text: // MIT License
  
  // Copyright (c) 2019 Erin Catto
  
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  
  // The above copyright notice and this permission notice shall be included in all
  // copies or substantial portions of the Software.
  
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  // SOFTWARE.
  
  #ifndef B2_CHAIN_SHAPE_H
  #define B2_CHAIN_SHAPE_H
  
  #include "b2_shape.h"
  
  class b2EdgeShape;
  
  /// A chain shape is a free form sequence of line segments.
  /// The chain has one-sided collision, with the surface normal pointing to the right of the edge.
  /// This provides a counter-clockwise winding like the polygon shape.
  /// Connectivity information is used to create smooth collisions.
  /// @warning the chain will not collide properly if there are self-intersections.
  class b2ChainShape : public b2Shape
  {
  public:
  	b2ChainShape();
  
  	/// The destructor frees the vertices using b2Free.
  	~b2ChainShape();
  
  	/// Clear all data.
  	void Clear();
  
  	/// Create a loop. This automatically adjusts connectivity.
  	/// @param vertices an array of vertices, these are copied
  	/// @param count the vertex count
  	void CreateLoop(const b2Vec2* vertices, int32 count);
  
  	/// Create a chain with ghost vertices to connect multiple chains together.
  	/// @param vertices an array of vertices, these are copied
  	/// @param count the vertex count
  	/// @param prevVertex previous vertex from chain that connects to the start
  	/// @param nextVertex next vertex from chain that connects to the end
  	void CreateChain(const b2Vec2* vertices, int32 count,
  		const b2Vec2& prevVertex, const b2Vec2& nextVertex);
  
  	/// Implement b2Shape. Vertices are cloned using b2Alloc.
  	b2Shape* Clone(b2BlockAllocator* allocator) const override;
  
  	/// @see b2Shape::GetChildCount
  	int32 GetChildCount() const override;
  
  	/// Get a child edge.
  	void GetChildEdge(b2EdgeShape* edge, int32 index) const;
  
  	/// This always return false.
  	/// @see b2Shape::TestPoint
  	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const override;
  
  	// @see b2Shape::ComputeDistance
  	void ComputeDistance(const b2Transform& xf, const b2Vec2& p, float* distance, b2Vec2* normal, int32 childIndex) const override;
  
  	/// Implement b2Shape.
  	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
  					const b2Transform& transform, int32 childIndex) const override;
  
  	/// @see b2Shape::ComputeAABB
  	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const override;
  
  	/// Chains have zero mass.
  	/// @see b2Shape::ComputeMass
  	void ComputeMass(b2MassData* massData, float density) const override;
  
  	/// The vertices. Owned by this class.
  	b2Vec2* m_vertices;
  
  	/// The vertex count.
  	int32 m_count;
  
  	b2Vec2 m_prevVertex, m_nextVertex;
  };
  
  inline b2ChainShape::b2ChainShape()
  {
  	m_type = e_chain;
  	m_radius = b2_polygonRadius;
  	m_vertices = nullptr;
  	m_count = 0;
  }
  
  #endif
  