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inc/Box2D/Collision/Shapes/b2ChainShape.h

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+/*
+* Copyright (c) 2006-2010 Erin Catto http://www.box2d.org
+*
+* 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_CHAIN_SHAPE_H
+#define B2_CHAIN_SHAPE_H
+
+#include <Box2D/Collision/Shapes/b2Shape.h>
+
+class b2EdgeShape;
+
+/// A chain shape is a free form sequence of line segments.
+/// The chain has two-sided collision, so you can use inside and outside collision.
+/// Therefore, you may use any winding order.
+/// Since there may be many vertices, they are allocated using b2Alloc.
+/// Connectivity information is used to create smooth collisions.
+/// WARNING: The chain will not collide properly if there are self-intersections.
+class b2ChainShape : public b2Shape
+{
+public:
+	b2ChainShape();
+
+	/// The destructor frees the vertices using b2Free.
+	~b2ChainShape();
+
+	/// Clear all data.
+	void Clear();
+
+	/// Create a loop. This automatically adjusts connectivity.
+	/// @param vertices an array of vertices, these are copied
+	/// @param count the vertex count
+	void CreateLoop(const b2Vec2* vertices, int32 count);
+
+	/// Create a chain with isolated end vertices.
+	/// @param vertices an array of vertices, these are copied
+	/// @param count the vertex count
+	void CreateChain(const b2Vec2* vertices, int32 count);
+
+	/// Establish connectivity to a vertex that precedes the first vertex.
+	/// Don't call this for loops.
+	void SetPrevVertex(const b2Vec2& prevVertex);
+
+	/// Establish connectivity to a vertex that follows the last vertex.
+	/// Don't call this for loops.
+	void SetNextVertex(const b2Vec2& nextVertex);
+
+	/// Implement b2Shape. Vertices are cloned using b2Alloc.
+	b2Shape* Clone(b2BlockAllocator* allocator) const;
+
+	/// @see b2Shape::GetChildCount
+	int32 GetChildCount() const;
+
+	/// Get a child edge.
+	void GetChildEdge(b2EdgeShape* edge, int32 index) const;
+
+	/// This always return false.
+	/// @see b2Shape::TestPoint
+	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
+
+	/// Implement b2Shape.
+	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+					const b2Transform& transform, int32 childIndex) const;
+
+	/// @see b2Shape::ComputeAABB
+	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const;
+
+	/// Chains have zero mass.
+	/// @see b2Shape::ComputeMass
+	void ComputeMass(b2MassData* massData, float32 density) const;
+
+	/// The vertices. Owned by this class.
+	b2Vec2* m_vertices;
+
+	/// The vertex count.
+	int32 m_count;
+
+	b2Vec2 m_prevVertex, m_nextVertex;
+	bool m_hasPrevVertex, m_hasNextVertex;
+};
+
+inline b2ChainShape::b2ChainShape()
+{
+	m_type = e_chain;
+	m_radius = b2_polygonRadius;
+	m_vertices = NULL;
+	m_count = 0;
+	m_hasPrevVertex = false;
+	m_hasNextVertex = false;
+}
+
+#endif

inc/Box2D/Collision/Shapes/b2CircleShape.h

@@ -0,0 +1,91 @@
+/*
+* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
+*
+* 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_CIRCLE_SHAPE_H
+#define B2_CIRCLE_SHAPE_H
+
+#include <Box2D/Collision/Shapes/b2Shape.h>
+
+/// A circle shape.
+class b2CircleShape : public b2Shape
+{
+public:
+	b2CircleShape();
+
+	/// Implement b2Shape.
+	b2Shape* Clone(b2BlockAllocator* allocator) const;
+
+	/// @see b2Shape::GetChildCount
+	int32 GetChildCount() const;
+
+	/// Implement b2Shape.
+	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
+
+	/// Implement b2Shape.
+	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+				const b2Transform& transform, int32 childIndex) const;
+
+	/// @see b2Shape::ComputeAABB
+	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) 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 1; }
+
+	/// Get a vertex by index. Used by b2Distance.
+	const b2Vec2& GetVertex(int32 index) const;
+
+	/// Position
+	b2Vec2 m_p;
+};
+
+inline b2CircleShape::b2CircleShape()
+{
+	m_type = e_circle;
+	m_radius = 0.0f;
+	m_p.SetZero();
+}
+
+inline int32 b2CircleShape::GetSupport(const b2Vec2 &d) const
+{
+	B2_NOT_USED(d);
+	return 0;
+}
+
+inline const b2Vec2& b2CircleShape::GetSupportVertex(const b2Vec2 &d) const
+{
+	B2_NOT_USED(d);
+	return m_p;
+}
+
+inline const b2Vec2& b2CircleShape::GetVertex(int32 index) const
+{
+	B2_NOT_USED(index);
+	b2Assert(index == 0);
+	return m_p;
+}
+
+#endif

