added LICENSE.txt and AUTHORS.txt file

add MultiBody Custom Creation example, to show how to import data from a URDF file and fill up your own data structures.
add btMultiBody::setBaseWorldTransform method
todo: fix cmake build, this patch is premake only

AUTHORS.txt

@@ -0,0 +1,39 @@
+Bullet Physics is created by Erwin Coumans with contributions from the following authors / copyright holders:
+
+AMD
+Apple
+Steve Baker
+Gino van den Bergen
+Nicola Candussi
+Erin Catto
+Lawrence Chai
+Erwin Coumans
+Christer Ericson
+Disney Animation
+Google
+Dirk Gregorius
+Marcus Hennix
+MBSim Development Team
+Takahiro Harada
+Simon Hobbs
+John Hsu
+Ole Kniemeyer
+Jay Lee
+Francisco Leon
+Vsevolod Klementjev
+Phil Knight
+John McCutchan
+Steven Peters
+Roman Ponomarev
+Nathanael Presson
+Gabor PUHR
+Arthur Shek
+Russel Smith
+Sony
+Jakub Stephien
+Marten Svanfeldt
+Pierre Terdiman
+Steven Thompson
+Tamas Umenhoffer
+
+If your name is missing, please send an email to erwin.coumans@gmail.com or file an issue at http://github.com/bulletphysics/bullet3

LICENSE.txt

@@ -0,0 +1,15 @@
+
+The files in this repository are licensed under the zlib license, except for the files under examples/ThirdPartyLibs.
+
+Bullet Continuous Collision Detection and Physics Library
+http://bulletphysics.org
+
+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.

build3/premake4.lua

@@ -121,6 +121,7 @@
 
 	include "../examples/HelloWorld"
 	include "../examples/BasicDemo"
+	include "../examples/MultiBody"
 	
 	
 	

examples/ExampleBrowser/ExampleEntries.cpp

@@ -53,7 +53,7 @@ static ExampleEntry gDefaultExamples[]=
 	ExampleEntry(0,"MultiBody",0),
 	ExampleEntry(1,"TestJointTorque",TestJointTorqueCreateFunc),
 	ExampleEntry(1,"MultiDofCreateFunc",MultiDofCreateFunc),
-	ExampleEntry(1,"Custom URDF",MultiBodyCustomURDFDofCreateFunc),
+	ExampleEntry(1,"Custom URDF",MultiBodyCustomURDFDemoCreateFunc),
 	
 
 #ifndef _DEBUG

examples/ExampleBrowser/premake4.lua

@@ -27,6 +27,10 @@
 		"../Importers/**",
 		"../Planar2D/Planar2D.*",
 		"../RenderingExamples/*",
+		"../Constraints/*",
+		"../MultiBody/MultiBodyCustomURDFDemo.cpp",
+		"../MultiBody/MultiDofDemo.cpp",
+		"../MultiBody/TestJointTorqueSetup.cpp",
 		"../ThirdPartyLibs/Wavefront/tiny_obj_loader.*",
 		"../ThirdPartyLibs/tinyxml/*",
 		"../Utils/b3Clock.*",

examples/Importers/ImportURDFDemo/ImportURDFSetup.cpp

@@ -11,22 +11,14 @@
 #include "../CommonInterfaces/CommonParameterInterface.h"
 #include "MyURDFImporter.h"
 
-static int bodyCollisionFilterGroup=btBroadphaseProxy::CharacterFilter;
-static int bodyCollisionFilterMask=btBroadphaseProxy::AllFilter&(~btBroadphaseProxy::CharacterFilter);
-static bool enableConstraints = true;//false;
+
 #include "URDF2Bullet.h"
 
-#include "urdf/urdfdom/urdf_parser/include/urdf_parser/urdf_parser.h"
 
-#include "urdf_samples.h"
+//#include "urdf_samples.h"
+
 
-//#include "BulletCollision/CollisionShapes/btCylinderShape.h"
-//#define USE_BARREL_VERTICES
-//#include "OpenGLWindow/ShapeData.h"
 
-#include <iostream>
-#include <fstream>
-using namespace urdf;
 
