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diff --git a/thirdparty/bullet/BulletCollision/CollisionDispatch/btBox2dBox2dCollisionAlgorithm.cpp b/thirdparty/bullet/BulletCollision/CollisionDispatch/btBox2dBox2dCollisionAlgorithm.cpp
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+++ b/thirdparty/bullet/BulletCollision/CollisionDispatch/btBox2dBox2dCollisionAlgorithm.cpp
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+/*
+Bullet Continuous Collision Detection and Physics Library
+* The b2CollidePolygons routines are 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.
+*/
+
+///btBox2dBox2dCollisionAlgorithm, with modified b2CollidePolygons routines from the Box2D library.
+///The modifications include: switching from b2Vec to btVector3, redefinition of b2Dot, b2Cross
+
+#include "btBox2dBox2dCollisionAlgorithm.h"
+#include "BulletCollision/CollisionDispatch/btCollisionDispatcher.h"
+#include "BulletCollision/CollisionShapes/btBoxShape.h"
+#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
+#include "BulletCollision/CollisionDispatch/btBoxBoxDetector.h"
+#include "BulletCollision/CollisionShapes/btBox2dShape.h"
+#include "BulletCollision/CollisionDispatch/btCollisionObjectWrapper.h"
+
+#define USE_PERSISTENT_CONTACTS 1
+
+btBox2dBox2dCollisionAlgorithm::btBox2dBox2dCollisionAlgorithm(btPersistentManifold* mf,const btCollisionAlgorithmConstructionInfo& ci,const btCollisionObjectWrapper* obj0Wrap,const btCollisionObjectWrapper* obj1Wrap)
+: btActivatingCollisionAlgorithm(ci,obj0Wrap,obj1Wrap),
+m_ownManifold(false),
+m_manifoldPtr(mf)
+{
+	if (!m_manifoldPtr && m_dispatcher->needsCollision(obj0Wrap->getCollisionObject(),obj1Wrap->getCollisionObject()))
+	{
+		m_manifoldPtr = m_dispatcher->getNewManifold(obj0Wrap->getCollisionObject(),obj1Wrap->getCollisionObject());
+		m_ownManifold = true;
+	}
+}
+
+btBox2dBox2dCollisionAlgorithm::~btBox2dBox2dCollisionAlgorithm()
+{
+	
+	if (m_ownManifold)
+	{
+		if (m_manifoldPtr)
+			m_dispatcher->releaseManifold(m_manifoldPtr);
+	}
+	
+}
+
+
+void b2CollidePolygons(btManifoldResult* manifold,  const btBox2dShape* polyA, const btTransform& xfA, const btBox2dShape* polyB, const btTransform& xfB);
+
+//#include <stdio.h>
+void btBox2dBox2dCollisionAlgorithm::processCollision (const btCollisionObjectWrapper* body0Wrap,const btCollisionObjectWrapper* body1Wrap,const btDispatcherInfo& dispatchInfo,btManifoldResult* resultOut)
+{
+	if (!m_manifoldPtr)
+		return;
+
+	
+	const btBox2dShape* box0 = (const btBox2dShape*)body0Wrap->getCollisionShape();
+	const btBox2dShape* box1 = (const btBox2dShape*)body1Wrap->getCollisionShape();
+
+	resultOut->setPersistentManifold(m_manifoldPtr);
+
+	b2CollidePolygons(resultOut,box0,body0Wrap->getWorldTransform(),box1,body1Wrap->getWorldTransform());
+
+	//  refreshContactPoints is only necessary when using persistent contact points. otherwise all points are newly added
+	if (m_ownManifold)
+	{
+		resultOut->refreshContactPoints();
+	}
+
+}
+
+btScalar btBox2dBox2dCollisionAlgorithm::calculateTimeOfImpact(btCollisionObject* /*body0*/,btCollisionObject* /*body1*/,const btDispatcherInfo& /*dispatchInfo*/,btManifoldResult* /*resultOut*/)
+{
+	//not yet
+	return 1.f;
+}
+
+
+struct ClipVertex
