1 /*
2 Bullet Continuous Collision Detection and Physics Library
3 Copyright (c) 2003-2006 Erwin Coumans  https://bulletphysics.org
4 
5 This software is provided 'as-is', without any express or implied warranty.
6 In no event will the authors be held liable for any damages arising from the use of this software.
7 Permission is granted to anyone to use this software for any purpose,
8 including commercial applications, and to alter it and redistribute it freely,
9 subject to the following restrictions:
10 
11 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.
12 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
13 3. This notice may not be removed or altered from any source distribution.
14 */
15 
16 #ifndef BT_HASHED_SIMPLE_PAIR_CACHE_H
17 #define BT_HASHED_SIMPLE_PAIR_CACHE_H
18 
19 #include "LinearMath/btAlignedObjectArray.h"
20 
21 const int BT_SIMPLE_NULL_PAIR = 0xffffffff;
22 
23 struct btSimplePair
24 {
btSimplePairbtSimplePair25 	btSimplePair(int indexA, int indexB)
26 		: m_indexA(indexA),
27 		  m_indexB(indexB),
28 		  m_userPointer(0)
29 	{
30 	}
31 
32 	int m_indexA;
33 	int m_indexB;
34 	union {
35 		void* m_userPointer;
36 		int m_userValue;
37 	};
38 };
39 
40 typedef btAlignedObjectArray<btSimplePair> btSimplePairArray;
41 
42 #ifdef BT_DEBUG_COLLISION_PAIRS
43 extern int gOverlappingSimplePairs;
44 extern int gRemoveSimplePairs;
45 extern int gAddedSimplePairs;
46 extern int gFindSimplePairs;
47 #endif  //BT_DEBUG_COLLISION_PAIRS
48 
49 class btHashedSimplePairCache
50 {
51 	btSimplePairArray m_overlappingPairArray;
52 
53 protected:
54 	btAlignedObjectArray<int> m_hashTable;
55 	btAlignedObjectArray<int> m_next;
56 
57 public:
58 	btHashedSimplePairCache();
59 	virtual ~btHashedSimplePairCache();
60 
61 	void removeAllPairs();
62 
63 	virtual void* removeOverlappingPair(int indexA, int indexB);
64 
65 	// Add a pair and return the new pair. If the pair already exists,
66 	// no new pair is created and the old one is returned.
addOverlappingPair(int indexA,int indexB)67 	virtual btSimplePair* addOverlappingPair(int indexA, int indexB)
68 	{
69 #ifdef BT_DEBUG_COLLISION_PAIRS
70 		gAddedSimplePairs++;
71 #endif
72 
73 		return internalAddPair(indexA, indexB);
74 	}
75 
getOverlappingPairArrayPtr()76 	virtual btSimplePair* getOverlappingPairArrayPtr()
77 	{
78 		return &m_overlappingPairArray[0];
79 	}
80 
getOverlappingPairArrayPtr()81 	const btSimplePair* getOverlappingPairArrayPtr() const
82 	{
83 		return &m_overlappingPairArray[0];
84 	}
85 
getOverlappingPairArray()86 	btSimplePairArray& getOverlappingPairArray()
87 	{
88 		return m_overlappingPairArray;
89 	}
90 
getOverlappingPairArray()91 	const btSimplePairArray& getOverlappingPairArray() const
92 	{
93 		return m_overlappingPairArray;
94 	}
95 
96 	btSimplePair* findPair(int indexA, int indexB);
97 
GetCount()98 	int GetCount() const { return m_overlappingPairArray.size(); }
99 
getNumOverlappingPairs()100 	int getNumOverlappingPairs() const
101 	{
102 		return m_overlappingPairArray.size();
103 	}
104 
105 private:
106 	btSimplePair* internalAddPair(int indexA, int indexB);
107 
108 	void growTables();
109 
equalsPair(const btSimplePair & pair,int indexA,int indexB)110 	SIMD_FORCE_INLINE bool equalsPair(const btSimplePair& pair, int indexA, int indexB)
111 	{
112 		return pair.m_indexA == indexA && pair.m_indexB == indexB;
113 	}
114 
getHash(unsigned int indexA,unsigned int indexB)115 	SIMD_FORCE_INLINE unsigned int getHash(unsigned int indexA, unsigned int indexB)
116 	{
117 		unsigned int key = indexA | (indexB << 16);
118 		// Thomas Wang's hash
119 
120 		key += ~(key << 15);
121 		key ^= (key >> 10);
122 		key += (key << 3);
123 		key ^= (key >> 6);
124 		key += ~(key << 11);
125 		key ^= (key >> 16);
126 		return key;
127 	}
128 
internalFindPair(int proxyIdA,int proxyIdB,int hash)129 	SIMD_FORCE_INLINE btSimplePair* internalFindPair(int proxyIdA, int proxyIdB, int hash)
130 	{
131 		int index = m_hashTable[hash];
132 
133 		while (index != BT_SIMPLE_NULL_PAIR && equalsPair(m_overlappingPairArray[index], proxyIdA, proxyIdB) == false)
134 		{
135 			index = m_next[index];
136 		}
137 
138 		if (index == BT_SIMPLE_NULL_PAIR)
139 		{
140 			return NULL;
141 		}
142 
143 		btAssert(index < m_overlappingPairArray.size());
144 
145 		return &m_overlappingPairArray[index];
146 	}
147 };
148 
149 #endif  //BT_HASHED_SIMPLE_PAIR_CACHE_H
150