/*

 * Pyrit Ray Tracer

 * file: scene.cc

 *

 * Radek Brich, 2006-2007

 */

#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

	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)

{

	Float tnear = -FLT_MAX;

	Float tfar = FLT_MAX;

	Float t1, t2;

	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;

}

bool Sphere::intersect(const Ray &ray, Float &dist) const

{

	Vector3 V = ray.o - center;

	register Float d = -dot(V, ray.dir);

	register Float Det = d * d - (dot(V,V) - sqr_radius);

	if (Det > 0) {

		d -= sqrtf(Det);

		if (d > 0 && d < dist)

		{

			dist = d;

			return true;

		}

	}

	return false;

}

bool Sphere::intersect_all(const Ray &ray, Float dist, vector<Float> &allts) const

{

	//allts = new vector<Float>();

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

	Float Vd = - dot(V, ray.dir);

	Float Det = Vd * Vd - (dot(V,V) - sqr_radius);

	if (Det > 0) {

		Det = sqrtf(Det);

		Float t1 = Vd - Det;

		Float t2 = Vd + 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() const

{

	BBox bbox = BBox();

	bbox.L = center - radius;

	bbox.H = center + radius;

	return bbox;

}

bool Box::intersect(const Ray &ray, Float &dist) const

{

	Float a,b;

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

	if (res && a < dist)

	{

		dist = a;

		return true;

	}

	else

		return false;

}

const Vector3 Box::normal(const Vector3 &P) const

{

	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;

}

#ifdef TRI_PLUCKER

inline void Plucker(const Vector3 &p, const Vector3 &q, Float* pl)

{

    pl[0] = p.x*q.y - q.x*p.y;

    pl[1] = p.x*q.z - q.x*p.z;

    pl[2] = p.x - q.x;

    pl[3] = p.y*q.z - q.y*p.z;

    pl[4] = p.z - q.z;

    pl[5] = q.y - p.y;

}

inline Float Side(const Float* pla, const Float* plb)

{

    return pla[0]*plb[4] + pla[1]*plb[5] + pla[2]*plb[3] + pla[4]*plb[0] + pla[5]*plb[1] + pla[3]*plb[2];

}

#endif

Triangle::Triangle(Vertex *aA, Vertex *aB, Vertex *aC, Material *amaterial)

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

{

	material = amaterial;

	const Vector3 c = B->P - A->P;

	const Vector3 b = C->P - A->P;

	N = cross(c, b);

	N.normalize();

#ifdef TRI_PLUCKER

	Plucker(B->P,C->P,pla);

	Plucker(C->P,A->P,plb);

	Plucker(A->P,B->P,plc);

#endif

#if defined(TRI_BARI) || defined(TRI_BARI_PRE)

	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;

	}

#endif

#ifdef TRI_BARI_PRE

	int u = (k + 1) % 3;

	int v = (k + 2) % 3;

	Float krec = 1.0 / N[k];

	nu = N[u] * krec;

	nv = N[v] * krec;

	nd = dot(N, A->P) * krec;

	// first line equation

	Float reci = 1.0f / (b[u] * c[v] - b[v] * c[u]);

	bnu = b[u] * reci;

	bnv = -b[v] * reci;

	// second line equation

	cnu = -c[u] * reci;

	cnv = c[v] * reci;

#endif

}

bool Triangle::intersect(const Ray &ray, Float &dist) const

{

#ifdef TRI_PLUCKER

	Float plr[6];

	Plucker(ray.o, ray.o+ray.dir, plr);

	const bool side0 = Side(plr, pla) >= 0.0;

	const bool side1 = Side(plr, plb) >= 0.0;

	if (side0 != side1)

		return false;

	const bool side2 = Side(plr, plc) >= 0.0;

	if (side0 != side2)

		return false;

	const Float t = - dot( (ray.o - A->P), N) / dot(ray.dir,N);

	if(t <= Eps || t >= dist)

		return false;

	dist = t;

	return true;

#endif

#if defined(TRI_BARI) || defined(TRI_BARI_PRE)

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

	const Vector3 &O = ray.o;

	const Vector3 &D = ray.dir;

	register const int u = modulo3[k+1];

	register const int v = modulo3[k+2];

#endif

#ifdef TRI_BARI_PRE

	const Float t = (nd - O[k] - nu * O[u] - nv * O[v]) / (D[k] + nu * D[u] + nv * D[v]);

	if (t >= dist || t < Eps)

		return false;

	const Float hu = O[u] + t * D[u] - A->P[u];

	const Float hv = O[v] + t * D[v] - A->P[v];

	const Float beta = hv * bnu + hu * bnv;

	if (beta < 0.)

		return false;

	const Float gamma = hu * cnv + hv * cnu;

	if (gamma < 0. || beta + gamma > 1.)

		return false;

	dist = t;

	return true;

#endif

#ifdef TRI_BARI

	// original barycentric coordinates based intesection

	// not optimized, just for reference

	const Vector3 c = B - A;

	const Vector3 b = C - A;

	// distance test

	const Float t = - dot( (O-A), N) / dot(D,N);

	if (t < Eps || t > dist)

		return false;

	// calc hitpoint

	const Float Hu = O[u] + t * D[u] - A[u];

	const Float Hv = O[v] + t * D[v] - A[v];

	const Float beta = (b[u] * Hv - b[v] * Hu) / (b[u] * c[v] - b[v] * c[u]);

	if (beta < 0)

		return false;

	const Float gamma = (c[v] * Hu - c[u] * Hv) / (b[u] * c[v] - b[v] * c[u]);

	if (gamma < 0)

		return false;

	if (beta+gamma > 1)

		return false;

	dist = t;

	return true;

#endif

}

BBox Triangle::get_bbox() const

{

	BBox bbox = BBox();

	bbox.L = A->P;

	if (B->P.x < bbox.L.x)  bbox.L.x = B->P.x;

	if (C->P.x < bbox.L.x)  bbox.L.x = C->P.x;

	if (B->P.y < bbox.L.y)  bbox.L.y = B->P.y;

	if (C->P.y < bbox.L.y)  bbox.L.y = C->P.y;

	if (B->P.z < bbox.L.z)  bbox.L.z = B->P.z;

	if (C->P.z < bbox.L.z)  bbox.L.z = C->P.z;

	bbox.H = A->P;

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

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

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

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

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

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

	return bbox;

};