/******************************************************************************
 * The MIT License (MIT)
 * 
 * Copyright (c) 2014 Crytek
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 ******************************************************************************/


#pragma once

#include <math.h>
#include "vec.h"
#include "matrix.h"

class Quatf
{
	public:
		float w;
		Vec3f v;

		static Quatf AxisAngle(Vec3f axis, float angle)
		{
			Quatf q;

			q.w = cosf(angle/2.0f);
			q.v.x = axis.x * sinf(angle/2.0f);
			q.v.y = axis.y * sinf(angle/2.0f);
			q.v.z = axis.z * sinf(angle/2.0f);

			return q;
		}

		Matrix4f GetMatrix()
		{
			float q0 = w;
			float q1 = v.x;
			float q2 = v.y;
			float q3 = v.z;

			float m[16] = { 1.0f - 2*(q2*q2 + q3*q3), 2.0f*(q1*q2 - q0*q3), 2.0f*(q0*q2 + q1*q3), 0.0f,
							2.0f*(q1*q2 + q0*q3), 1.0f - 2*(q1*q1 + q3*q3), 2.0f*(q2*q3 - q0*q1), 0.0f,
							2.0f*(q1*q3 - q0*q2), 2.0f*(q0*q1 + q2*q3), 1.0f - 2*(q1*q1 + q2*q2), 0.0f,
							0.0f, 0.0f, 0.0f, 1.0f,
			};

			return Matrix4f(m);
		}
};

inline Quatf operator *(const Quatf &a, const Quatf &b)
{
	Quatf r;

	r.w = a.w * b.w - a.v.Dot(b.v);
	r.v = b.v * a.w + a.v * b.w + a.v.Cross(b.v);

	return r;
}
