/*

 * C++ RayTracer

 * file: scene.cc

 *

 * Radek Brich, 2006

 */

#include <math.h>

#include "common.h"

#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

	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();

}

{

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

}

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

{

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

	{

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

			/* ray is parallel to these planes */

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

				return false;

		} else

		{

			/* compute the intersection distance of the planes */

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

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

				return false; /* box missed */

			if (tfar < 0)

				return false; /* box is behind ray */

		}

	}

	a = tnear;

	b = tfar;

	return true;

}

{

	Vector3 V = ray.o - center;

	if (Det > 0) {

		d -= sqrtf(Det);

		if (d > 0 && d < dist)

		{

			dist = d;

			return true;

		}

	}

	return false;

}

{

	Vector3 V = ((Ray)ray).o - center;

	if (Det > 0) {

		Det = sqrtf(Det);

		if (t1 < 0)

		{

			if (t2 > 0)

			{

				// ray from inside of the sphere

				allts.push_back(0.0);

				allts.push_back(t2);

				return true;

			}

			else

				return false;

		}

		else

		{

			allts.push_back(t1);

			allts.push_back(t2);

			return true;

		}

	}

	return false;

}

BBox Sphere::get_bbox()

{

	BBox bbox = BBox();

	bbox.L = center - radius;

	bbox.H = center + radius;

	return bbox;

}

{

	bool res = get_bbox().intersect(ray, a, b);

	if (res && a < dist)

	{

		dist = a;

		return true;

	}

	else

		return false;

}

Vector3 Box::normal(Vector3 &P)

{

	Vector3 N;

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

	{

		if (P.cell[i] >= L.cell[i]-Eps && P.cell[i] <= L.cell[i]+Eps)

		//if (P.cell[i] == L.cell[i])

		{

			N.cell[i] = -1.0;

			break;

		}

		if (P.cell[i] >= H.cell[i]-Eps && P.cell[i] <= H.cell[i]+Eps)

		//if (P.cell[i] == H.cell[i])

		{

			N.cell[i] = +1.0;

			break;

		}

	}

	return N;

}

// this initialization and following intersection methods implements

// Fast Triangle Intersection algorithm from

// http://www.mpi-inf.mpg.de/~wald/PhD/

Triangle::Triangle(const Vector3 &aA, const Vector3 &aB, const Vector3 &aC, Material *amaterial)

	: A(aA), B(aB), C(aC)

{

	material = amaterial;

	Vector3 c = B - A;

	Vector3 b = C - A;

	N = cross(c, b);

	if (fabsf(N.x) > fabsf(N.y))

	{

		if (fabsf(N.x) > fabsf(N.z))

			k = 0;

		else

			k = 2;

	}

	else

	{

		if (fabsf(N.y) > fabsf(N.z))

			k = 1;

		else

			k = 2;

	}

	int u = (k + 1) % 3;

	int v = (k + 2) % 3;

	nu = N[u] * krec;

	nv = N[v] * krec;

	nd = dot(N, A) * krec;

	// first line equation

	bnu = b[u] * reci;

	bnv = -b[v] * reci;

	// second line equation

	cnu = c[v] * reci;

	cnv = -c[u] * reci;

	// finalize normal

	N.normalize();

}

// see comment for previous method

{

	Vector3 O = ray.o;

	Vector3 D = ray.dir;

	const int modulo3[5] = {0,1,2,0,1};

	const int ku = modulo3[k+1];

	const int kv = modulo3[k+2];

	if (!(t < dist && t > 0))

		return false;

	if (beta < 0)

		return false;

	if (gamma < 0)

		return false;

	if ((beta + gamma) > 1)

		return false;

	dist = t;

	return true;

}

BBox Triangle::get_bbox()

{

	BBox bbox = BBox();

	bbox.L = A;

	if (B.x < bbox.L.x)  bbox.L.x = B.x;

	if (C.x < bbox.L.x)  bbox.L.x = C.x;

	if (B.y < bbox.L.y)  bbox.L.y = B.y;

	if (C.y < bbox.L.y)  bbox.L.y = C.y;

	if (B.z < bbox.L.z)  bbox.L.z = B.z;

	if (C.z < bbox.L.z)  bbox.L.z = C.z;

	bbox.H = A;

	if (B.x > bbox.H.x)  bbox.H.x = B.x;

	if (C.x > bbox.H.x)  bbox.H.x = C.x;

	if (B.y > bbox.H.y)  bbox.H.y = B.y;

	if (C.y > bbox.H.y)  bbox.H.y = C.y;

	if (B.z > bbox.H.z)  bbox.H.z = B.z;

	if (C.z > bbox.H.z)  bbox.H.z = C.z;

	return bbox;

};