ConvexHullBuilder2D.h

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// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <Jolt/Core/NonCopyable.h>
 
//#define JPH_CONVEX_BUILDER_2D_DEBUG
 
JPH_NAMESPACE_BEGIN
 
class ConvexHullBuilder2D : public NonCopyable
{
public:
    using Positions = Array<Vec3>; 
    using Edges = Array<int>;
 
    explicit            ConvexHullBuilder2D(const Positions &inPositions); 
 
                        ~ConvexHullBuilder2D();
 
    enum class EResult
    {
        Success,                                                    
        MaxVerticesReached,                                         
    };
 
    EResult             Initialize(int inIdx1, int inIdx2, int inIdx3, int inMaxVertices, float inTolerance, Edges &outEdges);
 
private:
#ifdef JPH_CONVEX_BUILDER_2D_DEBUG
    static constexpr Real cDrawScale = 10;
#endif
 
    class Edge;
 
    void                FreeEdges();
 
    void                AssignPointToEdge(int inPositionIdx, const Array<Edge *> &inEdges) const;
 
#ifdef JPH_CONVEX_BUILDER_2D_DEBUG
    void                DrawState();
#endif
 
#ifdef JPH_ENABLE_ASSERTS
    void                ValidateEdges() const;
#endif
 
    using ConflictList = Array<int>;
 
    class Edge
    {
    public:
        JPH_OVERRIDE_NEW_DELETE
 
        explicit        Edge(int inStartIdx)                        : mStartIdx(inStartIdx) { }
 
        void            CalculateNormalAndCenter(const Vec3 *inPositions);
 
        inline bool     IsFacing(Vec3Arg inPosition) const          { return mNormal.Dot(inPosition - mCenter) > 0.0f; }
 
        Vec3            mNormal;                                    
        Vec3            mCenter;                                    
        ConflictList    mConflictList;                              
        Edge *          mPrevEdge = nullptr;                        
        Edge *          mNextEdge = nullptr;                        
        int             mStartIdx;                                  
        float           mFurthestPointDistanceSq = 0.0f;            
    };
 
    const Positions &   mPositions;                                 
    Edge *              mFirstEdge = nullptr;                       
    int                 mNumEdges = 0;                              
 
#ifdef JPH_CONVEX_BUILDER_2D_DEBUG
    RVec3               mOffset;                                    
    Vec3                mDelta;                                     
#endif
};
 
JPH_NAMESPACE_END