public class sphere{

	double[] center;
	double R;
	material m;
	double[] toCenter;
	static double[] e=new double[] {0,0,1};//simplifying by assuming the eye is infinitely remote

	public sphere(){
		center=new double[] {0,0,-5};
		R=0.8;
		m=new material();
	}

	public sphere(double r, material ms, double x, double y, double z){
		center=new double[3];
		center[0]=x;
		center[1]=y;
		center[2]=z;
		m = new material();
		m.copy(ms);
		R=r;
	}

	public double intersect(double[] v, double[] w){
		double A=dotP(w,w);
		toCenter=diff(v,center);
		double B=2*dotP(toCenter,w);
		double C=dotP(toCenter,toCenter) - R*R;
		double discr=B*B-4*A*C;
		if (discr<0) return 10500;
		if (discr==0) return -B/(2*A);
		if (discr>0) return (-B+Math.sqrt(discr))/(2*A);
		
		return 10500;
	}

	public double[] shade(light[] lights, double[] v, double[] w, double t){

		double[] res = new double[] {0,0,0};
		double[] currPt=new double[3];
		for (int i=0; i<3; ++i){
			currPt[i]=v[i]+t*w[i];
			res[i]=m.ambient[i];
		}
		double[] normV=diff(currPt, center);
		normV=normalize(normV);	
		if (lights!=null){
			for (int i=0; i<lights.length;i++){
				for (int j=0;j<3;j++){
					//double vald=lights[i].dir[0]*normV[0]+lights[i].dir[1]*normV[1]+lights[i].dir[2]*normV[2];	
					double vald=dotP(lights[i].dir, normV);
					if (vald>0)
						res[j]+=lights[i].rgb[j]*m.diffuse[j]*vald;// diffuse


					double[] tmp=new double[3];
					for (int k=0; k<3; ++k)
						tmp[k]=2*vald*normV[k];

					double vals=dotP(diff(tmp,lights[i].dir),e);
					if (vals>0)
						res[j]+=lights[i].rgb[j]*m.specular[j]*Math.pow(vals,m.p);

				}


			}
		}
		return res;
	}

	public double dotP(double[] vs, double[] ws){
		double res=0;
		int n=vs.length;
		for (int i=0; i<n; ++i){
			res+=vs[i]*ws[i];
		}
		return res;
	}

	public double[] diff(double[] vs, double[] ws){
		int n=vs.length;
		double res[]=new double[n];
		for (int i=0; i<n; ++i){
			res[i]=vs[i]-ws[i];
		}
		return res;
	}	

	public double[] normalize(double[] vs){
		int n=vs.length;
		double norm=0;
		for (int i=0; i<n; ++i){
			norm+=vs[i]*vs[i];
		}
		double[] res=new double[n];
		if(norm!=0)
			for (int i=0; i<n; ++i){
				res[i]=vs[i]/Math.sqrt(norm);
			}
		return res;
	}




}