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[blok] / Box2D / Source / Collision / b2PairManager.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.
+*/
+
+// The pair manager is used by the broad-phase to quickly add/remove/find pairs
+// of overlapping proxies. It is based closely on code provided by Pierre Terdiman.
+// http://www.codercorner.com/IncrementalSAP.txt
+
+#ifndef B2_PAIR_MANAGER_H
+#define B2_PAIR_MANAGER_H
+
+#include "../Common/b2Settings.h"
+#include "../Common/b2Math.h"
+
+#include <climits>
+
+class b2BroadPhase;
+struct b2Proxy;
+
+const uint16 b2_nullPair = USHRT_MAX;
+const uint16 b2_nullProxy = USHRT_MAX;
+const int32 b2_tableCapacity = b2_maxPairs;    // must be a power of two
+const int32 b2_tableMask = b2_tableCapacity - 1;
+
+struct b2Pair
+{
+       enum
+       {
+               e_pairBuffered  = 0x0001,
+               e_pairRemoved   = 0x0002,
+               e_pairFinal             = 0x0004,
+       };
+
+       void SetBuffered()              { status |= e_pairBuffered; }
+       void ClearBuffered()    { status &= ~e_pairBuffered; }
+       bool IsBuffered()               { return (status & e_pairBuffered) == e_pairBuffered; }
+
+       void SetRemoved()               { status |= e_pairRemoved; }
+       void ClearRemoved()             { status &= ~e_pairRemoved; }
+       bool IsRemoved()                { return (status & e_pairRemoved) == e_pairRemoved; }
+
+       void SetFinal()         { status |= e_pairFinal; }
+       bool IsFinal()          { return (status & e_pairFinal) == e_pairFinal; }
+
+       void* userData;
+       uint16 proxyId1;
+       uint16 proxyId2;
+       uint16 next;
+       uint16 status;
+};
+
+struct b2BufferedPair
+{
+       uint16 proxyId1;
+       uint16 proxyId2;
+};
+
+class b2PairCallback
+{
+public:
+       virtual ~b2PairCallback() {}
+
+       // This should return the new pair user data. It is ok if the
+       // user data is null.
+       virtual void* PairAdded(void* proxyUserData1, void* proxyUserData2) = 0;
+
+       // This should free the pair's user data. In extreme circumstances, it is possible
+       // this will be called with null pairUserData because the pair never existed.
+       virtual void PairRemoved(void* proxyUserData1, void* proxyUserData2, void* pairUserData) = 0;
+};
+
+class b2PairManager
+{
+public:
+       b2PairManager();
+
+       void Initialize(b2BroadPhase* broadPhase, b2PairCallback* callback);
+
+       void AddBufferedPair(int32 proxyId1, int32 proxyId2);
+       void RemoveBufferedPair(int32 proxyId1, int32 proxyId2);
+
+       void Commit();
+
+private:
+       b2Pair* Find(int32 proxyId1, int32 proxyId2);
+       b2Pair* Find(int32 proxyId1, int32 proxyId2, uint32 hashValue);
+
+       b2Pair* AddPair(int32 proxyId1, int32 proxyId2);
+       void* RemovePair(int32 proxyId1, int32 proxyId2);
+
+       void ValidateBuffer();
+       void ValidateTable();
+
+public:
+       b2BroadPhase *m_broadPhase;
+       b2PairCallback *m_callback;
+       b2Pair m_pairs[b2_maxPairs];
+       uint16 m_freePair;
+       int32 m_pairCount;
+
+       b2BufferedPair m_pairBuffer[b2_maxPairs];
+       int32 m_pairBufferCount;
+
+       uint16 m_hashTable[b2_tableCapacity];
+};
+
+#endif