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
24 class 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.
32 class b2ChainShape : public b2Shape
33 {
34 public:
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.
GetVertexCount()86 int32 GetVertexCount() const { return m_count; }
87
88 /// Get the vertices (read-only).
GetVertex(int32 index)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).
GetVertices()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
b2ChainShape()108 inline 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