inc/Box2D/Collision/Shapes/b2EdgeShape.h

@@ -0,0 +1,74 @@
+/*
+* Copyright (c) 2006-2010 Erin Catto http://www.box2d.org
+*
+* 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_EDGE_SHAPE_H
+#define B2_EDGE_SHAPE_H
+
+#include <Box2D/Collision/Shapes/b2Shape.h>
+
+/// A line segment (edge) shape. These can be connected in chains or loops
+/// to other edge shapes. The connectivity information is used to ensure
+/// correct contact normals.
+class b2EdgeShape : public b2Shape
+{
+public:
+	b2EdgeShape();
+
+	/// Set this as an isolated edge.
+	void Set(const b2Vec2& v1, const b2Vec2& v2);
+
+	/// Implement b2Shape.
+	b2Shape* Clone(b2BlockAllocator* allocator) const;
+
+	/// @see b2Shape::GetChildCount
+	int32 GetChildCount() const;
+
+	/// @see b2Shape::TestPoint
+	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
+
+	/// Implement b2Shape.
+	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+				const b2Transform& transform, int32 childIndex) const;
+
+	/// @see b2Shape::ComputeAABB
+	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const;
+
+	/// @see b2Shape::ComputeMass
+	void ComputeMass(b2MassData* massData, float32 density) const;
+	
+	/// These are the edge vertices
+	b2Vec2 m_vertex1, m_vertex2;
+
+	/// Optional adjacent vertices. These are used for smooth collision.
+	b2Vec2 m_vertex0, m_vertex3;
+	bool m_hasVertex0, m_hasVertex3;
+};
+
+inline b2EdgeShape::b2EdgeShape()
+{
+	m_type = e_edge;
+	m_radius = b2_polygonRadius;
+	m_vertex0.x = 0.0f;
+	m_vertex0.y = 0.0f;
+	m_vertex3.x = 0.0f;
+	m_vertex3.y = 0.0f;
+	m_hasVertex0 = false;
+	m_hasVertex3 = false;
+}
+
+#endif

inc/Box2D/Collision/Shapes/b2PolygonShape.h

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+/*
+* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
+*
+* 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.
+/// Polygons have a maximum number of vertices equal to b2_maxPolygonVertices.
+/// In most cases you should not need many vertices for a convex polygon.
+class b2PolygonShape : public b2Shape
+{
+public:
+	b2PolygonShape();
+
+	/// Implement b2Shape.
+	b2Shape* Clone(b2BlockAllocator* allocator) const;
+
+	/// @see b2Shape::GetChildCount
+	int32 GetChildCount() const;
+
+	/// Create a convex hull from the given array of local points.
+	/// The count must be in the range [3, b2_maxPolygonVertices].
+	/// @warning the points may be re-ordered, even if they form a convex polygon
+	/// @warning collinear points are handled but not removed. Collinear points
+	/// may lead to poor stacking behavior.
+	void Set(const b2Vec2* points, int32 count);
+
+	/// Build vertices to represent an axis-aligned box centered on the local origin.
+	/// @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);
+
+	/// @see b2Shape::TestPoint
+	bool TestPoint(const b2Transform& transform, const b2Vec2& p) const;
+
+	/// Implement b2Shape.
+	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+					const b2Transform& transform, int32 childIndex) const;
+
+	/// @see b2Shape::ComputeAABB
+	void ComputeAABB(b2AABB* aabb, const b2Transform& transform, int32 childIndex) const;
+
+	/// @see b2Shape::ComputeMass
+	void ComputeMass(b2MassData* massData, float32 density) const;
+
+	/// Get the vertex count.
+	int32 GetVertexCount() const { return m_count; }
+
+	/// Get a vertex by index.
+	const b2Vec2& GetVertex(int32 index) const;
+
+	/// Validate convexity. This is a very time consuming operation.
+	/// @returns true if valid
+	bool Validate() const;
+
+	b2Vec2 m_centroid;
+	b2Vec2 m_vertices[b2_maxPolygonVertices];
+	b2Vec2 m_normals[b2_maxPolygonVertices];
+	int32 m_count;
+};
+
+inline b2PolygonShape::b2PolygonShape()
+{
+	m_type = e_polygon;
+	m_radius = b2_polygonRadius;
+	m_count = 0;
+	m_centroid.SetZero();
+}
+
+inline const b2Vec2& b2PolygonShape::GetVertex(int32 index) const
+{
+	b2Assert(0 <= index && index < m_count);
+	return m_vertices[index];
+}
+
+#endif

inc/Box2D/Collision/Shapes/b2Shape.h

@@ -0,0 +1,101 @@
+/*
+* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
+*
+* 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 <Box2D/Common/b2BlockAllocator.h>
+#include <Box2D/Common/b2Math.h>
+#include <Box2D/Collision/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. Shapes may encapsulate a one or more child shapes.
+class b2Shape
+{
+public:
+	
+	enum Type
+	{
+		e_circle = 0,
+		e_edge = 1,
+		e_polygon = 2,
+		e_chain = 3,
+		e_typeCount = 4
+	};
+
+	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;
+
+	/// Get the number of child primitives.
+	virtual int32 GetChildCount() const = 0;
+
+	/// 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 a child shape.
+	/// @param output the ray-cast results.
+	/// @param input the ray-cast input parameters.
+	/// @param transform the transform to be applied to the shape.
+	/// @param childIndex the child shape index
+	virtual bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input,
+						const b2Transform& transform, int32 childIndex) const = 0;
+
+	/// Given a transform, compute the associated axis aligned bounding box for a child shape.
+	/// @param aabb returns the axis aligned box.
+	/// @param xf the world transform of the shape.
+	/// @param childIndex the child shape
+	virtual void ComputeAABB(b2AABB* aabb, const b2Transform& xf, int32 childIndex) 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