 
 #include "../CommonInterfaces/CommonMultiBodyBase.h"
@@ -148,32 +140,6 @@ void ImportUrdfSetup::setFileName(const char* urdfFileName)
 
 
 
-
-void printTree1(my_shared_ptr<const Link> link,int level = 0)
-{
-    level+=2;
-    int count = 0;
-    for (std::vector<my_shared_ptr<Link> >::const_iterator child = link->child_links.begin(); child != link->child_links.end(); child++)
-    {
-        if (*child)
-        {
-            for(int j=0;j<level;j++) std::cout << "  "; //indent
-            std::cout << "child(" << (count++)+1 << "):  " << (*child)->name  << std::endl;
-            // first grandchild
-            printTree1(*child,level);
-        }
-        else
-        {
-            for(int j=0;j<level;j++) std::cout << " "; //indent
-            std::cout << "root link: " << link->name << " has a null child!" << *child << std::endl;
-        }
-    }
-
-}
-
-
-
-
 void ImportUrdfSetup::initPhysics()
 {
 
@@ -194,70 +160,20 @@ void ImportUrdfSetup::initPhysics()
 	gravity[upAxis]=-9.8;
 
 	m_dynamicsWorld->setGravity(gravity);
-    //int argc=0;
-	char relativeFileName[1024];
-	
-	b3FileUtils fu;
-	printf("m_fileName=%s\n", m_fileName);
-	bool fileFound = fu.findFile(m_fileName, relativeFileName, 1024);
     
 
-	std::string xml_string;
-	char pathPrefix[1024];
-	pathPrefix[0] = 0;
-	
-    if (!fileFound){
-        std::cerr << "URDF file not found, using a dummy test URDF" << std::endl;
-        xml_string = std::string(urdf_char);
-
-    } else
-    {
-		
-		int maxPathLen = 1024;
-		fu.extractPath(relativeFileName,pathPrefix,maxPathLen);
-
-
-        std::fstream xml_file(relativeFileName, std::fstream::in);
-        while ( xml_file.good() )
-        {
-            std::string line;
-            std::getline( xml_file, line);
-            xml_string += (line + "\n");
-        }
-        xml_file.close();
-    }
-
-    my_shared_ptr<ModelInterface> robot = parseURDF(xml_string);
-    if (!robot){
-        std::cerr << "ERROR: Model Parsing the xml failed" << std::endl;
-        return ;
-    }
-    std::cout << "robot name is: " << robot->getName() << std::endl;
-
-    // get info from parser
-    std::cout << "---------- Successfully Parsed XML ---------------" << std::endl;
-    // get root link
-    my_shared_ptr<const Link> root_link=robot->getRoot();
-    if (!root_link) return ;
-
-    std::cout << "root Link: " << root_link->name << " has " << root_link->child_links.size() << " child(ren)" << std::endl;
-
-    // print entire tree
-    printTree1(root_link);
-    printf("now using new interface\n");
-    std::cout << "root Link: " << root_link->name << " has " << root_link->child_links.size() << " child(ren)" << std::endl;
 	
     //now print the tree using the new interface
-    MyURDFImporter u2b(robot,m_guiHelper);
-    printTree(u2b, 0);
+    MyURDFImporter u2b(m_guiHelper);
+	bool loadOk =  u2b.loadURDF(m_fileName);
+
+	if (loadOk)
+	{
+		u2b.printTree();
     
 		btTransform identityTrans;
 		identityTrans.setIdentity();
 	
-	int numJoints = (*robot).m_numJoints;
-
-	
-    bool useUrdfInterfaceClass = true;
 	
 		{
         
@@ -265,21 +181,17 @@ void ImportUrdfSetup::initPhysics()
 			btMultiBody* mb = 0;
         
             
-        
-            
 			//todo: move these internal API called inside the 'ConvertURDF2Bullet' call, hidden from the user
 			int rootLinkIndex = u2b.getRootLinkIndex();
 			printf("urdf root link index = %d\n",rootLinkIndex);
 			MyMultiBodyCreator creation(m_guiHelper);
 