+{
+	btVector3 v;
+	int id;
+	//b2ContactID id;
+	//b2ContactID id;
+};
+
+#define b2Dot(a,b) (a).dot(b)
+#define b2Mul(a,b) (a)*(b)
+#define b2MulT(a,b) (a).transpose()*(b)
+#define b2Cross(a,b) (a).cross(b)
+#define btCrossS(a,s) btVector3(s * a.getY(), -s * a.getX(),0.f)
+
+int b2_maxManifoldPoints =2;
+
+static int ClipSegmentToLine(ClipVertex vOut[2], ClipVertex vIn[2],
+					  const btVector3& normal, btScalar offset)
+{
+	// Start with no output points
+	int numOut = 0;
+
+	// Calculate the distance of end points to the line
+	btScalar distance0 = b2Dot(normal, vIn[0].v) - offset;
+	btScalar distance1 = b2Dot(normal, vIn[1].v) - offset;
+
+	// If the points are behind the plane
+	if (distance0 <= 0.0f) vOut[numOut++] = vIn[0];
+	if (distance1 <= 0.0f) vOut[numOut++] = vIn[1];
+
+	// If the points are on different sides of the plane
+	if (distance0 * distance1 < 0.0f)
+	{
+		// Find intersection point of edge and plane
+		btScalar interp = distance0 / (distance0 - distance1);
+		vOut[numOut].v = vIn[0].v + interp * (vIn[1].v - vIn[0].v);
+		if (distance0 > 0.0f)
+		{
+			vOut[numOut].id = vIn[0].id;
+		}
+		else
+		{
+			vOut[numOut].id = vIn[1].id;
+		}
+		++numOut;
+	}
+
+	return numOut;
+}
+
+// Find the separation between poly1 and poly2 for a give edge normal on poly1.
+static btScalar EdgeSeparation(const btBox2dShape* poly1, const btTransform& xf1, int edge1,
+							  const btBox2dShape* poly2, const btTransform& xf2)
+{
+	const btVector3* vertices1 = poly1->getVertices();
+	const btVector3* normals1 = poly1->getNormals();
+
+	int count2 = poly2->getVertexCount();
+	const btVector3* vertices2 = poly2->getVertices();
+
+	btAssert(0 <= edge1 && edge1 < poly1->getVertexCount());
+
+	// Convert normal from poly1's frame into poly2's frame.
+	btVector3 normal1World = b2Mul(xf1.getBasis(), normals1[edge1]);
+	btVector3 normal1 = b2MulT(xf2.getBasis(), normal1World);
+
+	// Find support vertex on poly2 for -normal.
+	int index = 0;
+	btScalar minDot = BT_LARGE_FLOAT;
+
+    if( count2 > 0 )
+        index = (int) normal1.minDot( vertices2, count2, minDot);
+
+	btVector3 v1 = b2Mul(xf1, vertices1[edge1]);
+	btVector3 v2 = b2Mul(xf2, vertices2[index]);
+	btScalar separation = b2Dot(v2 - v1, normal1World);
+	return separation;
+}
+
+// Find the max separation between poly1 and poly2 using edge normals from poly1.
+static btScalar FindMaxSeparation(int* edgeIndex,
+								 const btBox2dShape* poly1, const btTransform& xf1,
+								 const btBox2dShape* poly2, const btTransform& xf2)
+{
+	int count1 = poly1->getVertexCount();
+	const btVector3* normals1 = poly1->getNormals();
+
+	// Vector pointing from the centroid of poly1 to the centroid of poly2.
+	btVector3 d = b2Mul(xf2, poly2->getCentroid()) - b2Mul(xf1, poly1->getCentroid());
+	btVector3 dLocal1 = b2MulT(xf1.getBasis(), d);
+
+	// Find edge normal on poly1 that has the largest projection onto d.
+	int edge = 0;
+    btScalar maxDot;
+    if( count1 > 0 )
+        edge = (int) dLocal1.maxDot( normals1, count1, maxDot);
+
+	// Get the separation for the edge normal.
+	btScalar s = EdgeSeparation(poly1, xf1, edge, poly2, xf2);
+	if (s > 0.0f)
+	{
+		return s;
+	}
+
+	// Check the separation for the previous edge normal.
