.hpp"

void
ParticleEngineCreate(ParticleEngine* pe, int n, float x, float y, float z)
{
   memset(pe, 0, sizeof(ParticleEngine));

   VectorCreate(pe->origin, x, y, z);
   
   pe->n    = n;
   pe->life = (int*)   calloc(n, sizeof(int));
   pe->pos  = (Vector*) calloc(n, sizeof(Vector));
   pe->vel  = (Vector*) calloc(n, sizeof(Vector));   

   assert(pe->life && pe->pos && pe->vel);
}

void
ParticleEngineUpdate(ParticleEngine* pe)
{
   for (int i = 0; i < pe->n; i++)
   {
      if (pe->life[i] == 0)
      {
         pe->life[i] = rand() % 1000;

         v3dcpy(pe->pos[i], pe->origin);
         VectorCreate(pe->vel[i],
          (rand() % 100 - 50) / 100.0f,
          (rand() % 100 - 50) / 100.0f,
          (rand() % 100 - 50) / 100.0f);
      }
      else
      {
         pe->life[i]--;
      }
      VectorAddition(pe->pos[i], pe->pos[i], pe->vel[i]);
      pe->vel[i][1] -= 0.001f;
   }
}

void
ParticleEngineRender(ParticleEngine* pe, Camera* camera)
{
   Vector   tmp[1000];
   Pixel**  fb;
   Pixel**  zb;
   unsigned x, y, z, width, height;

   width  = camera->fb->width;
   height = camera->fb->height;
   fb     = camera->fb->pixels;
   zb     = camera->zb->pixels;
   
   PolygonTransform(tmp, pe->pos, pe->n, camera->matrix);

   PolygonProject(tmp, pe->n, camera);

   for (int i = 0; i < pe->n; i++)
   {
      z = Round(tmp[i][2]);
      
      if (z > 0)
      {
         x = Round(tmp[i][0]);
         y = Round(tmp[i][1]);

         if (x < width && y < height && z < zb[y][x])
         {
            fb[y][x] = PIXEL_GREEN;
         }
      }
   }
}