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 /// The vertices. Owned by this class.
86 b2Vec2* m_vertices;
87
88 /// The vertex count.
89 int32 m_count;
90
91 b2Vec2 m_prevVertex, m_nextVertex;
92 bool m_hasPrevVertex, m_hasNextVertex;
93};
94
95inline b2ChainShape::b2ChainShape()
96{
97 m_type = e_chain;
98 m_radius = b2_polygonRadius;
99 m_vertices = NULL;
100 m_count = 0;
101 m_hasPrevVertex = false;
102 m_hasNextVertex = false;
103}
104
105#endif
106