1/*
2* Copyright (c) 2006-2010 Erin Catto http://www.box2d.org
3*
4* This software is provided 'as-is', without any express or implied
5* warranty.  In no event will the authors be held liable for any damages
6* arising from the use of this software.
7* Permission is granted to anyone to use this software for any purpose,
8* including commercial applications, and to alter it and redistribute it
9* freely, subject to the following restrictions:
10* 1. The origin of this software must not be misrepresented; you must not
11* claim that you wrote the original software. If you use this software
12* in a product, an acknowledgment in the product documentation would be
13* appreciated but is not required.
14* 2. Altered source versions must be plainly marked as such, and must not be
15* misrepresented as being the original software.
16* 3. This notice may not be removed or altered from any source distribution.
17*/
18
19#ifndef B2_CHAIN_SHAPE_H
20#define B2_CHAIN_SHAPE_H
21
22#include <Box2D/Collision/Shapes/b2Shape.h>
23
24class b2EdgeShape;
25
26/// A chain shape is a free form sequence of line segments.
27/// The chain has two-sided collision, so you can use inside and outside collision.
28/// Therefore, you may use any winding order.
29/// Since there may be many vertices, they are allocated using b2Alloc.
30/// Connectivity information is used to create smooth collisions.
31/// WARNING: The chain will not collide properly if there are self-intersections.
32class b2ChainShape : public b2Shape
33{
34public:
35	b2ChainShape();
36
37	/// The destructor frees the vertices using b2Free.
38	~b2ChainShape();
39
40	/// Clear all data.
41	void Clear();
42
43	/// Create a loop. This automatically adjusts connectivity.
44	/// @param vertices an array of vertices, these are copied
45	/// @param count the vertex count
46	void CreateLoop(const b2Vec2* vertices, int32 count);
47
48	/// Create a chain with isolated end vertices.
49	/// @param vertices an array of vertices, these are copied
50	/// @param count the vertex count
51	void CreateChain(const b2Vec2* vertices, int32 count);
52
53	/// Establish connectivity to a vertex that precedes the first vertex.
54	/// Don't call this for loops.
55	void SetPrevVertex(const b2Vec2& prevVertex);
56
57	/// Establish connectivity to a vertex that follows the last vertex.
58	/// Don't call this for loops.
59	void SetNextVertex(const b2Vec2& nextVertex);
60
61	/// Implement b2Shape. Vertices are cloned using b2Alloc.
62	b2Shape* Clone(b2BlockAllocator* allocator) const;
63
64	/// @see b2Shape::GetChildCount
65	int32 GetChildCount() const;
66
67	/// Get a child edge.
68	void GetChildEdge(b2EdgeShape* edge, int32 index) const;
69
70	/// This always return false.
71	/// @see b2Shape::TestPoint
72	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
73
74	/// Implement b2Shape.
75	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
76					const b2Transform& transform, int32 childIndex) const;
77
78	/// @see b2Shape::ComputeAABB
79	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const;
80
81	/// Chains have zero mass.
82	/// @see b2Shape::ComputeMass
83	void ComputeMass(b2MassData* massData, float32 density) const;
84
85	/// Get the number of vertices.
86	int32 GetVertexCount() const { return m_count; }
87
88	/// Get the vertices (read-only).
89	const b2Vec2& GetVertex(int32 index) const
90	{
91		b2Assert(0 <= index && index < m_count);
92		return m_vertices[index];
93	}
94
95	/// Get the vertices (read-only).
96	const b2Vec2* GetVertices() const { return m_vertices; }
97
98	/// The vertices. Owned by this class.
99	b2Vec2* m_vertices;
100
101	/// The vertex count.
102	int32 m_count;
103
104	b2Vec2 m_prevVertex, m_nextVertex;
105	bool m_hasPrevVertex, m_hasNextVertex;
106};
107
108inline b2ChainShape::b2ChainShape()
109{
110	m_type = e_chain;
111	m_radius = b2_polygonRadius;
112	m_vertices = NULL;
113	m_count = 0;
114	m_hasPrevVertex = false;
115	m_hasNextVertex = false;
116}
117
118#endif
119