/*
 * Copyright (c) 2005 Erwin Coumans http://continuousphysics.com/Bullet/
 *
 * Permission to use, copy, modify, distribute and sell this software
 * and its documentation for any purpose is hereby granted without fee,
 * provided that the above copyright notice appear in all copies.
 * Erwin Coumans makes no representations about the suitability 
 * of this software for any purpose.  
 * It is provided "as is" without express or implied warranty.
*/

#include "SubSimplexConvexCast.h"
#include "CollisionShapes/ConvexShape.h"
#include "CollisionShapes/MinkowskiSumShape.h"
#include "NarrowPhaseCollision/SimplexSolverInterface.h"


SubsimplexConvexCast::SubsimplexConvexCast (ConvexShape* convexA,ConvexShape* convexB,SimplexSolverInterface* simplexSolver)
:m_simplexSolver(simplexSolver),
m_convexA(convexA),m_convexB(convexB)
{
}


#define MAX_ITERATIONS 1000

bool	SubsimplexConvexCast::calcTimeOfImpact(
		const SimdTransform& fromA,
		const SimdTransform& toA,
		const SimdTransform& fromB,
		const SimdTransform& toB,
		CastResult& result)
{

		MinkowskiSumShape combi(m_convexA,m_convexB);
	MinkowskiSumShape* convex = &combi;

	SimdTransform	rayFromLocalA;
	SimdTransform	rayToLocalA;

	rayFromLocalA = fromA.inverse()* fromB;
	rayToLocalA = toA.inverse()* toB;


	m_simplexSolver->reset();

	convex->SetTransformB(SimdTransform(rayFromLocalA.getBasis()));

	float radius = 0.01f;

	SimdScalar lambda = 0.f;
	SimdVector3 s = rayFromLocalA.getOrigin();
	SimdVector3 r = rayToLocalA.getOrigin()-rayFromLocalA.getOrigin();
	SimdVector3 x = s;
	SimdVector3 v;
	SimdVector3 arbitraryPoint = convex->LocalGetSupportingVertex(r);
	
	v = x - arbitraryPoint;

	int maxIter = MAX_ITERATIONS;

	SimdVector3 n;
	n.setValue(0.f,0.f,0.f);
	bool hasResult = false;
	SimdVector3 c;

	float lastLambda = lambda;


	float dist2 = v.length2();
	float epsilon = 0.0001f;

	SimdVector3	w,p;
	float VdotR;
	
	while ( (dist2 > epsilon) && maxIter--)
	{
		p = convex->LocalGetSupportingVertex( v);
		 w = x - p;

		float VdotW = v.dot(w);

		if ( VdotW > 0.f)
		{
			VdotR = v.dot(r);

			if (VdotR >= 0.f)
				return false;
			else
			{
				lambda = lambda - VdotW / VdotR;
				x = s + lambda * r;
				m_simplexSolver->reset();
				//check next line
				w = x-p;
				lastLambda = lambda;
				n = v;
				hasResult = true;
			}
		} 
		m_simplexSolver->addVertex( w, x , p);
		if (m_simplexSolver->closest(v))
		{
			dist2 = v.length2();
			hasResult = true;
			//printf("V=%f , %f, %f\n",v[0],v[1],v[2]);
			//printf("DIST2=%f\n",dist2);
			//printf("numverts = %i\n",m_simplexSolver->numVertices());
		} else
		{
			dist2 = 0.f;
		} 
	}

	int numiter = MAX_ITERATIONS - maxIter;
//	printf("number of iterations: %d", numiter);
	result.m_fraction = lambda;
	result.m_normal = n;

	return true;
}