DistSegment3Triangle3.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
// Port of geometry3Sharp DistSegment3Triangle3
// which was ported from WildMagic 5 
 
#pragma once
 
#include "VectorTypes.h"
#include "TriangleTypes.h"
#include "SegmentTypes.h"
#include "DistLine3Triangle3.h"
#include "DistPoint3Triangle3.h"
 
namespace UE
{
namespace Geometry
{
 
using namespace UE::Math;
 
template <typename Real>
class TDistSegment3Triangle3
{
public:
    // Input
    TSegment3<Real> Segment;
    TTriangle3<Real> Triangle;
 
    // Output
    Real DistanceSquared = -1.0;
    Real SegmentParameter;
    TVector<Real> TriangleClosest, TriangleBaryCoords, SegmentClosest;
    
    TDistSegment3Triangle3(const TSegment3<Real>& SegmentIn, const TTriangle3<Real>& TriangleIn) : Segment(SegmentIn), Triangle(TriangleIn)
    {
    }
 
    Real Get() 
    {
        return TMathUtil<Real>::Sqrt(ComputeResult());
    }
    Real GetSquared()
    {
        return ComputeResult();
    }
 
    Real ComputeResult()
    {
        if (DistanceSquared >= 0)
        {
            return DistanceSquared;
        }
 
        TLine3<Real> line(Segment.Center, Segment.Direction);
        TDistLine3Triangle3<Real> queryLT(line, Triangle);
        double sqrDist = queryLT.GetSquared();
        SegmentParameter = queryLT.LineParam;
 
        if (SegmentParameter >= -Segment.Extent) {
            if (SegmentParameter <= Segment.Extent) {
                SegmentClosest = queryLT.LineClosest;
                TriangleClosest = queryLT.TriangleClosest;
                TriangleBaryCoords = queryLT.TriangleBaryCoords;
            }
            else {
                SegmentClosest = Segment.EndPoint();
                TDistPoint3Triangle3<Real> queryPT(SegmentClosest, Triangle);
                sqrDist = queryPT.GetSquared();
                TriangleClosest = queryPT.ClosestTrianglePoint;
                SegmentParameter = Segment.Extent;
                TriangleBaryCoords = queryPT.TriangleBaryCoords;
            }
        }
        else {
            SegmentClosest = Segment.StartPoint();
            TDistPoint3Triangle3<Real> queryPT(SegmentClosest, Triangle);
            sqrDist = queryPT.GetSquared();
            TriangleClosest = queryPT.ClosestTrianglePoint;
            SegmentParameter = -Segment.Extent;
            TriangleBaryCoords = queryPT.TriangleBaryCoords;
        }
 
        DistanceSquared = sqrDist;
        return DistanceSquared;
    }
};
 
typedef TDistSegment3Triangle3<float> FDistSegment3Triangle3f;
typedef TDistSegment3Triangle3<double> FDistSegment3Triangle3d;
 
} // end namespace UE::Geometry
} // end namespace UE