-        ConvertURDF2Bullet(u2b,creation, identityTrans,m_dynamicsWorld,m_useMultiBody,pathPrefix);
+			ConvertURDF2Bullet(u2b,creation, identityTrans,m_dynamicsWorld,m_useMultiBody,u2b.getPathPrefix());
 			mb = creation.getBulletMultiBody();
 
 			if (m_useMultiBody)
 			{
-            mb->setHasSelfCollision(false);
-            mb->finalizeMultiDof();
-            m_dynamicsWorld->addMultiBody(mb);
+           
             
                 
 				//create motors for each joint
@@ -317,7 +229,7 @@ void ImportUrdfSetup::initPhysics()
 		//the btMultiBody support is work-in-progress :-)
 
 	
-	printf("numJoints/DOFS = %d\n", numJoints);
+	
 
 		bool createGround=true;
 		if (createGround)
@@ -341,6 +253,7 @@ void ImportUrdfSetup::initPhysics()
 
 		///this extra stepSimulation call makes sure that all the btMultibody transforms are properly propagates.
 		m_dynamicsWorld->stepSimulation(1. / 240., 0);// 1., 10, 1. / 240.);
+	}
 }
 
 void ImportUrdfSetup::stepSimulation(float deltaTime)

examples/Importers/ImportURDFDemo/MultiBodyCreationInterface.h

@@ -24,6 +24,7 @@ public:
     virtual class btMultiBodyLinkCollider* allocateMultiBodyLinkCollider(int urdfLinkIndex, int mbLinkIndex, btMultiBody* body) = 0;
     
     virtual void addLinkMapping(int urdfLinkIndex, int mbLinkIndex) = 0;
+
 };
 
 #endif //MULTIBODY_CREATION_INTERFACE_H

examples/Importers/ImportURDFDemo/MyMultiBodyCreator.cpp

@@ -69,3 +69,4 @@ btMultiBody* MyMultiBodyCreator::getBulletMultiBody()
 {
     return m_bulletMultiBody;
 }
+

examples/Importers/ImportURDFDemo/MyMultiBodyCreator.h

@@ -43,6 +43,7 @@ public:
     virtual void addLinkMapping(int urdfLinkIndex, int mbLinkIndex);
 
 	btMultiBody* getBulletMultiBody();
+
 };
 
 #endif //MY_MULTIBODY_CREATOR

examples/Importers/ImportURDFDemo/MyURDFImporter.cpp

@@ -1,3 +1,17 @@
+/* Copyright (C) 2015 Google
+
+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 "MyURDFImporter.h"
 
 
@@ -9,21 +23,58 @@
 #include "BulletCollision/CollisionShapes/btShapeHull.h"//to create a tesselation of a generic btConvexShape
 #include "../CommonInterfaces/CommonGUIHelperInterface.h"
 #include "Bullet3Common/b3FileUtils.h"
+#include <string>
 
+#include "urdf/urdfdom/urdf_parser/include/urdf_parser/urdf_parser.h"
+#include <iostream>
+#include <fstream>
 using namespace urdf;
 
 void convertURDFToVisualShape(const Visual* visual, const char* pathPrefix, const btTransform& visualTransform, btAlignedObjectArray<GLInstanceVertex>& verticesOut, btAlignedObjectArray<int>& indicesOut);
 btCollisionShape* convertURDFToCollisionShape(const Collision* visual, const char* pathPrefix);
 
 
+
+
+static void printTreeInternal(my_shared_ptr<const Link> link,int level = 0)
+{
+    level+=2;
+    int count = 0;
+    for (std::vector<my_shared_ptr<Link> >::const_iterator child = link->child_links.begin(); child != link->child_links.end(); child++)
+    {
+        if (*child)
+        {
+            for(int j=0;j<level;j++) std::cout << "  "; //indent
+            std::cout << "child(" << (count++)+1 << "):  " << (*child)->name  << std::endl;
+            // first grandchild
+            printTreeInternal(*child,level);
+        }
+        else
+        {
+            for(int j=0;j<level;j++) std::cout << " "; //indent
+            std::cout << "root link: " << link->name << " has a null child!" << *child << std::endl;
+        }
+    }
+
+}
+
+
+
+
 struct MyURDFInternalData
 {
 	my_shared_ptr<ModelInterface> m_robot;
     std::vector<my_shared_ptr<Link> > m_links;
 	struct GUIHelperInterface* m_guiHelper;
+	const char* m_pathPrefix;
 	