inc/Box2D/Collision/b2BroadPhase.h

@@ -0,0 +1,257 @@
+/*
+* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
+*
+* 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_BROAD_PHASE_H
+#define B2_BROAD_PHASE_H
+
+#include <Box2D/Common/b2Settings.h>
+#include <Box2D/Collision/b2Collision.h>
+#include <Box2D/Collision/b2DynamicTree.h>
+#include <algorithm>
+
+struct b2Pair
+{
+	int32 proxyIdA;
+	int32 proxyIdB;
+};
+
+/// The broad-phase is used for computing pairs and performing volume queries and ray casts.
+/// This broad-phase does not persist pairs. Instead, this reports potentially new pairs.
+/// It is up to the client to consume the new pairs and to track subsequent overlap.
+class b2BroadPhase
+{
+public:
+
+	enum
+	{
+		e_nullProxy = -1
+	};
+
+	b2BroadPhase();
+	~b2BroadPhase();
+
+	/// Create a proxy with an initial AABB. Pairs are not reported until
+	/// UpdatePairs is called.
+	int32 CreateProxy(const b2AABB& aabb, void* userData);
+
+	/// Destroy a proxy. It is up to the client to remove any pairs.
+	void DestroyProxy(int32 proxyId);
+
+	/// Call MoveProxy as many times as you like, then when you are done
+	/// call UpdatePairs to finalized the proxy pairs (for your time step).
+	void MoveProxy(int32 proxyId, const b2AABB& aabb, const b2Vec2& displacement);
+
+	/// Call to trigger a re-processing of it's pairs on the next call to UpdatePairs.
+	void TouchProxy(int32 proxyId);
+
+	/// Get the fat AABB for a proxy.
+	const b2AABB& GetFatAABB(int32 proxyId) const;
+
+	/// Get user data from a proxy. Returns NULL if the id is invalid.
+	void* GetUserData(int32 proxyId) const;
+
+	/// Test overlap of fat AABBs.
+	bool TestOverlap(int32 proxyIdA, int32 proxyIdB) const;
+
+	/// Get the number of proxies.
+	int32 GetProxyCount() const;
+
+	/// Update the pairs. This results in pair callbacks. This can only add pairs.
+	template <typename T>
+	void UpdatePairs(T* callback);
+
+	/// Query an AABB for overlapping proxies. The callback class
+	/// is called for each proxy that overlaps the supplied AABB.
+	template <typename T>
+	void Query(T* callback, const b2AABB& aabb) const;
+
+	/// Ray-cast against the proxies in the tree. This relies on the callback
+	/// to perform a exact ray-cast in the case were the proxy contains a shape.
+	/// The callback also performs the any collision filtering. This has performance
+	/// roughly equal to k * log(n), where k is the number of collisions and n is the
+	/// number of proxies in the tree.
+	/// @param input the ray-cast input data. The ray extends from p1 to p1 + maxFraction * (p2 - p1).
+	/// @param callback a callback class that is called for each proxy that is hit by the ray.
+	template <typename T>
+	void RayCast(T* callback, const b2RayCastInput& input) const;
+
+	/// Get the height of the embedded tree.
+	int32 GetTreeHeight() const;
+
+	/// Get the balance of the embedded tree.
+	int32 GetTreeBalance() const;
+
+	/// Get the quality metric of the embedded tree.
+	float32 GetTreeQuality() const;
+
+	/// Shift the world origin. Useful for large worlds.
+	/// The shift formula is: position -= newOrigin
+	/// @param newOrigin the new origin with respect to the old origin
+	void ShiftOrigin(const b2Vec2& newOrigin);
+
+private:
+
+	friend class b2DynamicTree;
+
+	void BufferMove(int32 proxyId);
+	void UnBufferMove(int32 proxyId);
+
+	bool QueryCallback(int32 proxyId);
+
+	b2DynamicTree m_tree;
+
+	int32 m_proxyCount;
+
+	int32* m_moveBuffer;
+	int32 m_moveCapacity;
+	int32 m_moveCount;
+
+	b2Pair* m_pairBuffer;
+	int32 m_pairCapacity;
+	int32 m_pairCount;
+
+	int32 m_queryProxyId;
+};
+
+/// This is used to sort pairs.
+inline bool b2PairLessThan(const b2Pair& pair1, const b2Pair& pair2)
+{
+	if (pair1.proxyIdA < pair2.proxyIdA)
+	{
+		return true;
+	}
+
+	if (pair1.proxyIdA == pair2.proxyIdA)
+	{
+		return pair1.proxyIdB < pair2.proxyIdB;
+	}
+
+	return false;
+}
+
+inline void* b2BroadPhase::GetUserData(int32 proxyId) const
+{
+	return m_tree.GetUserData(proxyId);
+}
+
+inline bool b2BroadPhase::TestOverlap(int32 proxyIdA, int32 proxyIdB) const
+{
+	const b2AABB& aabbA = m_tree.GetFatAABB(proxyIdA);
+	const b2AABB& aabbB = m_tree.GetFatAABB(proxyIdB);
+	return b2TestOverlap(aabbA, aabbB);
+}
+
+inline const b2AABB& b2BroadPhase::GetFatAABB(int32 proxyId) const
+{
+	return m_tree.GetFatAABB(proxyId);
+}
+
+inline int32 b2BroadPhase::GetProxyCount() const
+{
+	return m_proxyCount;
+}
+
+inline int32 b2BroadPhase::GetTreeHeight() const
+{
+	return m_tree.GetHeight();
+}
+
+inline int32 b2BroadPhase::GetTreeBalance() const
+{
+	return m_tree.GetMaxBalance();
+}
+
+inline float32 b2BroadPhase::GetTreeQuality() const
+{
+	return m_tree.GetAreaRatio();
+}
+
+template <typename T>
+void b2BroadPhase::UpdatePairs(T* callback)
+{
+	// Reset pair buffer
+	m_pairCount = 0;
+
+	// Perform tree queries for all moving proxies.
+	for (int32 i = 0; i < m_moveCount; ++i)
+	{
+		m_queryProxyId = m_moveBuffer[i];
+		if (m_queryProxyId == e_nullProxy)
+		{
+			continue;
+		}
+
+		// We have to query the tree with the fat AABB so that
+		// we don't fail to create a pair that may touch later.
+		const b2AABB& fatAABB = m_tree.GetFatAABB(m_queryProxyId);
+
+		// Query tree, create pairs and add them pair buffer.
+		m_tree.Query(this, fatAABB);
+	}
+
+	// Reset move buffer
+	m_moveCount = 0;
+
+	// Sort the pair buffer to expose duplicates.
+	std::sort(m_pairBuffer, m_pairBuffer + m_pairCount, b2PairLessThan);
+
+	// Send the pairs back to the client.
+	int32 i = 0;
+	while (i < m_pairCount)
+	{
+		b2Pair* primaryPair = m_pairBuffer + i;
+		void* userDataA = m_tree.GetUserData(primaryPair->proxyIdA);
+		void* userDataB = m_tree.GetUserData(primaryPair->proxyIdB);
+
+		callback->AddPair(userDataA, userDataB);
+		++i;
+
+		// Skip any duplicate pairs.
+		while (i < m_pairCount)
+		{
+			b2Pair* pair = m_pairBuffer + i;
+			if (pair->proxyIdA != primaryPair->proxyIdA || pair->proxyIdB != primaryPair->proxyIdB)
+			{
+				break;
+			}
+			++i;
+		}
+	}
+
+	// Try to keep the tree balanced.
+	//m_tree.Rebalance(4);
+}
+
+template <typename T>
+inline void b2BroadPhase::Query(T* callback, const b2AABB& aabb) const
+{
+	m_tree.Query(callback, aabb);
+}
+
+template <typename T>
+inline void b2BroadPhase::RayCast(T* callback, const b2RayCastInput& input) const
+{
+	m_tree.RayCast(callback, input);
+}
+
+inline void b2BroadPhase::ShiftOrigin(const b2Vec2& newOrigin)
+{
+	m_tree.ShiftOrigin(newOrigin);
+}
+
+#endif

