import java.awt.Color;
import Vertex3D;
import Matrix3D;
import Surface;
import ZRaster;

class EdgeEqn {
  public float A, B, C;
  public int flag;    

  public EdgeEqn(Vertex3D v0, Vertex3D v1)
  {
    A = v0.y - v1.y;
    B = v1.x - v0.x;
    C = -0.5f * (A*(v0.x + v1.x) + B*(v0.y + v1.y));

    flag = 0;
    if (A >= 0) flag += 8;
    if (B >= 0) flag += 1;
  }

  public void flip()
  {
    A = -A;
    B = -B;
    C = -C;
  }

  public float evaluate(int x, int y)
  {
    return (A*x + B*y + C);
  }
}

public class Triangle {
  private static Vertex3D vlist[];
  protected int v[];
  protected float r[], g[], b[];
  protected Surface surface;
  private boolean culled;
  private Vertex3D vert[];

  public Triangle()
  {
  }

  public Triangle(int v0, int v1, int v2)
  {
    v = new int[3];
    v[0] = v0;
    v[1] = v1;
    v[2] = v2;    
    r = new float[3];
    g = new float[3];
    b = new float[3];
    vert = new Vertex3D[3];
    vert[0] = new Vertex3D();
    vert[1] = new Vertex3D();
    vert[2] = new Vertex3D();
    scale = -1;
    culled = false;
  }
    
  public void setSurface(Surface s)
  {
    surface = s;
  }

  public Surface getSurface()
  {
    return surface;
  }

  public boolean isVisible()
  {
    return (!culled);
  }
    
    
  /*
    ... you'll need to modify the following two methods ...
    */
  public void Illuminate(Light l[], int lights, Point3D eye, boolean cull)
  {
    //start afresh, darkness
    for (int i = 0; i < 3; i++) {
      r[i] = 0;
      g[i] = 0;
      b[i] = 0;
    }

    Vertex3D t1 = new Vertex3D(vlist[v[1]].x-vlist[v[0]].x, vlist[v[1]].y-vlist[v[0]].y, vlist[v[1]].z-vlist[v[0]].z);
    Vertex3D t2 = new Vertex3D(vlist[v[2]].x-vlist[v[0]].x, vlist[v[2]].y-vlist[v[0]].y, vlist[v[2]].z-vlist[v[0]].z);
    Vertex3D  n = new Vertex3D(t1.y*t2.z - t1.z*t2.y,
			       t1.z*t2.x - t1.x*t2.z,
			       t1.x*t2.y - t1.y*t2.x);
    vlist[v[0]].setNormal(n.x, n.y, n.z);
    
    for (int j = 0; j < lights; j++)
      {
	if (l[j].lightType == Light.AMBIENT)
	  {
	    for (int i = 0; i < 3; i++) 
	      {
		r[i] += surface.r*l[j].ir*surface.ka;
		g[i] += surface.g*l[j].ig*surface.ka;
		b[i] += surface.b*l[j].ib*surface.ka;
	      }
	  }
	if (l[j].lightType == Light.DIRECTIONAL)
	  {
	    
	    for (int i = 0; i < 3; i++) 
	      {
		float nDotl = vlist[v[0]].nx*-l[j].x +  vlist[v[0]].ny*-l[j].y + vlist[v[0]].nz*-l[j].z;
		if (nDotl<0)
		  nDotl=0;
		
		
		if (cull){
		  // vector from eye to a vertex, since I am too lazy to calculate a centroid
		  Vertex3D vee = new Vertex3D(vlist[v[0]].x - eye.x,  vlist[v[0]].y - eye.y , vlist[v[0]].z-eye.z);
		  float nDotvee = vee.x*vlist[v[0]].nx + vee.y*vlist[v[0]].ny + vee.z*vlist[v[0]].nz;
		  if (nDotvee>0){
		    culled=true;
		  }
		  else{
		    culled=false;
		    }
		  
		  } 
		r[i] += surface.r*l[j].ir*surface.kd*nDotl;
		g[i] += surface.g*l[j].ig*surface.kd*nDotl;
		b[i] += surface.b*l[j].ib*surface.kd*nDotl;
	      }
	  }
      }
  }

  
  public void ClipAndDraw(ZRaster raster, Matrix3D project)
  {
    vert[0] = project.transform(vlist[v[0]]);
    vert[1] = project.transform(vlist[v[1]]);
    vert[2] = project.transform(vlist[v[2]]);
    Draw(raster);
  }
  
  public void setVertexList(Vertex3D list[])
  {
    vlist = list;
  }

  protected EdgeEqn edge[];
  protected float area;
  protected int xMin, xMax, yMin, yMax;
  protected float scale;
  private static byte sort[][] = {
    {0, 1}, {1, 2}, {0, 2}, {2, 0}, {2, 1}, {1, 0}
  };

  public void PlaneEqn(float eqn[], float p0, float p1, float p2)
  {
    float Ap, Bp, Cp;

    float sp0 = scale * p0;
    float sp1 = scale * p1;
    float sp2 = scale * p2;
    Ap = edge[0].A*sp2 + edge[1].A*sp0 + edge[2].A*sp1;
    Bp = edge[0].B*sp2 + edge[1].B*sp0 + edge[2].B*sp1;
    Cp = edge[0].C*sp2 + edge[1].C*sp0 + edge[2].C*sp1;
    eqn[0] = Ap;
    eqn[1] = Bp;
    eqn[2] = Ap*xMin + Bp*yMin + Cp;
  }

  protected boolean triangleSetup(Raster r)
  {
    if (edge == null) edge = new EdgeEqn[3];

