Applied polar decomposition patch. Fixes Issue 621. Thanks to Christian for the report, Joshua for the fix, Dongsoo for checking the fix.

Applied picking cloth patch. Fixes Issue 646. Thanks to Dongsoo.
Applied patch Softbody updateConstraints. Fixes Issue 503. Thanks to Dave Bruce Phillips and Dongsoo.
Fix various warnigns under Mac OSX.

src/BulletSoftBody/btSoftBody.cpp

@@ -110,7 +110,7 @@ void	btSoftBody::initDefaults()
 	m_initialWorldTransform.setIdentity();
 
 	m_windVelocity = btVector3(0,0,0);
-
+	m_restLengthScale = btScalar(1.0);
 }
 
 //
@@ -505,6 +505,18 @@ void			btSoftBody::addAeroForceToNode(const btVector3& windVelocity,int nodeInde
 					if ( 0 < n_dot_v && n_dot_v < 0.98480f)
 						fLift = 0.5f * kLF * medium.m_density * rel_v_len * tri_area * btSqrt(1.0f-n_dot_v*n_dot_v) * (nrm.cross(rel_v_nrm).cross(rel_v_nrm));
 
+					// Check if the velocity change resulted by aero drag force exceeds the current velocity of the node.
+					btVector3 del_v_by_fDrag = fDrag*n.m_im*m_sst.sdt;										
+					btScalar del_v_by_fDrag_len2 = del_v_by_fDrag.length2();
+					btScalar v_len2 = n.m_v.length2();
+
+					if (del_v_by_fDrag_len2 >= v_len2 && del_v_by_fDrag_len2 > 0)
+					{
+						btScalar del_v_by_fDrag_len = del_v_by_fDrag.length();
+						btScalar v_len = n.m_v.length();
+						fDrag *= 0.8*(v_len / del_v_by_fDrag_len);
+					}
+
 					n.m_f += fDrag;
 					n.m_f += fLift;
 				}
@@ -535,8 +547,8 @@ void			btSoftBody::addAeroForceToFace(const btVector3& windVelocity,int faceInde
 	const btScalar dt = m_sst.sdt;
 	const btScalar kLF = m_cfg.kLF;
 	const btScalar kDG = m_cfg.kDG;
-	const btScalar kPR = m_cfg.kPR;
-	const btScalar kVC = m_cfg.kVC;
+//	const btScalar kPR = m_cfg.kPR;
+//	const btScalar kVC = m_cfg.kVC;
 	const bool as_lift = kLF>0;
 	const bool as_drag = kDG>0;
 	const bool as_aero = as_lift || as_drag;
@@ -586,6 +598,18 @@ void			btSoftBody::addAeroForceToFace(const btVector3& windVelocity,int faceInde
 				{
 					if (f.m_n[j]->m_im>0)
 					{
+						// Check if the velocity change resulted by aero drag force exceeds the current velocity of the node.
+						btVector3 del_v_by_fDrag = fDrag*f.m_n[j]->m_im*m_sst.sdt;										
+						btScalar del_v_by_fDrag_len2 = del_v_by_fDrag.length2();
+						btScalar v_len2 = f.m_n[j]->m_v.length2();
+
+						if (del_v_by_fDrag_len2 >= v_len2 && del_v_by_fDrag_len2 > 0)
+						{
+							btScalar del_v_by_fDrag_len = del_v_by_fDrag.length();
+							btScalar v_len = f.m_n[j]->m_v.length();
+							fDrag *= 0.8*(v_len / del_v_by_fDrag_len);
+						}
+
 						f.m_n[j]->m_f += fDrag; 
 						f.m_n[j]->m_f += fLift;
 					}
@@ -816,6 +840,27 @@ void			btSoftBody::scale(const btVector3& scl)
 	updateConstants();
 }
 
+//
+btScalar btSoftBody::getRestLengthScale()
+{
+	return m_restLengthScale;
+}
+
+//
+void btSoftBody::setRestLengthScale(btScalar restLengthScale)
+{
+	for(int i=0, ni=m_links.size(); i<ni; ++i)
+	{
+		Link&		l=m_links[i];
+		l.m_rl	=	l.m_rl / m_restLengthScale * restLengthScale;
+		l.m_c1	=	l.m_rl*l.m_rl;
+	}
+	m_restLengthScale = restLengthScale;
+	
+	if (getActivationState() == ISLAND_SLEEPING);
+	activate();
+}
+
 //
 void			btSoftBody::setPose(bool bvolume,bool bframe)
 {
@@ -863,9 +908,20 @@ void			btSoftBody::setPose(bool bvolume,bool bframe)
 		m_pose.m_aqq[2]+=mq.z()*q;
 	}
 	m_pose.m_aqq=m_pose.m_aqq.inverse();
+	
 	updateConstants();
 }
 