inc/Box2D/Collision/b2Collision.h

@@ -0,0 +1,277 @@
+/*
+* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
+*
+* 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_COLLISION_H
+#define B2_COLLISION_H
+
+#include <Box2D/Common/b2Math.h>
+#include <limits.h>
+
+/// @file
+/// Structures and functions used for computing contact points, distance
+/// queries, and TOI queries.
+
+class b2Shape;
+class b2CircleShape;
+class b2EdgeShape;
+class b2PolygonShape;
+
+const uint8 b2_nullFeature = UCHAR_MAX;
+
+/// The features that intersect to form the contact point
+/// This must be 4 bytes or less.
+struct b2ContactFeature
+{
+	enum Type
+	{
+		e_vertex = 0,
+		e_face = 1
+	};
+
+	uint8 indexA;		///< Feature index on shapeA
+	uint8 indexB;		///< Feature index on shapeB
+	uint8 typeA;		///< The feature type on shapeA
+	uint8 typeB;		///< The feature type on shapeB
+};
+
+/// Contact ids to facilitate warm starting.
+union b2ContactID
+{
+	b2ContactFeature cf;
+	uint32 key;					///< Used to quickly compare contact ids.
+};
+
+/// A manifold point is a contact point belonging to a contact
+/// manifold. It holds details related to the geometry and dynamics
+/// of the contact points.
+/// The local point usage depends on the manifold type:
+/// -e_circles: the local center of circleB
+/// -e_faceA: the local center of cirlceB or the clip point of polygonB
+/// -e_faceB: the clip point of polygonA
+/// This structure is stored across time steps, so we keep it small.
+/// Note: the impulses are used for internal caching and may not
+/// provide reliable contact forces, especially for high speed collisions.
+struct b2ManifoldPoint
+{
+	b2Vec2 localPoint;		///< usage depends on manifold type
+	float32 normalImpulse;	///< the non-penetration impulse
+	float32 tangentImpulse;	///< the friction impulse
+	b2ContactID id;			///< uniquely identifies a contact point between two shapes
+};
+
+/// A manifold for two touching convex shapes.
+/// Box2D supports multiple types of contact:
+/// - clip point versus plane with radius
+/// - point versus point with radius (circles)
+/// The local point usage depends on the manifold type:
+/// -e_circles: the local center of circleA
+/// -e_faceA: the center of faceA
+/// -e_faceB: the center of faceB
+/// Similarly the local normal usage:
+/// -e_circles: not used
+/// -e_faceA: the normal on polygonA
+/// -e_faceB: the normal on polygonB
+/// We store contacts in this way so that position correction can
+/// account for movement, which is critical for continuous physics.
+/// All contact scenarios must be expressed in one of these types.
+/// This structure is stored across time steps, so we keep it small.
+struct b2Manifold
+{
+	enum Type
+	{
+		e_circles,
+		e_faceA,
+		e_faceB
+	};
+
+	b2ManifoldPoint points[b2_maxManifoldPoints];	///< the points of contact
+	b2Vec2 localNormal;								///< not use for Type::e_points
+	b2Vec2 localPoint;								///< usage depends on manifold type
+	Type type;
+	int32 pointCount;								///< the number of manifold points
+};
+
+/// This is used to compute the current state of a contact manifold.
+struct b2WorldManifold
+{
+	/// Evaluate the manifold with supplied transforms. This assumes
+	/// modest motion from the original state. This does not change the
+	/// point count, impulses, etc. The radii must come from the shapes
+	/// that generated the manifold.
+	void Initialize(const b2Manifold* manifold,
+					const b2Transform& xfA, float32 radiusA,
+					const b2Transform& xfB, float32 radiusB);
+
+	b2Vec2 normal;								///< world vector pointing from A to B
+	b2Vec2 points[b2_maxManifoldPoints];		///< world contact point (point of intersection)
+	float32 separations[b2_maxManifoldPoints];	///< a negative value indicates overlap, in meters
+};
+
+/// This is used for determining the state of contact points.
+enum b2PointState
+{
+	b2_nullState,		///< point does not exist
+	b2_addState,		///< point was added in the update
+	b2_persistState,	///< point persisted across the update
+	b2_removeState		///< point was removed in the update
+};
+
+/// Compute the point states given two manifolds. The states pertain to the transition from manifold1
+/// to manifold2. So state1 is either persist or remove while state2 is either add or persist.
