text: /*
  * 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_SHAPE_H
  #define B2_SHAPE_H
  
  #include "b2BlockAllocator.h"
  #include "b2Math.h"
  #include "b2Collision.h"
  
  /// This holds the mass data computed for a shape.
  struct b2MassData
  {
  	/// The mass of the shape, usually in kilograms.
  	float32 mass;
  
  	/// The position of the shape's centroid relative to the shape's origin.
  	b2Vec2 center;
  
  	/// The rotational inertia of the shape about the local origin.
  	float32 I;
  };
  
  /// A shape is used for collision detection. You can create a shape however you like.
  /// Shapes used for simulation in b2World are created automatically when a b2Fixture
  /// is created.
  class b2Shape
  {
  public:
  	
  	enum Type
  	{
  		e_unknown= -1,
  		e_circle = 0,
  		e_polygon = 1,
  		e_typeCount = 2,
  	};
  
  	b2Shape() { m_type = e_unknown; }
  	virtual ~b2Shape() {}
  
  	/// Clone the concrete shape using the provided allocator.
  	virtual b2Shape* Clone(b2BlockAllocator* allocator) const = 0;
  
  	/// Get the type of this shape. You can use this to down cast to the concrete shape.
  	/// @return the shape type.
  	Type GetType() const;
  
  	/// Test a point for containment in this shape. This only works for convex shapes.
  	/// @param xf the shape world transform.
  	/// @param p a point in world coordinates.
  	virtual bool TestPoint(const b2Transform& xf, const b2Vec2& p) const = 0;
  
  	/// Cast a ray against this shape.
  	/// @param output the ray-cast results.
  	/// @param input the ray-cast input parameters.
  	/// @param transform the transform to be applied to the shape.
  	virtual bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input, const b2Transform& transform) const = 0;
  
  	/// Given a transform, compute the associated axis aligned bounding box for this shape.
  	/// @param aabb returns the axis aligned box.
  	/// @param xf the world transform of the shape.
  	virtual void ComputeAABB(b2AABB* aabb, const b2Transform& xf) const = 0;
  
  	/// Compute the mass properties of this shape using its dimensions and density.
  	/// The inertia tensor is computed about the local origin.
  	/// @param massData returns the mass data for this shape.
  	/// @param density the density in kilograms per meter squared.
  	virtual void ComputeMass(b2MassData* massData, float32 density) const = 0;
  
  	Type m_type;
  	float32 m_radius;
  };
  
  inline b2Shape::Type b2Shape::GetType() const
  {
  	return m_type;
  }
  
  #endif
  