+void				btSoftBody::resetLinkRestLengths()
+{
+	for(int i=0, ni=m_links.size();i<ni;++i)
+	{
+		Link& l =	m_links[i];
+		l.m_rl	=	(l.m_n[0]->m_x-l.m_n[1]->m_x).length();
+		l.m_c1	=	l.m_rl*l.m_rl;
+	}
+}
+
 //
 btScalar		btSoftBody::getVolume() const
 {
@@ -1587,7 +1643,7 @@ bool			btSoftBody::cutLink(int node0,int node1,btScalar position)
 {
 	bool			done=false;
 	int i,ni;
-	const btVector3	d=m_nodes[node0].m_x-m_nodes[node1].m_x;
+//	const btVector3	d=m_nodes[node0].m_x-m_nodes[node1].m_x;
 	const btVector3	x=Lerp(m_nodes[node0].m_x,m_nodes[node1].m_x,position);
 	const btVector3	v=Lerp(m_nodes[node0].m_v,m_nodes[node1].m_v,position);
 	const btScalar	m=1;
@@ -2178,7 +2234,7 @@ bool				btSoftBody::checkContact(	const btCollisionObjectWrapper* colObjWrap,
 {
 	btVector3 nrm;
 	const btCollisionShape *shp = colObjWrap->getCollisionShape();
-	const btRigidBody *tmpRigid = btRigidBody::upcast(colObjWrap->getCollisionObject());
+//	const btRigidBody *tmpRigid = btRigidBody::upcast(colObjWrap->getCollisionObject());
 	//const btTransform &wtr = tmpRigid ? tmpRigid->getWorldTransform() : colObjWrap->getWorldTransform();
 	const btTransform &wtr = colObjWrap->getWorldTransform();
 	//todo: check which transform is needed here
@@ -2307,51 +2363,93 @@ void					btSoftBody::updatePose()
 }
 
 //
-void				btSoftBody::updateConstants()
+void				btSoftBody::updateArea(bool averageArea)
 {
 	int i,ni;
 
+	/* Face area		*/ 
+	for(i=0,ni=m_faces.size();i<ni;++i)
+	{
+		Face&		f=m_faces[i];
+		f.m_ra	=	AreaOf(f.m_n[0]->m_x,f.m_n[1]->m_x,f.m_n[2]->m_x);
+	}
+	
+	/* Node area		*/ 
+
+	if (averageArea)
+	{
+		btAlignedObjectArray<int>	counts;
+		counts.resize(m_nodes.size(),0);
+		for(i=0,ni=m_nodes.size();i<ni;++i)
+		{
+			m_nodes[i].m_area	=	0;
+		}
+		for(i=0,ni=m_faces.size();i<ni;++i)
+		{
+			btSoftBody::Face&	f=m_faces[i];
+			for(int j=0;j<3;++j)
+			{
+				const int index=(int)(f.m_n[j]-&m_nodes[0]);
+				counts[index]++;
+				f.m_n[j]->m_area+=btFabs(f.m_ra);
+			}
+		}
+		for(i=0,ni=m_nodes.size();i<ni;++i)
+		{
+			if(counts[i]>0)
+				m_nodes[i].m_area/=(btScalar)counts[i];
+			else
+				m_nodes[i].m_area=0;
+		}
+	}
+	else
+	{
+		// initialize node area as zero
+		for(i=0,ni=m_nodes.size();i<ni;++i)
+		{
+			m_nodes[i].m_area=0;	
+		}
+
+		for(i=0,ni=m_faces.size();i<ni;++i)
+		{
+			btSoftBody::Face&	f=m_faces[i];
+
+			for(int j=0;j<3;++j)
+			{
+				f.m_n[j]->m_area += f.m_ra;
+			}
+		}
+
+		for(i=0,ni=m_nodes.size();i<ni;++i)
+		{
+			m_nodes[i].m_area *= 0.3333333f;
+		}
+	}
+}
+
+
+void				btSoftBody::updateLinkConstants()
+{	
+	int i,ni;
+
 	/* Links		*/ 
 	for(i=0,ni=m_links.size();i<ni;++i)
 	{
 		Link&		l=m_links[i];
 		Material&	m=*l.m_material;
-		l.m_rl	=	(l.m_n[0]->m_x-l.m_n[1]->m_x).length();
 		l.m_c0	=	(l.m_n[0]->m_im+l.m_n[1]->m_im)/m.m_kLST;
-		l.m_c1	=	l.m_rl*l.m_rl;
-	}
-	/* Faces		*/ 
-	for(i=0,ni=m_faces.size();i<ni;++i)
-	{
-		Face&		f=m_faces[i];
-		f.m_ra	=	AreaOf(f.m_n[0]->m_x,f.m_n[1]->m_x,f.m_n[2]->m_x);
-	}
-	/* Area's		*/ 
-	btAlignedObjectArray<int>	counts;
-	counts.resize(m_nodes.size(),0);
-	for(i=0,ni=m_nodes.size();i<ni;++i)
-	{
-		m_nodes[i].m_area	=	0;
-	}
-	for(i=0,ni=m_faces.size();i<ni;++i)
-	{
-		btSoftBody::Face&	f=m_faces[i];
-		for(int j=0;j<3;++j)
-		{
-			const int index=(int)(f.m_n[j]-&m_nodes[0]);
-			counts[index]++;
-			f.m_n[j]->m_area+=btFabs(f.m_ra);
-		}
-	}
-	for(i=0,ni=m_nodes.size();i<ni;++i)
-	{
-		if(counts[i]>0)
-			m_nodes[i].m_area/=(btScalar)counts[i];
-		else
-			m_nodes[i].m_area=0;
 	}
 }
 
