initial commit, 4.5 stable

thirdparty/jolt_physics/Jolt/Geometry/ConvexHullBuilder2D.h

@@ -0,0 +1,105 @@
+// 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
+
+/// A convex hull builder that tries to create 2D hulls as accurately as possible. Used for offline processing.
+class JPH_EXPORT ConvexHullBuilder2D : public NonCopyable
+{
+public:
+	using Positions = Array<Vec3>;
+	using Edges = Array<int>;
+
+	/// Constructor
+	/// @param inPositions Positions used to make the hull. Uses X and Y component of Vec3 only!
+	explicit			ConvexHullBuilder2D(const Positions &inPositions);
+
+	/// Destructor
+						~ConvexHullBuilder2D();
+
+	/// Result enum that indicates how the hull got created
+	enum class EResult
+	{
+		Success,													///< Hull building finished successfully
+		MaxVerticesReached,											///< Hull building finished successfully, but the desired accuracy was not reached because the max vertices limit was reached
+	};
+
+	/// Takes all positions as provided by the constructor and use them to build a hull
+	/// Any points that are closer to the hull than inTolerance will be discarded
+	/// @param inIdx1 , inIdx2 , inIdx3 The indices to use as initial hull (in any order)
+	/// @param inMaxVertices Max vertices to allow in the hull. Specify INT_MAX if there is no limit.
+	/// @param inTolerance Max distance that a point is allowed to be outside of the hull
+	/// @param outEdges On success this will contain the list of indices that form the hull (counter clockwise)
+	/// @return Status code that reports if the hull was created or not
+	EResult				Initialize(int inIdx1, int inIdx2, int inIdx3, int inMaxVertices, float inTolerance, Edges &outEdges);
+
+private:
+#ifdef JPH_CONVEX_BUILDER_2D_DEBUG
+	/// Factor to scale convex hull when debug drawing the construction process
+	static constexpr Real cDrawScale = 10;
+#endif
+
+	class Edge;
+
+	/// Frees all edges
+	void				FreeEdges();
+
+	/// Assigns a position to one of the supplied edges based on which edge is closest.
+	/// @param inPositionIdx Index of the position to add
+	/// @param inEdges List of edges to consider
+	void				AssignPointToEdge(int inPositionIdx, const Array<Edge *> &inEdges) const;
+
+#ifdef JPH_CONVEX_BUILDER_2D_DEBUG
+	/// Draw state of algorithm
+	void				DrawState();
+#endif
+
+#ifdef JPH_ENABLE_ASSERTS
+	/// Validate that the edge structure is intact
+	void				ValidateEdges() const;
+#endif
+
+	using ConflictList = Array<int>;
+
+	/// Linked list of edges
+	class Edge
+	{
+	public:
+		JPH_OVERRIDE_NEW_DELETE
+
+		/// Constructor
+		explicit		Edge(int inStartIdx)						: mStartIdx(inStartIdx) { }
+
+		/// Calculate the center of the edge and the edge normal
+		void			CalculateNormalAndCenter(const Vec3 *inPositions);
+
+		/// Check if this edge is facing inPosition
+		inline bool		IsFacing(Vec3Arg inPosition) const			{ return mNormal.Dot(inPosition - mCenter) > 0.0f; }
+
+		Vec3			mNormal;									///< Normal of the edge (not normalized)
+		Vec3			mCenter;									///< Center of the edge
+		ConflictList	mConflictList;								///< Positions associated with this edge (that are closest to this edge). Last entry is the one furthest away from the edge, remainder is unsorted.
+		Edge *			mPrevEdge = nullptr;						///< Previous edge in circular list
+		Edge *			mNextEdge = nullptr;						///< Next edge in circular list
+		int				mStartIdx;									///< Position index of start of this edge
+		float			mFurthestPointDistanceSq = 0.0f;			///< Squared distance of furthest point from the conflict list to the edge
+	};
+
+	const Positions &	mPositions;									///< List of positions (some of them are part of the hull)
+	Edge *				mFirstEdge = nullptr;						///< First edge of the hull
+	int					mNumEdges = 0;								///< Number of edges in hull
+
+#ifdef JPH_CONVEX_BUILDER_2D_DEBUG
+	RVec3				mOffset;									///< Offset to use for state drawing
+	Vec3				mDelta;										///< Delta offset between next states
+#endif
+};
+
+JPH_NAMESPACE_END