text: //
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  // Copyright (c) 2008-2019 NVIDIA Corporation. All rights reserved.
  // Copyright (c) 2004-2008 AGEIA Technologies, Inc. All rights reserved.
  // Copyright (c) 2001-2004 NovodeX AG. All rights reserved.  
  
  #ifndef GU_DISTANCE_POINT_TRIANGLE_H
  #define GU_DISTANCE_POINT_TRIANGLE_H
  
  #include "foundation/PxVec3.h"
  #include "common/PxPhysXCommonConfig.h"
  #include "CmPhysXCommon.h"
  
  namespace physx
  {
  namespace Gu
  {
  	// PT: special version:
  	// - inlined
  	// - doesn't compute (s,t) output params
  	// - expects precomputed edges in input
  	PX_FORCE_INLINE PxVec3 closestPtPointTriangle2(const PxVec3& p, const PxVec3& a, const PxVec3& b, const PxVec3& c, const PxVec3& ab, const PxVec3& ac)
  	{
  		// Check if P in vertex region outside A
  		//const PxVec3 ab = b - a;
  		//const PxVec3 ac = c - a;
  		const PxVec3 ap = p - a;
  		const float d1 = ab.dot(ap);
  		const float d2 = ac.dot(ap);
  		if(d1<=0.0f && d2<=0.0f)
  			return a;	// Barycentric coords 1,0,0
  
  		// Check if P in vertex region outside B
  		const PxVec3 bp = p - b;
  		const float d3 = ab.dot(bp);
  		const float d4 = ac.dot(bp);
  		if(d3>=0.0f && d4<=d3)
  			return b;	// Barycentric coords 0,1,0
  
  		// Check if P in edge region of AB, if so return projection of P onto AB
  		const float vc = d1*d4 - d3*d2;
  		if(vc<=0.0f && d1>=0.0f && d3<=0.0f)
  		{
  			const float v = d1 / (d1 - d3);
  			return a + v * ab;	// barycentric coords (1-v, v, 0)
  		}
  
  		// Check if P in vertex region outside C
  		const PxVec3 cp = p - c;
  		const float d5 = ab.dot(cp);
  		const float d6 = ac.dot(cp);
  		if(d6>=0.0f && d5<=d6)
  			return c;	// Barycentric coords 0,0,1
  
  		// Check if P in edge region of AC, if so return projection of P onto AC
  		const float vb = d5*d2 - d1*d6;
  		if(vb<=0.0f && d2>=0.0f && d6<=0.0f)
  		{
  			const float w = d2 / (d2 - d6);
  			return a + w * ac;	// barycentric coords (1-w, 0, w)
  		}
  
  		// Check if P in edge region of BC, if so return projection of P onto BC
  		const float va = d3*d6 - d5*d4;
  		if(va<=0.0f && (d4-d3)>=0.0f && (d5-d6)>=0.0f)
  		{
  			const float w = (d4-d3) / ((d4 - d3) + (d5-d6));
  			return b + w * (c-b);	// barycentric coords (0, 1-w, w)
  		}
  
  		// P inside face region. Compute Q through its barycentric coords (u,v,w)
  		const float denom = 1.0f / (va + vb + vc);
  		const float v = vb * denom;
  		const float w = vc * denom;
  		return a + ab*v + ac*w;
  	}
  
  	PX_PHYSX_COMMON_API PxVec3 closestPtPointTriangle(const PxVec3& p, const PxVec3& a, const PxVec3& b, const PxVec3& c, float& s, float& t);
  
  	PX_FORCE_INLINE PxReal distancePointTriangleSquared(const PxVec3& point, 
  														const PxVec3& triangleOrigin, 
  														const PxVec3& triangleEdge0, 
  														const PxVec3& triangleEdge1,
  														PxReal* param0=NULL, 
  														PxReal* param1=NULL)
  	{
  		const PxVec3 pt0 = triangleEdge0 + triangleOrigin;
  		const PxVec3 pt1 = triangleEdge1 + triangleOrigin;
  		float s,t;
  		const PxVec3 cp = closestPtPointTriangle(point, triangleOrigin, pt0, pt1, s, t);
  		if(param0)
  			*param0 = s;
  		if(param1)
  			*param1 = t;
  		return (cp - point).magnitudeSquared();
  	}
  
  } // namespace Gu
  
  }
  
  #endif
  