package graphics;

public class Sphere {
  public Vector3 center;
  public double radius;
  //public int[] color = {0, 0, 0};

  //shape's colors
  private double shininess;
  private int[] diffuseColor = {0,0,0};
  private int[] specularColor = {0,0,0};

  public void setDiffuse(int r, int g, int b)
  {
    diffuseColor[0] = r; diffuseColor[1] = g; diffuseColor[2] = b;
  }

  public void setSpecular(double s, int r, int g, int b)
  {
    shininess = s;
    specularColor[0] = r; specularColor[1] = g; specularColor[2] = b;
  }

  //takes a surface coordinate, array of lights, ambient component, and
  //returns color
  public int[] shade(double[] pos, Light[] lights, int[] ambient)
  {
    double nx = pos[0] - center.get(0), ny = pos[1] - center.get(1),  nz = pos[2] - center.get(2);

    Vector3 eye = new Vector3(0, 0, 1); //eye/camera is at the origin looking at neg z
    //eye.normalize();
    Vector3 normal = new Vector3(nx, ny, nz);
    normal.normalize();
    //normal.scale(-1);

//System.err.println("in shade()");
//System.err.println(nx+","+ny+","+nz);

    double r = 0, g = 0, b = 0;

    for (int li = 0; li < lights.length; li++)
    {
      //colors for this light
      double lr = 0, lg = 0, lb = 0;

      //diffuse shading
      // f is L dot N
      double fDiff = normal.dotProduct( lights[li].getDirectionVector() );
      if (fDiff < 0) fDiff = 0;
//System.err.println("fDiff = " + fDiff);

      lr += fDiff * diffuseColor[0];
      lg += fDiff * diffuseColor[1];
      lb += fDiff * diffuseColor[2];

      //specular shading
      //R = 2*f*N - L
      //Ls = [rs,gs,bs]max(0, E ∙ R)^p
      Vector3 R = new Vector3(normal); //copy normal vector
      R.scale(-2 * fDiff); // r is now -2fN
      R.add( lights[li].getDirectionVector() ); //r is now L - 2fN
      R.scale(-1);
      R.normalize();

      double fSpec = Math.pow(eye.dotProduct(R), shininess); //E ∙ R
      if (fSpec < 0) fSpec = 0;
//System.err.println("fSpec = " + fSpec);

      lr += fSpec * specularColor[0];
      lg += fSpec * specularColor[1];
      lb += fSpec * specularColor[2];

      //factor in light source, but
      //scale back down (compare 0.5 * 0.5 with (128 * 128)/256)
      lr *= lights[li].color[0] / 256.0;
      lg *= lights[li].color[1] / 256.0;
      lb *= lights[li].color[2] / 256.0;

      //add the light to object's light
      r += lr; g += lg; b += lb;
    }

    //add ambient component
    r += ambient[0]; g += ambient[1]; b += ambient[2];

    if (r > 255) r = 255; if (g > 255) g = 255; if (b > 255) b = 255;

//System.err.println(r+","+g+","+b);

    int[] rgb = {0,0,0};

    //copy color info back into shape
    rgb[0] = (int)r; rgb[1] = (int)g; rgb[2] = (int)b;
//System.err.println(rgb[0]+","+rgb[1]+","+rgb[2]);
    return rgb;
  }
}