DistSegment2AxisAlignedBox2.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
// Port of gte's DistSegment2AlignedBox2 to use GeometryCore data types
 
#pragma once
 
#include "DistLine2AxisAlignedBox2.h"
#include "Math/Box2D.h"
#include "SegmentTypes.h"
#include "VectorTypes.h"
 
namespace UE
{
namespace Geometry
{
 
using namespace UE::Math;
 
template <typename Real>
class TDistSegment2AxisAlignedBox2
{
public:
    // Input
    TSegment2<Real> Segment;
    TBox2<Real> AxisAlignedBox;
 
    // Output
    Real DistanceSquared = -1.0;
    Real SegmentParameter;
    TVector2<Real> BoxClosest, SegmentClosest;
 
    TDistSegment2AxisAlignedBox2(const TSegment2<Real>& SegmentIn, const TBox2<Real>& AxisAlignedBoxIn) : Segment(SegmentIn), AxisAlignedBox(AxisAlignedBoxIn)
    {
    }
 
    Real Get() 
    {
        return TMathUtil<Real>::Sqrt(ComputeResult());
    }
    Real GetSquared()
    {
        return ComputeResult();
    }
 
    Real ComputeResult()
    {
        if (DistanceSquared >= 0)
        {
            return DistanceSquared;
        }
 
        TLine2<Real> line(Segment.Center, Segment.Direction);
        TDistLine2AxisAlignedBox2<Real> queryLB(line, AxisAlignedBox);
        Real sqrDist = queryLB.GetSquared();
        SegmentParameter = queryLB.LineParameter;
 
        if (SegmentParameter >= -Segment.Extent) {
            if (SegmentParameter <= Segment.Extent) {
                SegmentClosest = queryLB.LineClosest;
                BoxClosest = queryLB.BoxClosest;
            }
            else {
                SegmentClosest = Segment.EndPoint();
                BoxClosest = AxisAlignedBox.GetClosestPointTo(SegmentClosest);
                sqrDist = (SegmentClosest - BoxClosest).SquaredLength();
                SegmentParameter = Segment.Extent;
            }
        }
        else {
            SegmentClosest = Segment.StartPoint();
            BoxClosest = AxisAlignedBox.GetClosestPointTo(SegmentClosest);
            sqrDist = (SegmentClosest - BoxClosest).SquaredLength();
            SegmentParameter = -Segment.Extent;
        }
 
        DistanceSquared = sqrDist;
        return DistanceSquared;
    }
};
 
typedef TDistSegment2AxisAlignedBox2<float> FDistSegment2AxisAlignedBox2f;
typedef TDistSegment2AxisAlignedBox2<double> FDistSegment2AxisAlignedBox2d;
 
} // end namespace UE::Geometry
} // end namespace UE