DistTriangle3Triangle3.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
 
// Port of geometry3Sharp DistTriangle3Triangle3
// which was ported from WildMagic 5 
 
 
#pragma once
 
#include "VectorTypes.h"
#include "TriangleTypes.h"
#include "SegmentTypes.h"
#include "DistSegment3Triangle3.h"
#include "DistPoint3Triangle3.h"
 
namespace UE
{
namespace Geometry
{
 
using namespace UE::Math;
 
template <typename Real>
class TDistTriangle3Triangle3
{
public:
    // Output
    Real DistanceSquared = -1.0;
    TVector<Real> TriangleClosest[2];
    TVector<Real> TriangleBaryCoords[2];
 
 
    TDistTriangle3Triangle3()
    {
    }
    TDistTriangle3Triangle3(const TTriangle3<Real>& TriangleA, const TTriangle3<Real>& TriangleB)
    {
        Triangle[0] = TriangleA;
        Triangle[1] = TriangleB;
    }
 
    void SetTriangle(int WhichTriangle, const TTriangle3<Real>& TriangleIn)
    {
        check(WhichTriangle >= 0 && WhichTriangle < 2);
        Triangle[WhichTriangle] = TriangleIn;
        DistanceSquared = -1.0; // clear cached result
    }
 
    Real Get()
    {
        return TMathUtil<Real>::Sqrt(ComputeResult());
    }
    Real GetSquared()
    {
        return ComputeResult();
    }
 
    Real ComputeResult()
    {
        if (DistanceSquared >= 0)
        {
            return DistanceSquared;
        }
 
 
        // Compare edges of Triangle[0] to the interior of Triangle[1].
        Real sqrDist = TMathUtil<Real>::MaxReal, sqrDistTmp;
        Real ratio;
        int i0, i1;
        for (i0 = 2, i1 = 0; i1 < 3; i0 = i1++)
        {
            TSegment3<Real> edge(Triangle[0].V[i0], Triangle[0].V[i1]);
 
            TDistSegment3Triangle3<Real> queryST(edge, Triangle[1]);
            sqrDistTmp = queryST.GetSquared();
            if (sqrDistTmp < sqrDist)
            {
                TriangleClosest[0] = queryST.SegmentClosest;
                TriangleClosest[1] = queryST.TriangleClosest;
                sqrDist = sqrDistTmp;
 
                ratio = queryST.SegmentParameter / edge.Extent;
                TriangleBaryCoords[0][i0] = (0.5) * (1 - ratio);
                TriangleBaryCoords[0][i1] = 1 - TriangleBaryCoords[0][i0];
                TriangleBaryCoords[0][3 - i0 - i1] = 0;
                TriangleBaryCoords[1] = queryST.TriangleBaryCoords;
 
                if (sqrDist <= TMathUtil<Real>::ZeroTolerance)
                {
                    DistanceSquared = 0;
                    return 0;
                }
            }
        }
 
        // Compare edges of Triangle[1] to the interior of Triangle[0].
        for (i0 = 2, i1 = 0; i1 < 3; i0 = i1++)
        {
            TSegment3<Real> edge(Triangle[1].V[i0], Triangle[1].V[i1]);
 
            TDistSegment3Triangle3<Real> queryST(edge, Triangle[0]);
            sqrDistTmp = queryST.GetSquared();
            if (sqrDistTmp < sqrDist)
            {
                TriangleClosest[0] = queryST.SegmentClosest;
                TriangleClosest[1] = queryST.TriangleClosest;
                sqrDist = sqrDistTmp;
 
                ratio = queryST.SegmentParameter / edge.Extent;
                TriangleBaryCoords[1][i0] = (0.5) * (1 - ratio);
                TriangleBaryCoords[1][i1] = 1 - TriangleBaryCoords[1][i0];
                TriangleBaryCoords[1][3 - i0 - i1] = 0;
                TriangleBaryCoords[0] = queryST.TriangleBaryCoords;
 
                if (sqrDist <= TMathUtil<Real>::ZeroTolerance)
                {
                    DistanceSquared = 0;
                    return 0;
                }
            }
        }
 
 
        DistanceSquared = sqrDist;
        return DistanceSquared;
    }
    
private:
 
    // Input triangles; must be set via SetTriangle to clear cached result
    TTriangle3<Real> Triangle[2];
};
 
typedef TDistTriangle3Triangle3<float> FDistTriangle3Triangle3f;
typedef TDistTriangle3Triangle3<double> FDistTriangle3Triangle3d;
 
} // end namespace UE::Geometry
} // end namespace UE