+void				btSoftBody::updateConstants()
+{
+	resetLinkRestLengths();
+	updateLinkConstants();
+	updateArea();
+}
+
+
+
 //
 void					btSoftBody::initializeClusters()
 {
@@ -2820,7 +2918,7 @@ void				btSoftBody::applyForces()
 {
 
 	BT_PROFILE("SoftBody applyForces");
-	const btScalar					dt =			m_sst.sdt;
+//	const btScalar					dt =			m_sst.sdt;
 	const btScalar					kLF =			m_cfg.kLF;
 	const btScalar					kDG =			m_cfg.kDG;
 	const btScalar					kPR =			m_cfg.kPR;
@@ -2831,10 +2929,10 @@ void				btSoftBody::applyForces()
 	const bool						as_volume =		kVC>0;
 	const bool						as_aero =		as_lift	||
 													as_drag		;
-	const bool						as_vaero =		as_aero	&&
-													(m_cfg.aeromodel < btSoftBody::eAeroModel::F_TwoSided);
-	const bool						as_faero =		as_aero	&&
-													(m_cfg.aeromodel >= btSoftBody::eAeroModel::F_TwoSided);
+	//const bool						as_vaero =		as_aero	&&
+	//												(m_cfg.aeromodel < btSoftBody::eAeroModel::F_TwoSided);
+	//const bool						as_faero =		as_aero	&&
+	//												(m_cfg.aeromodel >= btSoftBody::eAeroModel::F_TwoSided);
 	const bool						use_medium =	as_aero;
 	const bool						use_volume =	as_pressure	||
 		as_volume	;
@@ -2877,7 +2975,7 @@ void				btSoftBody::applyForces()
 	/* Per face forces				*/ 
 	for(i=0,ni=m_faces.size();i<ni;++i)
 	{
-		btSoftBody::Face&	f=m_faces[i];
+	//	btSoftBody::Face&	f=m_faces[i];
 
 		/* Aerodynamics			*/ 
 		addAeroForceToFace(m_windVelocity, i);	
@@ -3068,7 +3166,7 @@ void			btSoftBody::defaultCollisionHandler(const btCollisionObjectWrapper* pcoWr
 	case	fCollision::CL_RS:
 		{
 			btSoftColliders::CollideCL_RS	collider;
-			collider.Process(this,pcoWrap);
+			collider.ProcessColObj(this,pcoWrap);
 		}
 		break;
 	}
@@ -3087,7 +3185,7 @@ void			btSoftBody::defaultCollisionHandler(btSoftBody* psb)
 			if (this!=psb || psb->m_cfg.collisions&fCollision::CL_SELF)
 			{
 				btSoftColliders::CollideCL_SS	docollide;
-				docollide.Process(this,psb);
+				docollide.ProcessSoftSoft(this,psb);
 			}
 			
