/*
 * Pixel Dungeon
 * Copyright (C) 2012-2015  Oleg Dolya
 *
 * Shattered Pixel Dungeon
 * Copyright (C) 2014-2016 Evan Debenham
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

package com.watabou.glwrap;

public class Matrix {

	public static final float G2RAD = 0.01745329251994329576923690768489f;
	
	public static float[] clone( float[] m ) {
		
		int n = m.length;
		float[] res = new float[n];
		do {
			res[--n] = m[n];
		} while (n > 0);
		
		return res;
	}
	
	public static void copy( float[] src, float[] dst ) {
		
		int n = src.length;
		do {
			dst[--n] = src[n];
		} while (n > 0);

	}

	private static float[] identity = new float[]{
			1, 0, 0, 0,
			0, 1, 0, 0,
			0, 0, 1, 0,
			0, 0, 0, 1
	};
	
	public static void setIdentity( float[] m ) {
		System.arraycopy(identity, 0, m, 0, identity.length);
	}

	public static void rotate( float[] m, float a ) {
		a *= G2RAD;
		float sin = (float)Math.sin( a );
		float cos = (float)Math.cos( a );
		float m0 = m[0];
		float m1 = m[1];
		float m4 = m[4];
		float m5 = m[5];
		m[0] = m0 * cos + m4 * sin;
		m[1] = m1 * cos + m5 * sin;
		m[4] = -m0 * sin + m4 * cos;
		m[5] = -m1 * sin + m5 * cos;
	}
	
	public static void skewX( float[] m, float a ) {
		double t = Math.tan( a * G2RAD );
		m[4] += -m[0] * t;
		m[5] += -m[1] * t;
	}
	
	public static void skewY( float[] m, float a ) {
		double t = Math.tan( a * G2RAD );
		m[0] += m[4] * t;
		m[1] += m[5] * t;
	}
	
	public static void scale( float[] m, float x, float y ) {
		m[0] *= x;
		m[1] *= x;
		m[2] *= x;
		m[3] *= x;
		m[4] *= y;
		m[5] *= y;
		m[6] *= y;
		m[7] *= y;
	//	android.opengl.Matrix.scaleM( m, 0, x, y, 1 );
	}
	
	public static void translate( float[] m, float x, float y ) {
		m[12] += m[0] * x + m[4] * y;
		m[13] += m[1] * x + m[5] * y;
	}
	
	public static void multiply( float[] left, float right[], float[] result ) {
		android.opengl.Matrix.multiplyMM( result, 0, left, 0, right, 0 );
	}
}