+void b2GetPointStates(b2PointState state1[b2_maxManifoldPoints], b2PointState state2[b2_maxManifoldPoints],
+					  const b2Manifold* manifold1, const b2Manifold* manifold2);
+
+/// Used for computing contact manifolds.
+struct b2ClipVertex
+{
+	b2Vec2 v;
+	b2ContactID id;
+};
+
+/// Ray-cast input data. The ray extends from p1 to p1 + maxFraction * (p2 - p1).
+struct b2RayCastInput
+{
+	b2Vec2 p1, p2;
+	float32 maxFraction;
+};
+
+/// Ray-cast output data. The ray hits at p1 + fraction * (p2 - p1), where p1 and p2
+/// come from b2RayCastInput.
+struct b2RayCastOutput
+{
+	b2Vec2 normal;
+	float32 fraction;
+};
+
+/// An axis aligned bounding box.
+struct b2AABB
+{
+	/// Verify that the bounds are sorted.
+	bool IsValid() const;
+
+	/// Get the center of the AABB.
+	b2Vec2 GetCenter() const
+	{
+		return 0.5f * (lowerBound + upperBound);
+	}
+
+	/// Get the extents of the AABB (half-widths).
+	b2Vec2 GetExtents() const
+	{
+		return 0.5f * (upperBound - lowerBound);
+	}
+
+	/// Get the perimeter length
+	float32 GetPerimeter() const
+	{
+		float32 wx = upperBound.x - lowerBound.x;
+		float32 wy = upperBound.y - lowerBound.y;
+		return 2.0f * (wx + wy);
+	}
+
+	/// Combine an AABB into this one.
+	void Combine(const b2AABB& aabb)
+	{
+		lowerBound = b2Min(lowerBound, aabb.lowerBound);
+		upperBound = b2Max(upperBound, aabb.upperBound);
+	}
+
+	/// Combine two AABBs into this one.
+	void Combine(const b2AABB& aabb1, const b2AABB& aabb2)
+	{
+		lowerBound = b2Min(aabb1.lowerBound, aabb2.lowerBound);
+		upperBound = b2Max(aabb1.upperBound, aabb2.upperBound);
+	}
+
+	/// Does this aabb contain the provided AABB.
+	bool Contains(const b2AABB& aabb) const
+	{
+		bool result = true;
+		result = result && lowerBound.x <= aabb.lowerBound.x;
+		result = result && lowerBound.y <= aabb.lowerBound.y;
+		result = result && aabb.upperBound.x <= upperBound.x;
+		result = result && aabb.upperBound.y <= upperBound.y;
+		return result;
+	}
+
+	bool RayCast(b2RayCastOutput* output, const b2RayCastInput& input) const;
+
+	b2Vec2 lowerBound;	///< the lower vertex
+	b2Vec2 upperBound;	///< the upper vertex
+};
+
+/// Compute the collision manifold between two circles.
+void b2CollideCircles(b2Manifold* manifold,
+					  const b2CircleShape* circleA, const b2Transform& xfA,
+					  const b2CircleShape* circleB, const b2Transform& xfB);
+
+/// Compute the collision manifold between a polygon and a circle.
+void b2CollidePolygonAndCircle(b2Manifold* manifold,
+							   const b2PolygonShape* polygonA, const b2Transform& xfA,
+							   const b2CircleShape* circleB, const b2Transform& xfB);
+
+/// Compute the collision manifold between two polygons.
+void b2CollidePolygons(b2Manifold* manifold,
+					   const b2PolygonShape* polygonA, const b2Transform& xfA,
+					   const b2PolygonShape* polygonB, const b2Transform& xfB);
+
+/// Compute the collision manifold between an edge and a circle.
+void b2CollideEdgeAndCircle(b2Manifold* manifold,
+							   const b2EdgeShape* polygonA, const b2Transform& xfA,
+							   const b2CircleShape* circleB, const b2Transform& xfB);
+
+/// Compute the collision manifold between an edge and a circle.
+void b2CollideEdgeAndPolygon(b2Manifold* manifold,
+							   const b2EdgeShape* edgeA, const b2Transform& xfA,
+							   const b2PolygonShape* circleB, const b2Transform& xfB);
+
+/// Clipping for contact manifolds.
+int32 b2ClipSegmentToLine(b2ClipVertex vOut[2], const b2ClipVertex vIn[2],
+							const b2Vec2& normal, float32 offset, int32 vertexIndexA);
+
+/// Determine if two generic shapes overlap.
+bool b2TestOverlap(	const b2Shape* shapeA, int32 indexA,
+					const b2Shape* shapeB, int32 indexB,
+					const b2Transform& xfA, const b2Transform& xfB);
+
+// ---------------- Inline Functions ------------------------------------------
+
+inline bool b2AABB::IsValid() const
+{
+	b2Vec2 d = upperBound - lowerBound;
+	bool valid = d.x >= 0.0f && d.y >= 0.0f;
+	valid = valid && lowerBound.IsValid() && upperBound.IsValid();
+	return valid;
+}
+
+inline bool b2TestOverlap(const b2AABB& a, const b2AABB& b)
+{
+	b2Vec2 d1, d2;
+	d1 = b.lowerBound - a.upperBound;
+	d2 = a.lowerBound - b.upperBound;
+
+	if (d1.x > 0.0f || d1.y > 0.0f)
+		return false;
+
+	if (d2.x > 0.0f || d2.y > 0.0f)
+		return false;
+
+	return true;
+}
+
+#endif