    /*
      Compute the three edge equations
      */
    edge[0] = new EdgeEqn(vert[0], vert[1]);
    edge[1] = new EdgeEqn(vert[1], vert[2]);
    edge[2] = new EdgeEqn(vert[2], vert[0]);

    /*
      Trick #1: Orient edges so that the
      triangle's interior lies within all
      of their positive half-spaces.

      Assuring that the area is positive
      accomplishes this
      */
    area = edge[0].C + edge[1].C + edge[2].C;

    if (area == 0)
      return false;
            
    if (area < 0) {
      edge[0].flip();
      edge[1].flip();
      edge[2].flip();
      area = -area;
    }

    /*
      Trick #2: compute bounding box
      */
    int xflag = edge[0].flag + 2*edge[1].flag + 4*edge[2].flag;
    int yflag = (xflag >> 3) - 1;
    xflag = (xflag & 7) - 1;

    xMin = (int) (vert[sort[xflag][0]].x);
    xMax = (int) (vert[sort[xflag][1]].x + 1);
    yMin = (int) (vert[sort[yflag][1]].y);
    yMax = (int) (vert[sort[yflag][0]].y + 1);

    /*
      clip triangle's bounding box to raster
      */
    xMin = (xMin < 0) ? 0 : xMin;
    xMax = (xMax >= r.width) ? r.width - 1 : xMax;
    yMin = (yMin < 0) ? 0 : yMin;
    yMax = (yMax >= r.height) ? r.height - 1 : yMax;
    return true;
  }
    
  public void Draw(ZRaster raster)
  {
    float zPlane[] = new float[3];
    float rPlane[] = new float[3];
    float gPlane[] = new float[3];
    float bPlane[] = new float[3];

    if (!triangleSetup(raster)) return;
    scale = 1 / area;
    PlaneEqn(zPlane, vert[0].z, vert[1].z, vert[2].z);
    PlaneEqn(rPlane, r[0], r[1], r[2]);
    PlaneEqn(gPlane, g[0], g[1], g[2]);
    PlaneEqn(bPlane, b[0], b[1], b[2]);

    int x, y;
    float A0 = edge[0].A;        float B0 = edge[0].B;        float t0 = A0*xMin + B0*yMin + edge[0].C;
    float A1 = edge[1].A;        float B1 = edge[1].B;        float t1 = A1*xMin + B1*yMin + edge[1].C;
    float A2 = edge[2].A;        float B2 = edge[2].B;        float t2 = A2*xMin + B2*yMin + edge[2].C;
    float Az = zPlane[0];        float Bz = zPlane[1];        float tz = zPlane[2];
    float Ar = rPlane[0];        float Br = rPlane[1];        float tr = rPlane[2];
    float Ag = gPlane[0];        float Bg = gPlane[1];        float tg = gPlane[2];
    float Ab = bPlane[0];        float Bb = bPlane[1];        float tb = bPlane[2];

    yMin *= raster.width;
    yMax *= raster.width;

    /*
      .... scan convert triangle ....
      */
    for (y = yMin; y <= yMax; y += raster.width) {
      float e0 = t0;
      float e1 = t1;
      float e2 = t2;
      float r = tr;
      float g = tg;
      float b = tb;
      float z = tz;
      boolean beenInside = false;
      for (x = xMin; x <= xMax; x++) {
	if ((e0 >= 0) && (e1 >= 0) && (e2 >= 0)) {       // all 3 edges must be >= 0
	  int iz = (int) z;
	  if (iz <= raster.zbuff[y+x]) {
	    int pixr = (int) (255.0f*r);
	    int pixg = (int) (255.0f*g);
	    int pixb = (int) (255.0f*b);
	    pixr = ((pixr & ~255) == 0) ? pixr << 16 : ((r < 0)     ? 0 : 255<<16);
	    pixg = ((pixg & ~255) == 0) ? pixg << 8  : ((g < 0)     ? 0 : 255<<8);
	    pixb = ((pixb & ~255) == 0) ? pixb       : ((b < 0)     ? 0 : 255);
	    raster.pixel[y+x] = (0xff000000 | pixr | pixg | pixb);
	    raster.zbuff[y+x] = iz;
	  }
	  beenInside = true;
	} else if (beenInside) break;
	e0 += A0;   e1 += A1;   e2 += A2;
	z += Az;    r += Ar;    g += Ag;    b += Ab;
      }
      t0 += B0;   t1 += B1;   t2 += B2;
      tz += Bz;   tr += Br;   tg += Bg;   tb += Bb;
    }
  }
}