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[blok] / Box2D / Source / Collision / Shapes / b2PolygonShape.h

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+/*
+* Copyright (c) 2006-2007 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 "b2Shape.h"
+
+/// Convex polygon. The vertices must be in CCW order for a right-handed
+/// coordinate system with the z-axis coming out of the screen.
+struct b2PolygonDef : public b2ShapeDef
+{
+       b2PolygonDef()
+       {
+               type = e_polygonShape;
+               vertexCount = 0;
+       }
+
+       /// 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);
+
+       /// The polygon vertices in local coordinates.
+       b2Vec2 vertices[b2_maxPolygonVertices];
+
+       /// The number of polygon vertices.
+       int32 vertexCount;
+};
+
+
+/// A convex polygon.
+class b2PolygonShape : public b2Shape
+{
+public:
+       /// @see b2Shape::TestPoint
+       bool TestPoint(const b2XForm& transform, const b2Vec2& p) const;
+
+       /// @see b2Shape::TestSegment
+       bool TestSegment(       const b2XForm& transform,
+               float32* lambda,
+               b2Vec2* normal,
+               const b2Segment& segment,
+               float32 maxLambda) const;
+
+       /// @see b2Shape::ComputeAABB
+       void ComputeAABB(b2AABB* aabb, const b2XForm& transform) const;
+
+       /// @see b2Shape::ComputeSweptAABB
+       void ComputeSweptAABB(  b2AABB* aabb,
+               const b2XForm& transform1,
+               const b2XForm& transform2) const;
+
+       /// @see b2Shape::ComputeMass
+       void ComputeMass(b2MassData* massData) const;
+
+       /// Get the oriented bounding box relative to the parent body.
+       const b2OBB& GetOBB() const;
+
+       /// Get local centroid relative to the parent body.
+       const b2Vec2& GetCentroid() const;
+
+       /// Get the vertex count.
+       int32 GetVertexCount() const;
+
+       /// Get the vertices in local coordinates.
+       const b2Vec2* GetVertices() const;
+
+       /// Get the core vertices in local coordinates. These vertices
+       /// represent a smaller polygon that is used for time of impact
+       /// computations.
+       const b2Vec2* GetCoreVertices() const;
+
+       /// Get the edge normal vectors. There is one for each vertex.
+       const b2Vec2* GetNormals() const;
+
+       /// Get the first vertex and apply the supplied transform.
+       b2Vec2 GetFirstVertex(const b2XForm& xf) const;
+
+       /// Get the centroid and apply the supplied transform.
+       b2Vec2 Centroid(const b2XForm& xf) const;
+
+       /// Get the support point in the given world direction.
+       /// Use the supplied transform.
+       b2Vec2 Support(const b2XForm& xf, const b2Vec2& d) const;
+
+private:
+
+       friend class b2Shape;
+
+       b2PolygonShape(const b2ShapeDef* def);
+
+       void UpdateSweepRadius(const b2Vec2& center);
+
+       // Local position of the polygon centroid.
+       b2Vec2 m_centroid;
+
+       b2OBB m_obb;
+
+       b2Vec2 m_vertices[b2_maxPolygonVertices];
+       b2Vec2 m_normals[b2_maxPolygonVertices];
+       b2Vec2 m_coreVertices[b2_maxPolygonVertices];
+       int32 m_vertexCount;
+};
+
+inline b2Vec2 b2PolygonShape::GetFirstVertex(const b2XForm& xf) const
+{
+       return b2Mul(xf, m_coreVertices[0]);
+}
+
+inline const b2OBB& b2PolygonShape::GetOBB() const
+{
+       return m_obb;
+}
+
+inline const b2Vec2& b2PolygonShape::GetCentroid() const
+{
+       return m_centroid;
+}
+
+inline int32 b2PolygonShape::GetVertexCount() const
+{
+       return m_vertexCount;
+}
+
+inline const b2Vec2* b2PolygonShape::GetVertices() const
+{
+       return m_vertices;
+}
+
+inline const b2Vec2* b2PolygonShape::GetCoreVertices() const
+{
+       return m_coreVertices;
+}
+
+inline const b2Vec2* b2PolygonShape::GetNormals() const
+{
+       return m_normals;
+}
+
+#endif