/*

 * scene.cc: classes for objects in scene

 *

 * This file is part of Pyrit Ray Tracer.

 *

 * Copyright 2006, 2007, 2008  Radek Brich

 *

 * 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.

 */

#include "scene.h"

void Camera::rotate(const Quaternion &q)

{

	/*

	//non-optimized

	Quaternion res;

	res = q * Quaternion(u) * conjugate(q);

	u = res.toVector();

	res = q * Quaternion(v) * conjugate(q);

	v = res.toVector();

	res = q * Quaternion(p) * conjugate(q);

	p = res.toVector();

	*/

	// optimized

	Float t2 =   q.a*q.b;

	Float t3 =   q.a*q.c;

	Float t4 =   q.a*q.d;

	Float t5 =  -q.b*q.b;

	Float t6 =   q.b*q.c;

	Float t7 =   q.b*q.d;

	Float t8 =  -q.c*q.c;

	Float t9 =   q.c*q.d;

	Float t10 = -q.d*q.d;

	Float x,y,z;

	x = 2*( (t8 + t10)*p.x + (t6 -  t4)*p.y + (t3 + t7)*p.z ) + p.x;

	y = 2*( (t4 +  t6)*p.x + (t5 + t10)*p.y + (t9 - t2)*p.z ) + p.y;

	z = 2*( (t7 -  t3)*p.x + (t2 +  t9)*p.y + (t5 + t8)*p.z ) + p.z;

	p = Vector3(x,y,z);

	x = 2*( (t8 + t10)*u.x + (t6 -  t4)*u.y + (t3 + t7)*u.z ) + u.x;

	y = 2*( (t4 +  t6)*u.x + (t5 + t10)*u.y + (t9 - t2)*u.z ) + u.y;

	z = 2*( (t7 -  t3)*u.x + (t2 +  t9)*u.y + (t5 + t8)*u.z ) + u.z;

	u = Vector3(x,y,z);

	x = 2*( (t8 + t10)*v.x + (t6 -  t4)*v.y + (t3 + t7)*v.z ) + v.x;

	y = 2*( (t4 +  t6)*v.x + (t5 + t10)*v.y + (t9 - t2)*v.z ) + v.y;

	z = 2*( (t7 -  t3)*v.x + (t2 +  t9)*v.y + (t5 + t8)*v.z ) + v.z;

	v = Vector3(x,y,z);

	p.normalize();

	u.normalize();

	v.normalize();

}

void Camera::move(const Float fw, const Float left, const Float up)

{

	eye = eye + fw*p + left*u + up*v;

}

/* http://www.siggraph.org/education/materials/HyperGraph/raytrace/rtinter3.htm */

bool BBox::intersect(const Ray &ray, Float &a, Float &b)

{

	register Float tnear = -Inf;

	register Float tfar = Inf;

	register Float t1, t2;

	for (int i = 0; i < 3; i++)

	{

		if (ray.dir[i] == 0) {

			/* ray is parallel to these planes */

			if (ray.o[i] < L[i] || ray.o[i] > H[i])

				return false;

		} else

		{

			/* compute the intersection distance of the planes */

			t1 = (L[i] - ray.o[i]) / ray.dir[i];

			t2 = (H[i] - ray.o[i]) / ray.dir[i];

			if (t1 > t2)

				swap(t1, t2);

			if (t1 > tnear)

				tnear = t1; /* want largest Tnear */

			if (t2 < tfar)

				tfar = t2; /* want smallest Tfar */

			if (tnear > tfar || tfar < 0)

				return false; /* box missed; box is behind ray */

		}

	}

	a = tnear;

	b = tfar;

	return true;

}