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optimized the island management. It was unoptimized, and becomes a bottleneck for large amounts of objects.

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This commit is contained in:
ejcoumans
2006-09-14 23:43:50 +00:00
parent db2265ce03
commit 0607bfe9de
3 changed files with 236 additions and 132 deletions
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77
Bullet/CollisionDispatch/UnionFind.cpp
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@@ -15,28 +15,9 @@ subject to the following restrictions:
#include "UnionFind.h"
#include <assert.h>
#include <algorithm>
int UnionFind::find(int x)
{
assert(x < m_N);
assert(x >= 0);
while (x != m_id[x])
{
//not really a reason not to use path compression, and it flattens the trees/improves find performance dramatically
#define USE_PATH_COMPRESSION 1
#ifdef USE_PATH_COMPRESSION
//
m_id[x] = m_id[m_id[x]];
#endif //
x = m_id[x];
assert(x < m_N);
assert(x >= 0);
}
return x;
}
UnionFind::~UnionFind()
{
@@ -45,8 +26,7 @@ UnionFind::~UnionFind()
}
UnionFind::UnionFind()
:m_id(0),
m_sz(0),
:m_elements(0),
m_N(0)
{
@@ -56,11 +36,10 @@ void UnionFind::Allocate(int N)
{
if (m_N < N)
{
Free();
//Free(); //not necessary with stl vectors
m_N = N;
m_id = new int[N];
m_sz = new int[N];
m_elements.resize(N);// = new Element[N];
}
}
void UnionFind::Free()
@@ -68,8 +47,7 @@ void UnionFind::Free()
if (m_N)
{
m_N=0;
delete m_id;
delete m_sz;
m_elements.clear();
}
}
@@ -80,29 +58,32 @@ void UnionFind::reset(int N)
for (int i = 0; i < m_N; i++)
{
m_id[i] = i; m_sz[i] = 1;
m_elements[i].m_id = i; m_elements[i].m_sz = 1;
}
}
int UnionFind ::find(int p, int q)
{
return (find(p) == find(q));
}
void UnionFind ::unite(int p, int q)
bool UnionFindElementSortPredicate(const Element& lhs, const Element& rhs)
{
int i = find(p), j = find(q);
if (i == j)
return;
//weighted quick union, this keeps the 'trees' balanced, and keeps performance of unite O( log(n) )
if (m_sz[i] < m_sz[j])
{
m_id[i] = j; m_sz[j] += m_sz[i];
}
else
{
m_id[j] = i; m_sz[i] += m_sz[j];
}
return lhs.m_id < rhs.m_id;
}
///this is a special operation, destroying the content of UnionFind.
///it sorts the elements, based on island id, in order to make it easy to iterate over islands
void UnionFind::sortIslands()
{
//first store the original body index, and islandId
int numElements = m_elements.size();
for (int i=0;i<numElements;i++)
{
m_elements[i].m_id = find(i);
m_elements[i].m_sz = i;
}
// Sort the vector using predicate and std::sort
std::sort(m_elements.begin(), m_elements.end(), UnionFindElementSortPredicate);
}