 };
 
+void MyURDFImporter::printTree()
+{
+	printTreeInternal(m_data->m_robot->getRoot(),0);
+}
+
 enum MyFileType
 {
 	FILE_STL=1,
@@ -33,11 +84,72 @@ enum MyFileType
 
 
     
-MyURDFImporter::MyURDFImporter(my_shared_ptr<ModelInterface> robot,struct GUIHelperInterface* helper)
+MyURDFImporter::MyURDFImporter(struct GUIHelperInterface* helper)
 {
 	m_data = new MyURDFInternalData;
-	m_data->m_robot = robot;
+	m_data->m_robot = 0;
 	m_data->m_guiHelper = helper;
+	m_data->m_pathPrefix=0;
+
+
+  
+}
+
+bool MyURDFImporter::loadURDF(const char* fileName)
+{
+
+
+//int argc=0;
+	char relativeFileName[1024];
+	
+	b3FileUtils fu;
+	
+	bool fileFound = fu.findFile(fileName, relativeFileName, 1024);
+	
+	std::string xml_string;
+	char pathPrefix[1024];
+	pathPrefix[0] = 0;
+	
+    if (!fileFound){
+        std::cerr << "URDF file not found" << std::endl;
+		return false;
+    } else
+    {
+		
+		int maxPathLen = 1024;
+		fu.extractPath(relativeFileName,pathPrefix,maxPathLen);
+
+
+        std::fstream xml_file(relativeFileName, std::fstream::in);
+        while ( xml_file.good() )
+        {
+            std::string line;
+            std::getline( xml_file, line);
+            xml_string += (line + "\n");
+        }
+        xml_file.close();
+    }
+
+    my_shared_ptr<ModelInterface> robot = parseURDF(xml_string);
+    if (!robot){
+        std::cerr << "ERROR: Model Parsing the xml failed" << std::endl;
+        return false;
+    }
+    std::cout << "robot name is: " << robot->getName() << std::endl;
+
+    // get info from parser
+    std::cout << "Successfully Parsed URDF" << std::endl;
+    // get root link
+    my_shared_ptr<const Link> root_link=robot->getRoot();
+    if (!root_link) 
+	{
+		std::cout << "Failed to find root link in URDF" << std::endl;
+		return false;
+	}
+
+
+	m_data->m_robot = robot;
+
     m_data->m_robot->getLinks(m_data->m_links);
         
     //initialize the 'index' of each link
@@ -46,8 +158,15 @@ MyURDFImporter::MyURDFImporter(my_shared_ptr<ModelInterface> robot,struct GUIHel
         m_data->m_links[i]->m_link_index = i;
     }
 
+	return true;
 }
 
+const char* MyURDFImporter::getPathPrefix()
+{
+	return m_data->m_pathPrefix;
+}
+
+
 MyURDFImporter::~MyURDFImporter()
 {
 	delete m_data;

examples/Importers/ImportURDFDemo/MyURDFImporter.h

@@ -2,9 +2,7 @@
 #define MY_URDF_IMPORTER_H 
 
 #include "URDFImporterInterface.h"
-#include <vector> //temp, replace by btAlignedObjectArray
 
-#include "urdf/urdfdom/urdf_parser/include/urdf_parser/urdf_parser.h"
 
 class MyURDFImporter : public URDFImporterInterface
 {
@@ -14,11 +12,16 @@ class MyURDFImporter : public URDFImporterInterface
 
 public:
 
-
-	MyURDFImporter(my_shared_ptr<urdf::ModelInterface> robot,struct GUIHelperInterface* helper);
+	MyURDFImporter(struct GUIHelperInterface* guiHelper);
 
 	virtual ~MyURDFImporter();
 
+	virtual bool loadURDF(const char* fileName);
+
+	const char* getPathPrefix();
+
+	void printTree(); //for debugging
+	
 	virtual int getRootLinkIndex() const;
     
     virtual void getLinkChildIndices(int linkIndex, btAlignedObjectArray<int>& childLinkIndices) const;
@@ -31,7 +34,7 @@ public:
 
     virtual bool getJointInfo(int urdfLinkIndex, btTransform& parent2joint, btVector3& jointAxisInJointSpace, int& jointType, btScalar& jointLowerLimit, btScalar& jointUpperLimit) const;
 