inc/Box2D/Collision/b2Distance.h

@@ -0,0 +1,141 @@
+
+/*
+* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
+*
+* 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_DISTANCE_H
+#define B2_DISTANCE_H
+
+#include <Box2D/Common/b2Math.h>
+
+class b2Shape;
+
+/// A distance proxy is used by the GJK algorithm.
+/// It encapsulates any shape.
+struct b2DistanceProxy
+{
+	b2DistanceProxy() : m_vertices(NULL), m_count(0), m_radius(0.0f) {}
+
+	/// Initialize the proxy using the given shape. The shape
+	/// must remain in scope while the proxy is in use.
+	void Set(const b2Shape* shape, int32 index);
+
+	/// 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;
+
+	/// Get a vertex by index. Used by b2Distance.
+	const b2Vec2& GetVertex(int32 index) const;
+
+	b2Vec2 m_buffer[2];
+	const b2Vec2* m_vertices;
+	int32 m_count;
+	float32 m_radius;
+};
+
+/// Used to warm start b2Distance.
+/// Set count to zero on first call.
+struct b2SimplexCache
+{
+	float32 metric;		///< length or area
+	uint16 count;
+	uint8 indexA[3];	///< vertices on shape A
+	uint8 indexB[3];	///< vertices on shape B
+};
+
+/// Input for b2Distance.
+/// You have to option to use the shape radii
+/// in the computation. Even 
+struct b2DistanceInput
+{
+	b2DistanceProxy proxyA;
+	b2DistanceProxy proxyB;
+	b2Transform transformA;
+	b2Transform transformB;
+	bool useRadii;
+};
+
+/// Output for b2Distance.
+struct b2DistanceOutput
+{
+	b2Vec2 pointA;		///< closest point on shapeA
+	b2Vec2 pointB;		///< closest point on shapeB
+	float32 distance;
+	int32 iterations;	///< number of GJK iterations used
+};
+
+/// Compute the closest points between two shapes. Supports any combination of:
+/// b2CircleShape, b2PolygonShape, b2EdgeShape. The simplex cache is input/output.
+/// On the first call set b2SimplexCache.count to zero.
+void b2Distance(b2DistanceOutput* output,
+				b2SimplexCache* cache, 
+				const b2DistanceInput* input);
+
+
+//////////////////////////////////////////////////////////////////////////
+
+inline int32 b2DistanceProxy::GetVertexCount() const
+{
+	return m_count;
+}
+
+inline const b2Vec2& b2DistanceProxy::GetVertex(int32 index) const
+{
+	b2Assert(0 <= index && index < m_count);
+	return m_vertices[index];
+}
+
+inline int32 b2DistanceProxy::GetSupport(const b2Vec2& d) const
+{
+	int32 bestIndex = 0;
+	float32 bestValue = b2Dot(m_vertices[0], d);
+	for (int32 i = 1; i < m_count; ++i)
+	{
+		float32 value = b2Dot(m_vertices[i], d);
+		if (value > bestValue)
+		{
+			bestIndex = i;
+			bestValue = value;
+		}
+	}
+
+	return bestIndex;
+}
+
+inline const b2Vec2& b2DistanceProxy::GetSupportVertex(const b2Vec2& d) const
+{
+	int32 bestIndex = 0;
+	float32 bestValue = b2Dot(m_vertices[0], d);
+	for (int32 i = 1; i < m_count; ++i)
+	{
+		float32 value = b2Dot(m_vertices[i], d);
+		if (value > bestValue)
+		{
+			bestIndex = i;
+			bestValue = value;
+		}
+	}
+
+	return m_vertices[bestIndex];
+}
+
+#endif

