softbody internal functions

[guernika]

Dear all,

I'm trying to understand what is the output of the functions ProjectOrigin and BaryCoord, contained in the file btSoftbodyInternals.h.
Any suggestion will be appreciated.
Thanks in advance,
Francesco

Code: Select all

static inline btVector3		BaryCoord(	const btVector3& a,
									  const btVector3& b,
									  const btVector3& c,
									  const btVector3& p)
{
	const btScalar	w[]={	btCross(a-p,b-p).length(),
		btCross(b-p,c-p).length(),
		btCross(c-p,a-p).length()};
	const btScalar	isum=1/(w[0]+w[1]+w[2]);
	return(btVector3(w[1]*isum,w[2]*isum,w[0]*isum));
}

static inline void			
	ProjectOrigin(	const btVector3& a,
				  const btVector3& b,
				  btVector3& prj,
				  btScalar& sqd)
{
	const btVector3	d=b-a;
	const btScalar	m2=d.length2();
	if(m2>SIMD_EPSILON)
	{	
		const btScalar	t=Clamp<btScalar>(-btDot(a,d)/m2,0,1);
		const btVector3	p=a+d*t;
		const btScalar	l2=p.length2();
		if(l2<sqd)
		{
			prj=p;
			sqd=l2;
		}
	}
}

static inline void			
	ProjectOrigin(	const btVector3& a,
					  const btVector3& b,
					  const btVector3& c,
					  btVector3& prj,
					  btScalar& sqd)
{
	const btVector3&	q=btCross(b-a,c-a);
	const btScalar		m2=q.length2();
	if(m2>SIMD_EPSILON)
	{
		const btVector3	n=q/btSqrt(m2);
		const btScalar	k=btDot(a,n);
		const btScalar	k2=k*k;
		if(k2<sqd)
		{
			const btVector3	p=n*k;
			if(	(btDot(btCross(a-p,b-p),q)>0)&&
				(btDot(btCross(b-p,c-p),q)>0)&&
				(btDot(btCross(c-p,a-p),q)>0))
			{			
				prj=p;
				sqd=k2;
			}
			else
			{
				ProjectOrigin(a,b,prj,sqd);
				ProjectOrigin(b,c,prj,sqd);
				ProjectOrigin(c,a,prj,sqd);
			}
		}
	}
}