/*
 * 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 "MultiSphereShape.h"
#include "CollisionShapes/CollisionMargin.h"
#include "SimdQuaternion.h"

MultiSphereShape::MultiSphereShape (const SimdVector3& inertiaHalfExtents,const SimdVector3* positions,const SimdScalar* radi,int numSpheres)
:m_inertiaHalfExtents(inertiaHalfExtents)
{
	m_minRadius = 1e30f;

	m_numSpheres = numSpheres;
	for (int i=0;i<m_numSpheres;i++)
	{
		m_localPositions[i] = positions[i];
		m_radi[i] = radi[i];
		if (radi[i] < m_minRadius)
			m_minRadius = radi[i];
	}
	SetMargin(m_minRadius);

}



 
 SimdVector3	MultiSphereShape::LocalGetSupportingVertexWithoutMargin(const SimdVector3& vec0)const
{
	int i;
	SimdVector3 supVec(0,0,0);

	SimdScalar maxDot(-1e30f);


	SimdVector3 vec = vec0;
	SimdScalar lenSqr = vec.length2();
	if (lenSqr < 0.0001f)
	{
		vec.setValue(1,0,0);
	} else
	{
		float rlen = 1.f / SimdSqrt(lenSqr );
		vec *= rlen;
	}

	SimdVector3 vtx;
	SimdScalar newDot;

	const SimdVector3* pos = &m_localPositions[0];
	const SimdScalar* rad = &m_radi[0];

	for (i=0;i<m_numSpheres;i++)
	{
		vtx = (*pos) +vec*((*rad)-m_minRadius);
		pos++;
		rad++;
		newDot = vec.dot(vtx);
		if (newDot > maxDot)
		{
			maxDot = newDot;
			supVec = vtx;
		}
	}

	return supVec;

}










void	MultiSphereShape::CalculateLocalInertia(SimdScalar mass,SimdVector3& inertia)
{
	//as an approximation, take the inertia of the box that bounds the spheres

	SimdTransform ident;
	ident.setIdentity();
//	SimdVector3 aabbMin,aabbMax;

//	GetAabb(ident,aabbMin,aabbMax);

	SimdVector3 halfExtents = m_inertiaHalfExtents;//(aabbMax - aabbMin)* 0.5f;

	float margin = CONVEX_DISTANCE_MARGIN;

	SimdScalar lx=2.f*(halfExtents[0]+margin);
	SimdScalar ly=2.f*(halfExtents[1]+margin);
	SimdScalar lz=2.f*(halfExtents[2]+margin);
	const SimdScalar x2 = lx*lx;
	const SimdScalar y2 = ly*ly;
	const SimdScalar z2 = lz*lz;
	const SimdScalar scaledmass = mass * 0.08333333f;

	inertia[0] = scaledmass * (y2+z2);
	inertia[1] = scaledmass * (x2+z2);
	inertia[2] = scaledmass * (x2+y2);

}