-	virtual int convertLinkVisualShapes(int linkIndex, const char* pathPrefix, const btTransform& inertialFrame) const;
+	virtual int convertLinkVisualShapes(int linkIndex, const char* pathPrefix, const btTransform& localInertiaFrame) const;
 
 	virtual class btCompoundShape* convertLinkCollisionShapes(int linkIndex, const char* pathPrefix, const btTransform& localInertiaFrame) const;
 

examples/Importers/ImportURDFDemo/URDF2Bullet.cpp

@@ -290,10 +290,6 @@ void ConvertURDF2BulletInternal(const URDFImporterInterface& u2b, MultiBodyCreat
                                                                rot*offsetInB.getRotation(), offsetInA.getOrigin(),-offsetInB.getOrigin(),disableParentCollision);
                         creation.addLinkMapping(urdfLinkIndex,mbLinkIndex);
                         
-                        btMatrix3x3 rm(rot);
-                        btScalar y,p,r;
-                        rm.getEulerZYX(y,p,r);
-                        printf("y=%f,p=%f,r=%f\n", y,p,r);
                                              
                     } else
                     {
@@ -505,6 +501,16 @@ void ConvertURDF2Bullet(const URDFImporterInterface& u2b, MultiBodyCreationInter
     int urdfLinkIndex = u2b.getRootLinkIndex();
     ConvertURDF2BulletInternal(u2b, creation, cache, urdfLinkIndex,rootTransformInWorldSpace,world1,createMultiBody,pathPrefix);
     
+	if (world1 && cache.m_bulletMultiBody)
+	{
+		btMultiBody* mb = cache.m_bulletMultiBody;
+		mb->setHasSelfCollision(false);
+		mb->finalizeMultiDof();
+
+		mb->setBaseWorldTransform(rootTransformInWorldSpace);
+
+		world1->addMultiBody(mb);
+	}
 }
 
 

examples/Importers/ImportURDFDemo/URDF2Bullet.h

@@ -16,7 +16,6 @@ class MultiBodyCreationInterface;
 void printTree(const URDFImporterInterface& u2b, int linkIndex, int identationLevel=0);
 
 
-
 void ConvertURDF2Bullet(const URDFImporterInterface& u2b, 
 			MultiBodyCreationInterface& creationCallback, 
 			const btTransform& rootTransformInWorldSpace, 
@@ -24,5 +23,6 @@ void ConvertURDF2Bullet(const URDFImporterInterface& u2b,
 			bool createMultiBody, 
 			const char* pathPrefix);
 
+
 #endif //_URDF2BULLET_H
 

examples/MultiBody/CustomMultiBodyCreationCallback.h

@@ -1,3 +1,17 @@
+/* Copyright (C) 2015 Google
+
+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.
+*/
+
+
 #ifndef CUSTOM_MULTIBODY_CALLBACK_H
 #define CUSTOM_MULTIBODY_CALLBACK_H
 

examples/MultiBody/MultiBodyCustomURDFDemo.cpp

@@ -1,3 +1,15 @@
+/* Copyright (C) 2015 Google
+
+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 "MultiBodyCustomURDFDemo.h"
 
@@ -6,6 +18,9 @@
 #include "../CommonInterfaces/CommonMultiBodyBase.h"
 
 #include "../Importers/ImportURDFDemo/URDF2Bullet.h"
+#include "../Importers/ImportURDFDemo/MyURDFImporter.h"
+#include "../Importers/ImportURDFDemo/MyMultiBodyCreator.h"
+
 #include "CustomMultiBodyCreationCallback.h"
 
 
@@ -34,31 +49,100 @@ MultiBodyCustomURDFDemo::~MultiBodyCustomURDFDemo()
 
