Enable 'global absolute velocities' by default for btMultiBody. See 8.3.2B Proposed resolution Jakub Stepien PhD Thesis

https://drive.google.com/file/d/0Bz3vEa19XOYGNWdZWGpMdUdqVmZ5ZVBOaEh4ZnpNaUxxZFNV/view?usp=sharing
Fixes crashes due to rendering of softbody wireframe in the wrong thread (needs to be in 'debug' rendering section)
Use btCapsuleShapeZ instead of btMultiSphereShape when converting MJCF MuJoCo capsules using fromto

examples/Importers/ImportMJCFDemo/BulletMJCFImporter.cpp

@@ -1897,6 +1897,7 @@ class btCompoundShape* BulletMJCFImporter::convertLinkCollisionShapes( int linkI
 			{
 				if (col->m_geometry.m_hasFromTo)
 				{
+#if 0
 					btVector3 f = col->m_geometry.m_capsuleFrom;
 					btVector3 t = col->m_geometry.m_capsuleTo;
 					btVector3 fromto[2] = {f,t};
@@ -1905,6 +1906,34 @@ class btCompoundShape* BulletMJCFImporter::convertLinkCollisionShapes( int linkI
 
 					btMultiSphereShape* ms = new btMultiSphereShape(fromto,radii,2);
 					childShape = ms;
+#else
+						btVector3 f = col->m_geometry.m_capsuleFrom;
+					btVector3 t = col->m_geometry.m_capsuleTo;
+					
+					//compute the local 'fromto' transform
+					btVector3 localPosition = btScalar(0.5)*(t+f);
+					btQuaternion localOrn;
+					localOrn = btQuaternion::getIdentity();
+
+					btVector3 diff = t-f;
+					btScalar lenSqr = diff.length2();
+					btScalar height = 0.f;
+
+					if (lenSqr > SIMD_EPSILON)
+					{
+						height = btSqrt(lenSqr);
+						btVector3 ax = diff / height;
+
+						btVector3 zAxis(0,0,1);
+						localOrn = shortestArcQuat(zAxis,ax);
+					}
+					btCapsuleShapeZ* capsule= new btCapsuleShapeZ(col->m_geometry.m_capsuleRadius,height);
+
+					btCompoundShape* compound = new btCompoundShape();
+					btTransform localTransform(localOrn,localPosition);
+					compound->addChildShape(localTransform,capsule);
+					childShape = compound;
+#endif
 				} else
 				{
 					btCapsuleShapeZ* cap = new btCapsuleShapeZ(col->m_geometry.m_capsuleRadius,

examples/Importers/ImportURDFDemo/URDF2Bullet.cpp

@@ -344,6 +344,10 @@ void ConvertURDF2BulletInternal(
                 bool isFixedBase = (mass==0);//todo: figure out when base is fixed
                 int totalNumJoints = cache.m_totalNumJoints1;
                 cache.m_bulletMultiBody = creation.allocateMultiBody(urdfLinkIndex, totalNumJoints,mass, localInertiaDiagonal, isFixedBase, canSleep);
+				if (flags & CUF_NO_GLOBAL_VELOCITIES_MB)
+				{
+					cache.m_bulletMultiBody->useGlobalVelocities(false);
+				}
 				if (flags & CUF_USE_MJCF)
 				{
 					cache.m_bulletMultiBody->setBaseWorldTransform(linkTransformInWorldSpace);

examples/Importers/ImportURDFDemo/URDF2Bullet.h

@@ -24,6 +24,7 @@ enum ConvertURDFFlags {
   CUF_USE_SELF_COLLISION_EXCLUDE_ALL_PARENTS=32,
   CUF_RESERVED=64,
   CUF_USE_IMPLICIT_CYLINDER=128,
+  CUF_NO_GLOBAL_VELOCITIES_MB=256,
 };
 
 void ConvertURDF2Bullet(const URDFImporterInterface& u2b,