b2PolygonShape.h
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上传日期:2022-01-07
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- /*
- * Copyright (c) 2006-2009 Erin Catto http://www.gphysics.com
- *
- * This software is provided 'as-is', without any express or implied
- * warranty. In no event will the authors be held liable for any damages
- * arising from the use of this software.
- * Permission is granted to anyone to use this software for any purpose,
- * including commercial applications, and to alter it and redistribute it
- * freely, subject to the following restrictions:
- * 1. The origin of this software must not be misrepresented; you must not
- * claim that you wrote the original software. If you use this software
- * in a product, an acknowledgment in the product documentation would be
- * appreciated but is not required.
- * 2. Altered source versions must be plainly marked as such, and must not be
- * misrepresented as being the original software.
- * 3. This notice may not be removed or altered from any source distribution.
- */
- #ifndef B2_POLYGON_SHAPE_H
- #define B2_POLYGON_SHAPE_H
- #include <Box2D/Collision/Shapes/b2Shape.h>
- /// A convex polygon. It is assumed that the interior of the polygon is to
- /// the left of each edge.
- class b2PolygonShape : public b2Shape
- {
- public:
- b2PolygonShape();
- /// Implement b2Shape.
- b2Shape* Clone(b2BlockAllocator* allocator) const;
- /// Copy vertices. This assumes the vertices define a convex polygon.
- /// It is assumed that the exterior is the the right of each edge.
- void Set(const b2Vec2* vertices, int32 vertexCount);
- /// Build vertices to represent an axis-aligned box.
- /// @param hx the half-width.
- /// @param hy the half-height.
- void SetAsBox(float32 hx, float32 hy);
- /// Build vertices to represent an oriented box.
- /// @param hx the half-width.
- /// @param hy the half-height.
- /// @param center the center of the box in local coordinates.
- /// @param angle the rotation of the box in local coordinates.
- void SetAsBox(float32 hx, float32 hy, const b2Vec2& center, float32 angle);
- /// Set this as a single edge.
- void SetAsEdge(const b2Vec2& v1, const b2Vec2& v2);
- /// @see b2Shape::TestPoint
- bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
- /// Implement b2Shape.
- bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input, const b2Transform& transform) const;
- /// @see b2Shape::ComputeAABB
- void ComputeAABB(b2AABB* aabb, const b2Transform& transform) const;
- /// @see b2Shape::ComputeMass
- void ComputeMass(b2MassData* massData, float32 density) const;
- /// Get the supporting vertex index in the given direction.
- int32 GetSupport(const b2Vec2& d) const;
- /// Get the supporting vertex in the given direction.
- const b2Vec2& GetSupportVertex(const b2Vec2& d) const;
- /// Get the vertex count.
- int32 GetVertexCount() const { return m_vertexCount; }
- /// Get a vertex by index.
- const b2Vec2& GetVertex(int32 index) const;
- b2Vec2 m_centroid;
- b2Vec2 m_vertices[b2_maxPolygonVertices];
- b2Vec2 m_normals[b2_maxPolygonVertices];
- int32 m_vertexCount;
- };
- inline b2PolygonShape::b2PolygonShape()
- {
- m_type = e_polygon;
- m_radius = b2_polygonRadius;
- m_vertexCount = 0;
- m_centroid.SetZero();
- }
- inline int32 b2PolygonShape::GetSupport(const b2Vec2& d) const
- {
- int32 bestIndex = 0;
- float32 bestValue = b2Dot(m_vertices[0], d);
- for (int32 i = 1; i < m_vertexCount; ++i)
- {
- float32 value = b2Dot(m_vertices[i], d);
- if (value > bestValue)
- {
- bestIndex = i;
- bestValue = value;
- }
- }
- return bestIndex;
- }
- inline const b2Vec2& b2PolygonShape::GetSupportVertex(const b2Vec2& d) const
- {
- int32 bestIndex = 0;
- float32 bestValue = b2Dot(m_vertices[0], d);
- for (int32 i = 1; i < m_vertexCount; ++i)
- {
- float32 value = b2Dot(m_vertices[i], d);
- if (value > bestValue)
- {
- bestIndex = i;
- bestValue = value;
- }
- }
- return m_vertices[bestIndex];
- }
- inline const b2Vec2& b2PolygonShape::GetVertex(int32 index) const
- {
- b2Assert(0 <= index && index < m_vertexCount);
- return m_vertices[index];
- }
- #endif