 }
 
+
+static void myPrintTree(const URDFImporterInterface& u2b, int linkIndex, int indentationLevel)
+{
+    btAlignedObjectArray<int> childIndices;
+    u2b.getLinkChildIndices(linkIndex,childIndices);
+    
+    int numChildren = childIndices.size();
+    
+    indentationLevel+=2;
+    int count = 0;
+    for (int i=0;i<numChildren;i++)
+    {
+        int childLinkIndex = childIndices[i];
+        std::string name = u2b.getLinkName(childLinkIndex);
+        for(int j=0;j<indentationLevel;j++) printf("  "); //indent
+        printf("child(%d).name=%s with childIndex=%d\n",(count++)+1, name.c_str(),childLinkIndex);
+        // first grandchild
+        printTree(u2b,childLinkIndex,indentationLevel);
+    }
+}
+
+
+
+
+class TestMultiBodyCreationCallback : public CustomMultiBodyCreationCallback
+{
+	virtual int allocateMultiBodyBase(int urdfLinkIndex, int totalNumJoints,ScalarType baseMass, const Vector3dType& localInertiaDiagonal, bool isFixedBase)
+	{
+		printf("added base\n");
+	}
+
+    virtual void addLinkAndJoint(int jointType, int linkIndex,            // 0 to num_links-1
+                       int parentIndex,
+                       double mass,
+                       const Vector3dType&	inertia,
+                       const QuaternionType &rotParentFrameToLinkFrame,  // rotate points in parent frame to this frame, when q = 0
+                       const Vector3dType&	jointAxisInLinkFrame,    // in Link frame
+                       const Vector3dType&	parentComToThisJointOffset,    // vector from parent COM to joint frame, in Parent frame
+                       const Vector3dType&	thisJointToThisComOffset)       // vector from joint frame to my COM, in Link frame);
+	{
+		printf("added link\n");
+	}
+                 
+};
+
 void MultiBodyCustomURDFDemo::initPhysics()
 {
     int upAxis = 2;
     m_guiHelper->setUpAxis(upAxis);
 	createEmptyDynamicsWorld();
+	btVector3 grav(0,0,0);
+	//grav[upAxis] = -10.f;
+
+	m_dynamicsWorld->setGravity(grav);
+
     m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
-    m_dynamicsWorld->getDebugDrawer()->setDebugMode(
-        //btIDebugDraw::DBG_DrawConstraints
-        +btIDebugDraw::DBG_DrawWireframe
-        +btIDebugDraw::DBG_DrawContactPoints
-        +btIDebugDraw::DBG_DrawAabb
-        );//+btIDebugDraw::DBG_DrawConstraintLimits);
 
 
 	
+    MyURDFImporter u2b(m_guiHelper);
+	bool loadOk =  u2b.loadURDF("r2d2.urdf");
+
+	if (loadOk)
+	{
+		u2b.printTree();
+		int urdfRootLinkIndex = u2b.getRootLinkIndex();
+		myPrintTree(u2b,urdfRootLinkIndex,0);
+
+		btTransform identityTrans;
+		identityTrans.setIdentity();
+	
+		btMultiBody* mb = 0;
+        
+
+		//todo: move these internal API called inside the 'ConvertURDF2Bullet' call, hidden from the user
+		int rootLinkIndex = u2b.getRootLinkIndex();
+		printf("urdf root link index = %d\n",rootLinkIndex);
+		MyMultiBodyCreator creation(m_guiHelper);
+
+		bool useMultiBody = true;
+
+		ConvertURDF2Bullet(u2b,creation, identityTrans,m_dynamicsWorld,useMultiBody,u2b.getPathPrefix());
+		mb = creation.getBulletMultiBody();
+
+	}
 }
 
 void MultiBodyCustomURDFDemo::stepSimulation(float deltaTime)
 {
-   
     m_dynamicsWorld->stepSimulation(deltaTime);
 }
 
 
-class ExampleInterface*    MultiBodyCustomURDFDofCreateFunc(struct PhysicsInterface* pint, struct GUIHelperInterface* helper, int option)
+class ExampleInterface*    MultiBodyCustomURDFDemoCreateFunc(struct PhysicsInterface* pint, struct GUIHelperInterface* helper, int option)
 {
 	return new MultiBodyCustomURDFDemo(helper);
 }

examples/MultiBody/MultiBodyCustomURDFDemo.h

@@ -1,6 +1,20 @@
+/* Copyright (C) 2015 Google
+
+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.
+*/
+
+
 #ifndef MULTI_DOF_CUSTOM_URDF_DEMO_H
 #define MULTI_DOF_CUSTOM_URDF_DEMO_H
 