inc/Box2D/Collision/b2DynamicTree.h

@@ -0,0 +1,289 @@
+/*
+* Copyright (c) 2009 Erin Catto http://www.box2d.org
+*
+* 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_DYNAMIC_TREE_H
+#define B2_DYNAMIC_TREE_H
+
+#include <Box2D/Collision/b2Collision.h>
+#include <Box2D/Common/b2GrowableStack.h>
+
+#define b2_nullNode (-1)
+
+/// A node in the dynamic tree. The client does not interact with this directly.
+struct b2TreeNode
+{
+	bool IsLeaf() const
+	{
+		return child1 == b2_nullNode;
+	}
+
+	/// Enlarged AABB
+	b2AABB aabb;
+
+	void* userData;
+
+	union
+	{
+		int32 parent;
+		int32 next;
+	};
+
+	int32 child1;
+	int32 child2;
+
+	// leaf = 0, free node = -1
+	int32 height;
+};
+
+/// A dynamic AABB tree broad-phase, inspired by Nathanael Presson's btDbvt.
+/// A dynamic tree arranges data in a binary tree to accelerate
+/// queries such as volume queries and ray casts. Leafs are proxies
+/// with an AABB. In the tree we expand the proxy AABB by b2_fatAABBFactor
+/// so that the proxy AABB is bigger than the client object. This allows the client
+/// object to move by small amounts without triggering a tree update.
+///
+/// Nodes are pooled and relocatable, so we use node indices rather than pointers.
+class b2DynamicTree
+{
+public:
+	/// Constructing the tree initializes the node pool.
+	b2DynamicTree();
+
+	/// Destroy the tree, freeing the node pool.
+	~b2DynamicTree();
+
+	/// Create a proxy. Provide a tight fitting AABB and a userData pointer.
+	int32 CreateProxy(const b2AABB& aabb, void* userData);
+
+	/// Destroy a proxy. This asserts if the id is invalid.
+	void DestroyProxy(int32 proxyId);
+
+	/// Move a proxy with a swepted AABB. If the proxy has moved outside of its fattened AABB,
+	/// then the proxy is removed from the tree and re-inserted. Otherwise
+	/// the function returns immediately.
+	/// @return true if the proxy was re-inserted.
+	bool MoveProxy(int32 proxyId, const b2AABB& aabb1, const b2Vec2& displacement);
+
+	/// Get proxy user data.
+	/// @return the proxy user data or 0 if the id is invalid.
+	void* GetUserData(int32 proxyId) const;
+
+	/// Get the fat AABB for a proxy.
+	const b2AABB& GetFatAABB(int32 proxyId) const;
+
+	/// Query an AABB for overlapping proxies. The callback class
+	/// is called for each proxy that overlaps the supplied AABB.
+	template <typename T>
+	void Query(T* callback, const b2AABB& aabb) const;
+
+	/// Ray-cast against the proxies in the tree. This relies on the callback
+	/// to perform a exact ray-cast in the case were the proxy contains a shape.
+	/// The callback also performs the any collision filtering. This has performance
+	/// roughly equal to k * log(n), where k is the number of collisions and n is the
+	/// number of proxies in the tree.
+	/// @param input the ray-cast input data. The ray extends from p1 to p1 + maxFraction * (p2 - p1).
+	/// @param callback a callback class that is called for each proxy that is hit by the ray.
+	template <typename T>
+	void RayCast(T* callback, const b2RayCastInput& input) const;
+
+	/// Validate this tree. For testing.
+	void Validate() const;
+
+	/// Compute the height of the binary tree in O(N) time. Should not be
+	/// called often.
+	int32 GetHeight() const;
+
+	/// Get the maximum balance of an node in the tree. The balance is the difference
+	/// in height of the two children of a node.
+	int32 GetMaxBalance() const;
+
+	/// Get the ratio of the sum of the node areas to the root area.
+	float32 GetAreaRatio() const;
+
+	/// Build an optimal tree. Very expensive. For testing.
+	void RebuildBottomUp();
+
+	/// Shift the world origin. Useful for large worlds.
+	/// The shift formula is: position -= newOrigin
+	/// @param newOrigin the new origin with respect to the old origin
+	void ShiftOrigin(const b2Vec2& newOrigin);
+
+private:
+
+	int32 AllocateNode();
+	void FreeNode(int32 node);
+
+	void InsertLeaf(int32 node);
+	void RemoveLeaf(int32 node);
+
+	int32 Balance(int32 index);
+
+	int32 ComputeHeight() const;
+	int32 ComputeHeight(int32 nodeId) const;
+
+	void ValidateStructure(int32 index) const;
+	void ValidateMetrics(int32 index) const;
+
+	int32 m_root;
+
+	b2TreeNode* m_nodes;
+	int32 m_nodeCount;
+	int32 m_nodeCapacity;
+
+	int32 m_freeList;
+
+	/// This is used to incrementally traverse the tree for re-balancing.
+	uint32 m_path;
+
+	int32 m_insertionCount;
+};
+
+inline void* b2DynamicTree::GetUserData(int32 proxyId) const
+{
+	b2Assert(0 <= proxyId && proxyId < m_nodeCapacity);
+	return m_nodes[proxyId].userData;
+}
+
+inline const b2AABB& b2DynamicTree::GetFatAABB(int32 proxyId) const
+{
+	b2Assert(0 <= proxyId && proxyId < m_nodeCapacity);
+	return m_nodes[proxyId].aabb;
+}
+
+template <typename T>
+inline void b2DynamicTree::Query(T* callback, const b2AABB& aabb) const
+{
+	b2GrowableStack<int32, 256> stack;
+	stack.Push(m_root);
+
+	while (stack.GetCount() > 0)
+	{
+		int32 nodeId = stack.Pop();
+		if (nodeId == b2_nullNode)
+		{
+			continue;
+		}
+
+		const b2TreeNode* node = m_nodes + nodeId;
+
+		if (b2TestOverlap(node->aabb, aabb))
+		{
+			if (node->IsLeaf())
+			{
+				bool proceed = callback->QueryCallback(nodeId);
+				if (proceed == false)
+				{
+					return;
+				}
+			}
+			else
+			{
+				stack.Push(node->child1);
+				stack.Push(node->child2);
+			}
+		}
+	}
+}
+
+template <typename T>
+inline void b2DynamicTree::RayCast(T* callback, const b2RayCastInput& input) const
+{
+	b2Vec2 p1 = input.p1;
+	b2Vec2 p2 = input.p2;
+	b2Vec2 r = p2 - p1;
+	b2Assert(r.LengthSquared() > 0.0f);
+	r.Normalize();
+
+	// v is perpendicular to the segment.
+	b2Vec2 v = b2Cross(1.0f, r);
+	b2Vec2 abs_v = b2Abs(v);
+
+	// Separating axis for segment (Gino, p80).
+	// |dot(v, p1 - c)| > dot(|v|, h)
+
+	float32 maxFraction = input.maxFraction;
+
+	// Build a bounding box for the segment.
+	b2AABB segmentAABB;
+	{
+		b2Vec2 t = p1 + maxFraction * (p2 - p1);
+		segmentAABB.lowerBound = b2Min(p1, t);
+		segmentAABB.upperBound = b2Max(p1, t);
+	}
+
+	b2GrowableStack<int32, 256> stack;
+	stack.Push(m_root);
+
+	while (stack.GetCount() > 0)
+	{
+		int32 nodeId = stack.Pop();
+		if (nodeId == b2_nullNode)
+		{
+			continue;
+		}
+
+		const b2TreeNode* node = m_nodes + nodeId;
+
+		if (b2TestOverlap(node->aabb, segmentAABB) == false)
+		{
+			continue;
+		}
+
+		// Separating axis for segment (Gino, p80).
+		// |dot(v, p1 - c)| > dot(|v|, h)
+		b2Vec2 c = node->aabb.GetCenter();
+		b2Vec2 h = node->aabb.GetExtents();
+		float32 separation = b2Abs(b2Dot(v, p1 - c)) - b2Dot(abs_v, h);
+		if (separation > 0.0f)
+		{
+			continue;
+		}
+
+		if (node->IsLeaf())
+		{
+			b2RayCastInput subInput;
+			subInput.p1 = input.p1;
+			subInput.p2 = input.p2;
+			subInput.maxFraction = maxFraction;
+
+			float32 value = callback->RayCastCallback(subInput, nodeId);
+
+			if (value == 0.0f)
+			{
+				// The client has terminated the ray cast.
+				return;
+			}
+
+			if (value > 0.0f)
+			{
+				// Update segment bounding box.
+				maxFraction = value;
+				b2Vec2 t = p1 + maxFraction * (p2 - p1);
+				segmentAABB.lowerBound = b2Min(p1, t);
+				segmentAABB.upperBound = b2Max(p1, t);
+			}
+		}
+		else
+		{
+			stack.Push(node->child1);
+			stack.Push(node->child2);
+		}
+	}
+}
+
+#endif

