1 /*
2 * Copyright (c) 2006-2009 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_POLYGON_SHAPE_H
20 #define B2_POLYGON_SHAPE_H
21
22 #include <Box2D/Collision/Shapes/b2Shape.h>
23
24 /// A convex polygon. It is assumed that the interior of the polygon is to
25 /// the left of each edge.
26 /// Polygons have a maximum number of vertices equal to b2_maxPolygonVertices.
27 /// In most cases you should not need many vertices for a convex polygon.
28 class b2PolygonShape : public b2Shape
29 {
30 public:
31 b2PolygonShape();
32
33 /// Implement b2Shape.
34 b2Shape* Clone(b2BlockAllocator* allocator) const;
35
36 /// @see b2Shape::GetChildCount
37 int32 GetChildCount() const;
38
39 /// Create a convex hull from the given array of local points.
40 /// The count must be in the range [3, b2_maxPolygonVertices].
41 /// @warning the points may be re-ordered, even if they form a convex polygon
42 /// @warning collinear points are handled but not removed. Collinear points
43 /// may lead to poor stacking behavior.
44 void Set(const b2Vec2* points, int32 count);
45
46 /// Build vertices to represent an axis-aligned box centered on the local origin.
47 /// @param hx the half-width.
48 /// @param hy the half-height.
49 void SetAsBox(float32 hx, float32 hy);
50
51 /// Build vertices to represent an oriented box.
52 /// @param hx the half-width.
53 /// @param hy the half-height.
54 /// @param center the center of the box in local coordinates.
55 /// @param angle the rotation of the box in local coordinates.
56 void SetAsBox(float32 hx, float32 hy, const b2Vec2& center, float32 angle);
57
58 /// @see b2Shape::TestPoint
59 bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
60
61 /// Implement b2Shape.
62 bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
63 const b2Transform& transform, int32 childIndex) const;
64
65 /// @see b2Shape::ComputeAABB
66 void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const;
67
68 /// @see b2Shape::ComputeMass
69 void ComputeMass(b2MassData* massData, float32 density) const;
70
71 /// Get the vertex count.
GetVertexCount()72 int32 GetVertexCount() const { return m_count; }
73
74 /// Get a vertex by index.
75 const b2Vec2& GetVertex(int32 index) const;
76
77 /// Validate convexity. This is a very time consuming operation.
78 /// @returns true if valid
79 bool Validate() const;
80
81 b2Vec2 m_centroid;
82 b2Vec2 m_vertices[b2_maxPolygonVertices];
83 b2Vec2 m_normals[b2_maxPolygonVertices];
84 int32 m_count;
85 };
86
b2PolygonShape()87 inline b2PolygonShape::b2PolygonShape()
88 {
89 m_type = e_polygon;
90 m_radius = b2_polygonRadius;
91 m_count = 0;
92 m_centroid.SetZero();
93 }
94
GetVertex(int32 index)95 inline const b2Vec2& b2PolygonShape::GetVertex(int32 index) const
96 {
97 b2Assert(0 <= index && index < m_count);
98 return m_vertices[index];
99 }
100
101 #endif
102