+	int prevEdge = edge - 1 >= 0 ? edge - 1 : count1 - 1;
+	btScalar sPrev = EdgeSeparation(poly1, xf1, prevEdge, poly2, xf2);
+	if (sPrev > 0.0f)
+	{
+		return sPrev;
+	}
+
+	// Check the separation for the next edge normal.
+	int nextEdge = edge + 1 < count1 ? edge + 1 : 0;
+	btScalar sNext = EdgeSeparation(poly1, xf1, nextEdge, poly2, xf2);
+	if (sNext > 0.0f)
+	{
+		return sNext;
+	}
+
+	// Find the best edge and the search direction.
+	int bestEdge;
+	btScalar bestSeparation;
+	int increment;
+	if (sPrev > s && sPrev > sNext)
+	{
+		increment = -1;
+		bestEdge = prevEdge;
+		bestSeparation = sPrev;
+	}
+	else if (sNext > s)
+	{
+		increment = 1;
+		bestEdge = nextEdge;
+		bestSeparation = sNext;
+	}
+	else
+	{
+		*edgeIndex = edge;
+		return s;
+	}
+
+	// Perform a local search for the best edge normal.
+	for ( ; ; )
+	{
+		if (increment == -1)
+			edge = bestEdge - 1 >= 0 ? bestEdge - 1 : count1 - 1;
+		else
+			edge = bestEdge + 1 < count1 ? bestEdge + 1 : 0;
+
+		s = EdgeSeparation(poly1, xf1, edge, poly2, xf2);
+		if (s > 0.0f)
+		{
+			return s;
+		}
+
+		if (s > bestSeparation)
+		{
+			bestEdge = edge;
+			bestSeparation = s;
+		}
+		else
+		{
+			break;
+		}
+	}
+
+	*edgeIndex = bestEdge;
+	return bestSeparation;
+}
+
+static void FindIncidentEdge(ClipVertex c[2],
+							 const btBox2dShape* poly1, const btTransform& xf1, int edge1,
+							 const btBox2dShape* poly2, const btTransform& xf2)
+{
+	const btVector3* normals1 = poly1->getNormals();
+
+	int count2 = poly2->getVertexCount();
+	const btVector3* vertices2 = poly2->getVertices();
+	const btVector3* normals2 = poly2->getNormals();
+
+	btAssert(0 <= edge1 && edge1 < poly1->getVertexCount());
+
+	// Get the normal of the reference edge in poly2's frame.
+	btVector3 normal1 = b2MulT(xf2.getBasis(), b2Mul(xf1.getBasis(), normals1[edge1]));
+
+	// Find the incident edge on poly2.
+	int index = 0;
+	btScalar minDot = BT_LARGE_FLOAT;
+	for (int i = 0; i < count2; ++i)
+	{
+		btScalar dot = b2Dot(normal1, normals2[i]);
+		if (dot < minDot)
+		{
+			minDot = dot;
+			index = i;
+		}
+	}
+
+	// Build the clip vertices for the incident edge.
+	int i1 = index;
+	int i2 = i1 + 1 < count2 ? i1 + 1 : 0;
+
+	c[0].v = b2Mul(xf2, vertices2[i1]);
+//	c[0].id.features.referenceEdge = (unsigned char)edge1;
+//	c[0].id.features.incidentEdge = (unsigned char)i1;
+//	c[0].id.features.incidentVertex = 0;
+
+	c[1].v = b2Mul(xf2, vertices2[i2]);
+//	c[1].id.features.referenceEdge = (unsigned char)edge1;
+//	c[1].id.features.incidentEdge = (unsigned char)i2;
+//	c[1].id.features.incidentVertex = 1;
+}
+
+// Find edge normal of max separation on A - return if separating axis is found
+// Find edge normal of max separation on B - return if separation axis is found
+// Choose reference edge as min(minA, minB)
+// Find incident edge
+// Clip
+
+// The normal points from 1 to 2
+void b2CollidePolygons(btManifoldResult* manifold,
+					  const btBox2dShape* polyA, const btTransform& xfA,
+					  const btBox2dShape* polyB, const btTransform& xfB)
+{
+
+	int edgeA = 0;
+	btScalar separationA = FindMaxSeparation(&edgeA, polyA, xfA, polyB, xfB);
+	if (separationA > 0.0f)
+		return;
+
+	int edgeB = 0;
+	btScalar separationB = FindMaxSeparation(&edgeB, polyB, xfB, polyA, xfA);
+	if (separationB > 0.0f)
+		return;
+
+	const btBox2dShape* poly1;	// reference poly
+	const btBox2dShape* poly2;	// incident poly
+	btTransform xf1, xf2;
+	int edge1;		// reference edge
+	unsigned char flip;
+	const btScalar k_relativeTol = 0.98f;
+	const btScalar k_absoluteTol = 0.001f;
+
+	// TODO_ERIN use "radius" of poly for absolute tolerance.
