/* Matrix3D.java
 * 
 * Class that implements and contains a 4x4 Matrix
 * 
 */

public class Matrix3D {

	double matrix[][] = new double[4][4];

	public Matrix3D() {
		identity();
	}

	/* transform(double[])
	 * returns array with 3 values representing the
	 * src point transformed by the matrix
	 */
	public double[] transform(double src[]) {

		double dst[] = new double[3];

		dst[0] =
			matrix[0][0] * src[0]
				+ matrix[0][1] * src[1]
				+ matrix[0][2] * src[2]
				+ matrix[0][3];
		dst[1] =
			matrix[1][0] * src[0]
				+ matrix[1][1] * src[1]
				+ matrix[1][2] * src[2]
				+ matrix[1][3];
		dst[2] =
			matrix[2][0] * src[0]
				+ matrix[2][1] * src[1]
				+ matrix[2][2] * src[2]
				+ matrix[2][3];

		return dst;
	}

	/* multiply(Matrix3D)
	 * Set matrix to the result of multiplying this.matrix by
	 * the Matrix3D.matrix passed in
	 */
	public void multiply(Matrix3D a) {
		Matrix3D myCopy = new Matrix3D();

		myCopy.copy(this); // FIRST COPY TO A TEMPORARY MATRIX
		for (int i = 0; i < 4; i++)
			for (int j = 0; j < 4; j++) {
				double sum = 0;
				for (int k = 0; k < 4; k++)
					sum += myCopy.get(i, k) * a.get(k, j);
				matrix[i][j] = sum;
			}
	}

	/* translate (double,double,double)
	 * Translate matrix by (a,b,c)
	 */
	public void translate(double a, double b, double c) {
		Matrix3D temp = new Matrix3D();
		temp.translationMatrix(a, b, c); // CREATE A TRANSLATION MATRIX
		multiply(temp); // MULTIPLY BY THAT MATRIX
	}

	/* scale(double,double,double)
	 * Scale matrix by (a, b, c)
	 */
	public void scale(double a, double b, double c) {
		Matrix3D temp = new Matrix3D();
		temp.scaleMatrix(a, b, c);
		multiply(temp);
	}

	/* rotateX(double)
	 * Rotate matrix by (theta) radians
	 */
	public void rotateX(double theta) {
		Matrix3D temp = new Matrix3D();
		temp.rotateXMatrix(theta);
		multiply(temp);
	}

	/* rotateY(double)
	 * Rotate matrix by (theta) radians
	 */
	public void rotateY(double theta) {
		Matrix3D temp = new Matrix3D();
		temp.rotateYMatrix(theta);
		multiply(temp);
	}

	/* rotateZ(double)
	 * Rotate matrix by (theta) radians
	 */
	public void rotateZ(double theta) {
		Matrix3D temp = new Matrix3D();
		temp.rotateZMatrix(theta);
		multiply(temp);
	}
	
	/* prints the matrix - for error cheking */
	public void printMatrix() {
		System.out.print("\n");
		for (int i = 0; i < matrix.length; i++) {
			System.out.print("\n");
			for (int j=0; j < matrix[i].length; j++)
				System.out.print("(" + matrix[i][j] + ")");
		}
		System.out.print("\n");
	}

	/* rotateXMatrix(double)
	 * Set matrix to rotate theta radians round x axis
	 */
	private void rotateXMatrix(double theta) {
		identity();
		set(1, 1, Math.cos(theta));
		set(1, 2, - (Math.sin(theta)));
		set(2, 1, Math.sin(theta));
		set(2, 2, Math.cos(theta));
	}

	/* rotateYMatrix(double)
	 * Set matrix to rotate theta radians round Y axis
	 */
	private void rotateYMatrix(double theta) {
		identity();
		set(0, 0, Math.cos(theta));
		set(0, 2, Math.sin(theta));
		set(2, 0, - (Math.sin(theta)));
		set(2, 2, Math.cos(theta));
	}

	/* rotateZMatrix(double)
	 * Set matrix to rotate theta radians round Z axis
	 */
	private void rotateZMatrix(double theta) {
		identity();
		set(0, 0, Math.cos(theta));
		set(0, 1, - (Math.sin(theta)));
		set(1, 0, Math.sin(theta));
		set(1, 1, Math.cos(theta));
	}

	/* copy(Matrix3D)
	 * Copies other matrix into this.matrix
	 */
	public void copy(Matrix3D src) {
		for (int i = 0; i < 4; i++)
			for (int j = 0; j < 4; j++)
				set(i, j, src.get(i, j));
	}

	/* identity()
	 * sets matrix to the identity matrix
	 */
	public void identity() {
		// set each (i,j) to 0
		// unless i==j, then set to 1
		for (int i = 0; i < 4; i++)
			for (int j = 0; j < 4; j++)
				set(i, j, (i == j) ? 1 : 0);
	}

	/* set(int,int,double)
	 * Sets matrix[i][j] to value
	 */
	private void set(int i, int j, double value) {
		matrix[i][j] = value;
	}

	/* get(int,int)
	 * Returns value of matrix[i][j]
	 */
	public double get(int i, int j) {
		return matrix[i][j];
	}

	/* translationMatrix(double,double,double)
	 * Sets matrix to translation that would 
	 * move x, y, z by a, b, c
	 */
	private void translationMatrix(double a, double b, double c) {
		identity();
		set(0, 3, a);
		set(1, 3, b);
		set(2, 3, c);
	}

	/* scaleMatrix(double,double,double)
	 * Sets matrix to scaling matrix to scale
	 * x, y, z by a, b, c
	 */
	private void scaleMatrix(double a, double b, double c) {
		identity();
		set(0, 0, a);
		set(1, 1, b);
		set(2, 2, c);
	}
}