//// Ray to sphere collision test//	http://www.cs.unc.edu/~rademach/xroads-RT/RTarticle.html//const bool Util::RaySphereTest( D3DXVECTOR3* vPofI, const D3DXVECTOR3* vSpherePos, const float fRadius, 								const D3DXVECTOR3* vRayStartPos, const D3DXVECTOR3* vRayEndPos ){	// Ray''s direction	D3DXVECTOR3 vRayNormal = *vRayEndPos - *vRayStartPos;	Normalize( &vRayNormal, &vRayNormal );	// Get distance of a vector from ray origin to sphere''s center pos projected on the ray	D3DXVECTOR3 vRaySphere = *vSpherePos - *vRayStartPos;	float dist = DotProd( &vRaySphere, &vRayNormal );	// Find distance from point of intersection to vector perpendicular to ray and goes through sphere''s 	//	center (that''s the idea anyway)	float disc = (fRadius * fRadius) - (DotProd( &vRaySphere, &vRaySphere ) - (dist * dist) );	if( disc < 0.0f ) 		return false;	// No intersection	// They intersect	if( vPofI )	{		// Find point of intersection		float d = (float)sqrt( disc );		*vPofI = *vRayStartPos + ((dist - d) * vRayNormal);	}	return true;}