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diff --git a/extern/bullet2/BulletCollision/CollisionDispatch/btUnionFind.cpp b/extern/bullet2/BulletCollision/CollisionDispatch/btUnionFind.cpp
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+++ b/extern/bullet2/BulletCollision/CollisionDispatch/btUnionFind.cpp
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+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2003-2006 Erwin Coumans  http://continuousphysics.com/Bullet/
+
+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.
+*/
+
+#include "btUnionFind.h"
+
+
+
+btUnionFind::~btUnionFind()
+{
+	Free();
+
+}
+
+btUnionFind::btUnionFind()
+{ 
+
+}
+
+void	btUnionFind::allocate(int N)
+{
+	m_elements.resize(N);
+}
+void	btUnionFind::Free()
+{
+	m_elements.clear();
+}
+
+
+void	btUnionFind::reset(int N)
+{
+	allocate(N);
+
+	for (int i = 0; i < N; i++) 
+	{ 
+		m_elements[i].m_id = i; m_elements[i].m_sz = 1; 
+	} 
+}
+
+
+class btUnionFindElementSortPredicate
+{
+	public:
+
+		bool operator() ( const btElement& lhs, const btElement& rhs )
+		{
+			return lhs.m_id < rhs.m_id;
+		}
+};
+
+///this is a special operation, destroying the content of btUnionFind.
+///it sorts the elements, based on island id, in order to make it easy to iterate over islands
+void	btUnionFind::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(), btUnionFindElementSortPredicate);
+	  m_elements.quickSort(btUnionFindElementSortPredicate());
+
+}
+