+	if (separationB > k_relativeTol * separationA + k_absoluteTol)
+	{
+		poly1 = polyB;
+		poly2 = polyA;
+		xf1 = xfB;
+		xf2 = xfA;
+		edge1 = edgeB;
+		flip = 1;
+	}
+	else
+	{
+		poly1 = polyA;
+		poly2 = polyB;
+		xf1 = xfA;
+		xf2 = xfB;
+		edge1 = edgeA;
+		flip = 0;
+	}
+
+	ClipVertex incidentEdge[2];
+	FindIncidentEdge(incidentEdge, poly1, xf1, edge1, poly2, xf2);
+
+	int count1 = poly1->getVertexCount();
+	const btVector3* vertices1 = poly1->getVertices();
+
+	btVector3 v11 = vertices1[edge1];
+	btVector3 v12 = edge1 + 1 < count1 ? vertices1[edge1+1] : vertices1[0];
+
+	//btVector3 dv = v12 - v11;
+	btVector3 sideNormal = b2Mul(xf1.getBasis(), v12 - v11);
+	sideNormal.normalize();
+	btVector3 frontNormal = btCrossS(sideNormal, 1.0f);
+	
+	
+	v11 = b2Mul(xf1, v11);
+	v12 = b2Mul(xf1, v12);
+
+	btScalar frontOffset = b2Dot(frontNormal, v11);
+	btScalar sideOffset1 = -b2Dot(sideNormal, v11);
+	btScalar sideOffset2 = b2Dot(sideNormal, v12);
+
+	// Clip incident edge against extruded edge1 side edges.
+	ClipVertex clipPoints1[2];
+	clipPoints1[0].v.setValue(0,0,0);
+	clipPoints1[1].v.setValue(0,0,0);
+
+	ClipVertex clipPoints2[2];
+	clipPoints2[0].v.setValue(0,0,0);
+	clipPoints2[1].v.setValue(0,0,0);
+
+
+	int np;
+
+	// Clip to box side 1
+	np = ClipSegmentToLine(clipPoints1, incidentEdge, -sideNormal, sideOffset1);
+
+	if (np < 2)
+		return;
+
+	// Clip to negative box side 1
+	np = ClipSegmentToLine(clipPoints2, clipPoints1,  sideNormal, sideOffset2);
+
+	if (np < 2)
+	{
+		return;
+	}
+
+	// Now clipPoints2 contains the clipped points.
+	btVector3 manifoldNormal = flip ? -frontNormal : frontNormal;
+
+	int pointCount = 0;
+	for (int i = 0; i < b2_maxManifoldPoints; ++i)
+	{
+		btScalar separation = b2Dot(frontNormal, clipPoints2[i].v) - frontOffset;
+
+		if (separation <= 0.0f)
+		{
+			
+			//b2ManifoldPoint* cp = manifold->points + pointCount;
+			//btScalar separation = separation;
+			//cp->localPoint1 = b2MulT(xfA, clipPoints2[i].v);
+			//cp->localPoint2 = b2MulT(xfB, clipPoints2[i].v);
+
+			manifold->addContactPoint(-manifoldNormal,clipPoints2[i].v,separation);
+
+//			cp->id = clipPoints2[i].id;
+//			cp->id.features.flip = flip;
+			++pointCount;
+		}
+	}
+
+//	manifold->pointCount = pointCount;}
+}