/*
 * Pixel Dungeon
 * Copyright (C) 2012-2015 Oleg Dolya
 *
 * Shattered Pixel Dungeon
 * Copyright (C) 2014-2023 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;
	}
	
	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 ) {
		final float ax1 = left[0];
		final float ay1 = left[1];
		final float az1 = left[2];
		final float aw1 = left[3];
		
		final float ax2 = left[4];
		final float ay2 = left[5];
		final float az2 = left[6];
		final float aw2 = left[7];
		
		final float ax3 = left[8];
		final float ay3 = left[9];
		final float az3 = left[10];
		final float aw3 = left[11];
		
		final float ax4 = left[12];
		final float ay4 = left[13];
		final float az4 = left[14];
		final float aw4 = left[15];
		
		final float bx1 = right[0];
		final float by1 = right[1];
		final float bz1 = right[2];
		final float bw1 = right[3];
		
		final float bx2 = right[4];
		final float by2 = right[5];
		final float bz2 = right[6];
		final float bw2 = right[7];
		
		final float bx3 = right[8];
		final float by3 = right[9];
		final float bz3 = right[10];
		final float bw3 = right[11];
		
		final float bx4 = right[12];
		final float by4 = right[13];
		final float bz4 = right[14];
		final float bw4 = right[15];
		
		result[0] = ax1 * bx1 + ax2 * by1 + ax3 * bz1 + ax4 * bw1;
		result[1] = ay1 * bx1 + ay2 * by1 + ay3 * bz1 + ay4 * bw1;
		result[2] = az1 * bx1 + az2 * by1 + az3 * bz1 + az4 * bw1;
		result[3] = aw1 * bx1 + aw2 * by1 + aw3 * bz1 + aw4 * bw1;
		
		result[4] = ax1 * bx2 + ax2 * by2 + ax3 * bz2 + ax4 * bw2;
		result[5] = ay1 * bx2 + ay2 * by2 + ay3 * bz2 + ay4 * bw2;
		result[6] = az1 * bx2 + az2 * by2 + az3 * bz2 + az4 * bw2;
		result[7] = aw1 * bx2 + aw2 * by2 + aw3 * bz2 + aw4 * bw2;
		
		result[8] = ax1 * bx3 + ax2 * by3 + ax3 * bz3 + ax4 * bw3;
		result[9] = ay1 * bx3 + ay2 * by3 + ay3 * bz3 + ay4 * bw3;
		result[10] = az1 * bx3 + az2 * by3 + az3 * bz3 + az4 * bw3;
		result[11] = aw1 * bx3 + aw2 * by3 + aw3 * bz3 + aw4 * bw3;
		
		result[12] = ax1 * bx4 + ax2 * by4 + ax3 * bz4 + ax4 * bw4;
		result[13] = ay1 * bx4 + ay2 * by4 + ay3 * bz4 + ay4 * bw4;
		result[14] = az1 * bx4 + az2 * by4 + az3 * bz4 + az4 * bw4;
		result[15] = aw1 * bx4 + aw2 * by4 + aw3 * bz4 + aw4 * bw4;
	}
}