 		}

src/BulletSoftBody/btSoftBody.h

@@ -671,6 +671,9 @@ public:
 	btTransform			m_initialWorldTransform;
 
 	btVector3			m_windVelocity;
+	
+	btScalar        m_restLengthScale;
+	
 	//
 	// Api
 	//
@@ -810,9 +813,15 @@ public:
 	void				rotate(	const btQuaternion& rot);
 	/* Scale																*/ 
 	void				scale(	const btVector3& scl);
+	/* Get link resting lengths scale										*/
+	btScalar			getRestLengthScale();
+	/* Scale resting length of all springs									*/
+	void				setRestLengthScale(btScalar restLength);
 	/* Set current state as pose											*/ 
 	void				setPose(		bool bvolume,
 		bool bframe);
+	/* Set current link lengths as resting lengths							*/ 
+	void				resetLinkRestLengths();
 	/* Return the volume													*/ 
 	btScalar			getVolume() const;
 	/* Cluster count														*/ 
@@ -954,6 +963,8 @@ public:
 	void				updateBounds();
 	void				updatePose();
 	void				updateConstants();
+	void				updateLinkConstants();
+	void				updateArea(bool averageArea = true);
 	void				initializeClusters();
 	void				updateClusters();
 	void				cleanupClusters();

src/BulletSoftBody/btSoftBodyInternals.h

@@ -21,6 +21,7 @@ subject to the following restrictions:
 
 
 #include "LinearMath/btQuickprof.h"
+#include "LinearMath/btPolarDecomposition.h"
 #include "BulletCollision/BroadphaseCollision/btBroadphaseInterface.h"
 #include "BulletCollision/CollisionDispatch/btCollisionDispatcher.h"
 #include "BulletCollision/CollisionShapes/btConvexInternalShape.h"
@@ -614,32 +615,8 @@ private:
 //
 static inline int			PolarDecompose(	const btMatrix3x3& m,btMatrix3x3& q,btMatrix3x3& s)
 {
-	static const btScalar	half=(btScalar)0.5;
-	static const btScalar	accuracy=(btScalar)0.0001;
-	static const int		maxiterations=16;
-	int						i=0;
-	btScalar				det=0;
-	q	=	Mul(m,1/btVector3(m[0][0],m[1][1],m[2][2]).length());
-	det	=	q.determinant();
-	if(!btFuzzyZero(det))
-	{
-		for(;i<maxiterations;++i)
-		{
-			q=Mul(Add(q,Mul(q.adjoint(),1/det).transpose()),half);
-			const btScalar	ndet=q.determinant();
-			if(Sq(ndet-det)>accuracy) det=ndet; else break;
-		}
-		/* Final orthogonalization	*/ 
-		Orthogonalize(q);
-		/* Compute 'S'				*/ 
-		s=q.transpose()*m;
-	}
-	else
-	{
-		q.setIdentity();
-		s.setIdentity();
-	}
-	return(i);
+	static const btPolarDecomposition polar;  
+	return polar.decompose(m, q, s);
 }
 
 //
@@ -753,7 +730,7 @@ struct btSoftColliders
 				}
 			}
 		}
-		void		Process(btSoftBody* ps,const btCollisionObjectWrapper* colObWrap)
+		void		ProcessColObj(btSoftBody* ps,const btCollisionObjectWrapper* colObWrap)
 		{
 			psb			=	ps;
 			m_colObjWrap			=	colObWrap;
@@ -815,7 +792,7 @@ struct btSoftColliders
 				
 			}
 		}
-		void		Process(btSoftBody* psa,btSoftBody* psb)
+		void		ProcessSoftSoft(btSoftBody* psa,btSoftBody* psb)
 		{
 			idt			=	psa->m_sst.isdt;
 			//m_margin		=	(psa->getCollisionShape()->getMargin()+psb->getCollisionShape()->getMargin())/2;

src/BulletSoftBody/btSoftRigidCollisionAlgorithm.cpp

@@ -58,8 +58,8 @@ void btSoftRigidCollisionAlgorithm::processCollision (const btCollisionObjectWra
 	(void)dispatchInfo;
 	(void)resultOut;
 	//printf("btSoftRigidCollisionAlgorithm\n");
-	const btCollisionObjectWrapper* softWrap = m_isSwapped?body1Wrap:body0Wrap;
-	const btCollisionObjectWrapper* rigidWrap = m_isSwapped?body0Wrap:body1Wrap;
+//	const btCollisionObjectWrapper* softWrap = m_isSwapped?body1Wrap:body0Wrap;
+//	const btCollisionObjectWrapper* rigidWrap = m_isSwapped?body0Wrap:body1Wrap;
 	btSoftBody* softBody =  m_isSwapped? (btSoftBody*)body1Wrap->getCollisionObject() : (btSoftBody*)body0Wrap->getCollisionObject();
 	const btCollisionObjectWrapper* rigidCollisionObjectWrap = m_isSwapped? body0Wrap : body1Wrap;