-class ExampleInterface*    MultiBodyCustomURDFDofCreateFunc(struct PhysicsInterface* pint, struct GUIHelperInterface* helper, int option);
+class ExampleInterface*    MultiBodyCustomURDFDemoCreateFunc(struct PhysicsInterface* pint, struct GUIHelperInterface* helper, int option);
 
 #endif //MULTI_DOF_CUSTOM_URDF_DEMO_H

examples/MultiBody/main.cpp

@@ -0,0 +1,43 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2015 Google Inc. http://bulletphysics.org
+
+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 "MultiBodyCustomURDFDemo.h"
+
+#include "../CommonInterfaces/ExampleInterface.h"
+#include "../CommonInterfaces/CommonGUIHelperInterface.h"
+
+
+
+
+int main(int argc, char* argv[])
+{
+	struct PhysicsInterface* pint = 0;
+	
+	DummyGUIHelper noGfx;
+
+	int option = 0;
+
+	ExampleInterface*    example = MultiBodyCustomURDFDemoCreateFunc(pint, &noGfx, option);
+	
+	example->initPhysics();
+	example->stepSimulation(1.f/60.f);
+	example->exitPhysics();
+
+	delete example;
+
+	return 0;
+}
+

examples/MultiBody/premake4.lua

@@ -0,0 +1,40 @@
+
+project "App_CustomMultiBodyCreation"
+
+if _OPTIONS["ios"] then
+	kind "WindowedApp"
+else	
+	kind "ConsoleApp"
+end
+
+includedirs {".", "../../src",  "../ThirdPartyLibs"}
+
+links {
+	"Bullet3Common", "BulletDynamics","BulletCollision", "LinearMath"
+}
+
+language "C++"
+
+files {
+	"MultiBodyCustomURDFDemo.cpp",
+	"main.cpp",
+	"../Importers/ImportURDFDemo/URDF2Bullet.cpp",
+	"../Importers/ImportURDFDemo/MyURDFImporter.cpp",
+	"../Importers/ImportURDFDemo/MyMultiBodyCreator.cpp",
+	"../Importers/ImportObjDemo/LoadMeshFromObj.cpp",
+	"../Importers/ImportObjDemo/Wavefront2GLInstanceGraphicsShape.cpp",
+	"../Importers/ImportColladaDemo/LoadMeshFromCollada.cpp",
+	"../ThirdPartyLibs/Wavefront/tiny_obj_loader.cpp",
+	"../ThirdPartyLibs/tinyxml/tinystr.cpp",
+	"../ThirdPartyLibs/tinyxml/tinyxml.cpp",
+	"../ThirdPartyLibs/tinyxml/tinyxmlparser.cpp",
+	"../ThirdPartyLibs/tinyxml/tinyxmlerror.cpp",
+	"../ThirdPartyLibs/urdf/boost_replacement/printf_console.cpp",
+	"../ThirdPartyLibs/urdf/boost_replacement/string_split.cpp",
+	"../ThirdPartyLibs/urdf/urdfdom/urdf_parser/src/pose.cpp",
+	"../ThirdPartyLibs/urdf/urdfdom/urdf_parser/src/model.cpp",
+	"../ThirdPartyLibs/urdf/urdfdom/urdf_parser/src/link.cpp",
+	"../ThirdPartyLibs/urdf/urdfdom/urdf_parser/src/joint.cpp",
+	
+}
+

src/BulletDynamics/Featherstone/btMultiBody.h

@@ -178,6 +178,13 @@ public:
 	{ 
 		m_basePos = pos; 
 	}
+
+	void setBaseWorldTransform(const btTransform& tr)
+	{
+		setBasePos(tr.getOrigin());
+		setWorldToBaseRot(tr.getRotation().inverse());
+
+	}
     void setBaseVel(const btVector3 &vel) 
 	{