inc/Box2D/Collision/b2TimeOfImpact.h

@@ -0,0 +1,58 @@
+/*
+* Copyright (c) 2006-2009 Erin Catto http://www.box2d.org
+*
+* 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_TIME_OF_IMPACT_H
+#define B2_TIME_OF_IMPACT_H
+
+#include <Box2D/Common/b2Math.h>
+#include <Box2D/Collision/b2Distance.h>
+
+/// Input parameters for b2TimeOfImpact
+struct b2TOIInput
+{
+	b2DistanceProxy proxyA;
+	b2DistanceProxy proxyB;
+	b2Sweep sweepA;
+	b2Sweep sweepB;
+	float32 tMax;		// defines sweep interval [0, tMax]
+};
+
+// Output parameters for b2TimeOfImpact.
+struct b2TOIOutput
+{
+	enum State
+	{
+		e_unknown,
+		e_failed,
+		e_overlapped,
+		e_touching,
+		e_separated
+	};
+
+	State state;
+	float32 t;
+};
+
+/// Compute the upper bound on time before two shapes penetrate. Time is represented as
+/// a fraction between [0,tMax]. This uses a swept separating axis and may miss some intermediate,
+/// non-tunneling collision. If you change the time interval, you should call this function
+/// again.
+/// Note: use b2Distance to compute the contact point and normal at the time of impact.
+void b2TimeOfImpact(b2TOIOutput* output, const b2TOIInput* input);
+
+#endif