initial commit. includes PhsyicsBox2dExtension

AndEngine/jni/Box2D/Collision/b2DynamicTree.h

@@ -0,0 +1,286 @@
+/*
+* Copyright (c) 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_DYNAMIC_TREE_H
+#define B2_DYNAMIC_TREE_H
+
+#include "Box2D/Collision/b2Collision.h"
+
+/// A dynamic AABB tree broad-phase, inspired by Nathanael Presson's btDbvt.
+
+#define b2_nullNode (-1)
+
+/// A node in the dynamic tree. The client does not interact with this directly.
+struct b2DynamicTreeNode
+{
+	bool IsLeaf() const
+	{
+		return child1 == b2_nullNode;
+	}
+
+	/// This is the fattened AABB.
+	b2AABB aabb;
+
+	//int32 userData;
+	void* userData;
+
+	union
+	{
+		int32 parent;
+		int32 next;
+	};
+
+	int32 child1;
+	int32 child2;
+};
+
+/// 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);
+
+	/// Perform some iterations to re-balance the tree.
+	void Rebalance(int32 iterations);
+
+	/// 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;
+
+	/// Compute the height of the tree.
+	int32 ComputeHeight() 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;
+
+private:
+
+	int32 AllocateNode();
+	void FreeNode(int32 node);
+
+	void InsertLeaf(int32 node);
+	void RemoveLeaf(int32 node);
+
+	int32 ComputeHeight(int32 nodeId) const;
+
+	int32 m_root;
+
+	b2DynamicTreeNode* m_nodes;
+	int32 m_nodeCount;
+	int32 m_nodeCapacity;
+
+	int32 m_freeList;
+
+	/// This is used 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
+{
+	const int32 k_stackSize = 128;
+	int32 stack[k_stackSize];
+
+	int32 count = 0;
+	stack[count++] = m_root;
+
+	while (count > 0)
+	{
+		int32 nodeId = stack[--count];
+		if (nodeId == b2_nullNode)
+		{
+			continue;
+		}
+
+		const b2DynamicTreeNode* node = m_nodes + nodeId;
+
+		if (b2TestOverlap(node->aabb, aabb))
+		{
+			if (node->IsLeaf())
+			{
+				bool proceed = callback->QueryCallback(nodeId);
+				if (proceed == false)
+				{
+					return;
+				}
+			}
+			else
+			{
+				if (count < k_stackSize)
+				{
+					stack[count++] = node->child1;
+				}
+
+				if (count < k_stackSize)
+				{
+					stack[count++] = 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);
+	}
+
+	const int32 k_stackSize = 128;
+	int32 stack[k_stackSize];
+
+	int32 count = 0;
+	stack[count++] = m_root;
+
+	while (count > 0)
+	{
+		int32 nodeId = stack[--count];
+		if (nodeId == b2_nullNode)
+		{
+			continue;
+		}
+
+		const b2DynamicTreeNode* 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
+		{
+			if (count < k_stackSize)
+			{
+				stack[count++] = node->child1;
+			}
+
+			if (count < k_stackSize)
+			{
+				stack[count++] = node->child2;
+			}
+		}
+	}
+}
+
+#endif