GuDistancePointTriangle.h

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#ifndef GU_DISTANCE_POINT_TRIANGLE_H
#define GU_DISTANCE_POINT_TRIANGLE_H
 
#include "foundation/PxVec3.h"
#include "common/PxPhysXCommonConfig.h"
 
namespace physx
{
namespace Gu
{
    // PT: special version:
    // - inlined
    // - doesn't compute (s,t) output params
    // - expects precomputed edges in input
    PX_FORCE_INLINE PX_CUDA_CALLABLE 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