SDFCalculationUtils.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Math/MathFwd.h"
#include "Math/Vector.h"
#include "VectorTypes.h"
 
namespace UE
{
namespace Geometry
{
    using namespace UE::Math;
 
    // These are utility functions shared by the various SDF calculation implementations
    // (CachingMeshSDF, SweepignMeshSDF, SparseNarrowBandMeshSDF)
 
 
    GEOMETRYCORE_API double PointTriangleDistance(const FVector3d& x0, const FVector3d& x1, const FVector3d& x2, const FVector3d& x3);
 
    GEOMETRYCORE_API float PointTriangleDistance(const FVector3f& x0, const FVector3f& x1, const FVector3f& x2, const FVector3f& x3);
 
 
    GEOMETRYCORE_API bool PointInTriangle2d(double X0, double Y0, double X1, double Y1, double X2, double Y2, double X3, double Y3, double& A, double& B, double& C);
 
    // find distance x0 is from segment x1-x2
    template<typename RealType> 
    RealType PointSegmentDistance(const TVector<RealType>& x0, const TVector<RealType>& x1, const TVector<RealType>& x2)
    {
        TVector<RealType> DX = x2 - x1;
        RealType m2 = DX.SquaredLength();
        // find parameter value of closest point on segment
        RealType s12 = (DX.Dot(x2 - x0) / m2);
        if (s12 < 0)
        {
            s12 = 0;
        }
        else if (s12 > 1)
        {
            s12 = 1;
        }
        // and find the distance
        return Distance(x0, s12*x1 + (1.0 - s12)*x2);
    }
 
 
    // calculate twice signed area of triangle (0,0)-(X1,Y1)-(X2,Y2)
    // return an SOS-determined sign (-1, +1, or 0 only if it's a truly degenerate triangle)
    template<typename RealType> 
    int Orientation(RealType X1, RealType Y1, RealType X2, RealType Y2, RealType& TwiceSignedArea)
    {
        TwiceSignedArea = Y1 * X2 - X1 * Y2;
        if (TwiceSignedArea > 0) return 1;
        else if (TwiceSignedArea < 0) return -1;
        else if (Y2 > Y1) return 1;
        else if (Y2 < Y1) return -1;
        else if (X1 > X2) return 1;
        else if (X1 < X2) return -1;
        else return 0; // only true when X1==X2 and Y1==Y2
    }
 
 
 
 
}
}