// 3D Engine
//
// Vector with components (x, y, z, w).
//
// Author  Matthew Caryl
// Created 4.5.97
//
//  Although under copywrite to the author (Matthew Caryl) this code can be copied and modified for non-commercial
//  purposes as long as any derivatives contain this condition.

package ADT;

import java.lang.Math;

public class Vector {
	//
	// Public interface
	//
	
	public float x, y, z, w;
	
	public Vector(float X, float Y, float Z) {
		set(X, Y, Z);
		}
	
	public Vector() {
		set(0f, 0f, 0f);
		}
	
	public Vector(Vector v) {
		set(v);
		}
	
	public void set(float X, float Y, float Z) {
		x = X;
		y = Y;
		z = Z;
		w = 1f;
		}
	
	public void set(Vector v) {
		x = v.x;
		y = v.y;
		z = v.z;
		w = v.w;
		}
	
	public void normalise() {
		float m = (float) Math.sqrt(x * x + y * y + z * z);
		
		if (m != 0f) {
			x /= m;
			y /= m;
			z /= m;
			w = 1f;
			}
		}
/*
	public void renormalise() {
		if (w != 0f) {
			x /= w;
			y /= w;
			z /= w;
			w = 1f;
			}
		else
			set(0f, 0f, 0f);
		}
*/
	public void renormalise() {
		if (w > 0f) {
			x /= w;
			y /= w;
			z /= w;
			w = 1f;
			}
		else if (w < 0f) {
			x /= -w;
			y /= -w;
			z /= -w;
			w = 1f;
			}
		else
			set(0f, 0f, 0f);
		}
	
	public void subtract(Vector v) {
		x -= v.x;
		y -= v.y;
		z -= v.z;
		w -= v.w;
		}
	
	public float dot(Vector v) {
		return x * v.x + y * v.y + z * v.z;
		}
	
	public void cross(Vector v) {
		float old_x = x;
		float old_y = y;
		float old_z = z;
		float old_w = w;
		
		x =  old_y * v.z - old_z * v.y;
		y = -old_x * v.z + old_z * v.x;
		z =  old_x * v.y - old_y * v.x;
		}
	}