package graphics;

public class Polyhedron extends Shape
{
  //half-space planes
  Plane[] planes;

  public Polyhedron(Plane[] planes)
  {
    this.planes = planes;
    this.matrix = new Matrix3D();
  }

  //returns array of t values (roots) or void if no intersection
  //sets point of intersection and normal there
  public double[] testRay(Vector3 v, Vector3 w, Vector3 pos, Vector3 normal)
  {
    if (planes == null || planes.length == 0)
    {
      System.err.println("Warning - null or empty set of planes for Polyhedron!");
      return null;
    }

    //indices of intersection planes
    int enterPlane = -1, exitPlane = -1;

    //t values of each plane
    double[] planeRoots = new double[planes.length];

    //keep track of what the normal of each plane is
    Vector3[] planeNormals = new Vector3[planes.length];

    double t;

    //want max enter, min exit
    double tEnter = Double.NEGATIVE_INFINITY, tExit = Double.POSITIVE_INFINITY;
    for (int i = 0; i<planes.length; i++)
    {
//System.err.println("testing plane #" + (i+1));

      //which side of plane is V on?
      double orientation = planes[i].equation(v);

      planeNormals[i] = new Vector3();
      double[] tmp = planes[i].testRay(v, w, pos, planeNormals[i]);

      //it missed this particular plane
      if (tmp == null) continue;

      t = planeRoots[i] = tmp[0];
//System.err.println("t = " + t);
//System.err.println("hit: " + pos);
//System.err.println("orientation = " + orientation);

      if (t <= 0.001)
      {
        //return null;
        //continue;

        if (orientation > 0) return null;
        else t = Double.POSITIVE_INFINITY;
      }

      if (orientation > 0 && t > tEnter) //entering plane
      {
        tEnter = t;
        enterPlane = i; //enter plane is current plane
      }

      if (orientation < 0 && t < tExit) //exiting plane
      {
        tExit = t;
        exitPlane = i; //exit plane is current plane
      }
    }
//System.err.println("tEnter = " + tEnter);
//System.err.println("tExit = " + tExit);

    //no intersection if there's no enter plane or exit plane
    if (enterPlane < 0 || exitPlane < 0) return null;

    //no intersection if tEnter > tExit
    if (tEnter > tExit) return null;

    //calculate intersection point and normal
    setIntersectionPoint(v, w, tEnter, pos);
    normal.copy(planeNormals[enterPlane]);

    double[] roots = new double[2];
    roots[0] = planeRoots[enterPlane];
    roots[1] = planeRoots[exitPlane];

    return roots;
  }

  //transformation of polyhedron = transformation of planes
  public void transform()
  {
    if (this.matrix == null)
    {
      System.err.println("Warning: transformation matrix is null.  Cannot transform Polyhedron.");
      return;
    }

    for (int i = 0; i<planes.length; i++)
    {
      planes[i].matrix = this.matrix;
      planes[i].transform();
    }
  }

  public Polyhedron deepCopy()
  {
    Plane[] newPlanes = new Plane[this.planes.length];

    for (int i=0; i<planes.length; i++)
      newPlanes[i] = this.planes[i].deepCopy();

    return new Polyhedron(newPlanes);
  }

  public String toString()
  {
    String s = "";
    for (int i=0; i<planes.length; i++)
      s += planes[i].toString() + "\n";
    return s;
  }
}