add TestHingeTorque example using btRigidBody and btHingeConstraint, setup is similar to TestJointTorque using btMultiBody and a revolute joint.

examples/Constraints/TestHingeTorque.cpp

@@ -0,0 +1,153 @@
+#include "TestHingeTorque.h"
+
+
+#include "../CommonInterfaces/CommonRigidBodyBase.h"
+#include "../CommonInterfaces/CommonParameterInterface.h"
+
+
+
+struct TestHingeTorque : public CommonRigidBodyBase
+{
+    bool m_once;
+    
+	TestHingeTorque(struct GUIHelperInterface* helper);
+	virtual ~ TestHingeTorque();
+	virtual void initPhysics();
+
+	virtual void stepSimulation(float deltaTime);
+
+	
+	virtual void resetCamera()
+	{
+    
+        float dist = 5;
+        float pitch = 270;
+        float yaw = 21;
+        float targetPos[3]={-1.34,3.4,-0.44};
+        m_guiHelper->resetCamera(dist,pitch,yaw,targetPos[0],targetPos[1],targetPos[2]);
+	}
+	
+
+};
+
+TestHingeTorque::TestHingeTorque(struct GUIHelperInterface* helper)
+:CommonRigidBodyBase(helper),
+m_once(true)
+{
+}
+TestHingeTorque::~ TestHingeTorque()
+{
+}
+
+
+void TestHingeTorque::stepSimulation(float deltaTime)
+{
+    if (m_once)
+    {
+        m_once=false;
+        btHingeConstraint* hinge = (btHingeConstraint*)m_dynamicsWorld->getConstraint(0);
+        
+        btRigidBody& bodyA = hinge->getRigidBodyA();
+        btTransform trA = bodyA.getWorldTransform();
+        btVector3 hingeAxisInWorld = trA.getBasis()*hinge->getFrameOffsetA().getBasis().getColumn(2);
+        hinge->getRigidBodyA().applyTorque(-hingeAxisInWorld*10);
+        hinge->getRigidBodyB().applyTorque(hingeAxisInWorld*10);
+        
+    }
+    
+    m_dynamicsWorld->stepSimulation(1./60,0);
+    btRigidBody* base = btRigidBody::upcast(m_dynamicsWorld->getCollisionObjectArray()[0]);
+    
+    b3Printf("base angvel = %f,%f,%f",base->getAngularVelocity()[0],
+             base->getAngularVelocity()[1],
+             
+             base->getAngularVelocity()[2]);
+    
+    btRigidBody* child = btRigidBody::upcast(m_dynamicsWorld->getCollisionObjectArray()[1]);
+    
+    b3Printf("child angvel = %f,%f,%f",child->getAngularVelocity()[0],
+             child->getAngularVelocity()[1],
+
+             child->getAngularVelocity()[2]);
+    
+    //CommonRigidBodyBase::stepSimulation(deltaTime);
+}
+
+
+
+void TestHingeTorque::initPhysics()
+{
+	m_guiHelper->setUpAxis(2);
+
+	createEmptyDynamicsWorld();
+    m_dynamicsWorld->setGravity(btVector3(0,0,0));
+    
+	m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
+	int mode = 	btIDebugDraw::DBG_DrawWireframe
+				+btIDebugDraw::DBG_DrawConstraints
+				+btIDebugDraw::DBG_DrawConstraintLimits;
+	m_dynamicsWorld->getDebugDrawer()->setDebugMode(mode);
+
+
+	{ // create a door using hinge constraint attached to the world
+        
+        int numLinks = 1;
+        bool spherical = false;					//set it ot false -to use 1DoF hinges instead of 3DoF sphericals
+        bool canSleep = false;
+        bool selfCollide = false;
+        btVector3 linkHalfExtents(0.05, 0.37, 0.1);
+        btVector3 baseHalfExtents(0.05, 0.37, 0.1);
+
+        btBoxShape* baseBox = new btBoxShape(baseHalfExtents);
+        btVector3 basePosition = btVector3(-0.4f, 3.f, 0.f);
+        btTransform baseWorldTrans;
+        baseWorldTrans.setIdentity();
+        baseWorldTrans.setOrigin(basePosition);
+        
+        //mbC->forceMultiDof();							//if !spherical, you can comment this line to check the 1DoF algorithm
+        //init the base
+        btVector3 baseInertiaDiag(0.f, 0.f, 0.f);
+        float baseMass = 1.f;
+        float linkMass = 1.f;
+        
+        btRigidBody* base = createRigidBody(baseMass,baseWorldTrans,baseBox);
+        m_dynamicsWorld->removeRigidBody(base);
+        base->setDamping(0,0);
+        m_dynamicsWorld->addRigidBody(base,0,0);
+        btBoxShape* linkBox = new btBoxShape(linkHalfExtents);
+        btRigidBody* prevBody = base;
+        
+        for (int i=0;i<numLinks;i++)
+        {
+            btTransform linkTrans;
+            linkTrans = baseWorldTrans;
+            
+            linkTrans.setOrigin(basePosition-btVector3(0,linkHalfExtents[1]*2.f*(i+1),0));
+            
+            btRigidBody* linkBody = createRigidBody(linkMass,linkTrans,linkBox);
+            m_dynamicsWorld->removeRigidBody(linkBody);
+            m_dynamicsWorld->addRigidBody(linkBody,0,0);
+            linkBody->setDamping(0,0);
+            //create a hinge constraint
+            btVector3 pivotInA(0,-linkHalfExtents[1],0);
+            btVector3 pivotInB(0,linkHalfExtents[1],0);
+            btVector3 axisInA(1,0,0);
+            btVector3 axisInB(1,0,0);
+            bool useReferenceA = true;
+            btHingeConstraint* hinge = new btHingeConstraint(*prevBody,*linkBody,
+                                                             pivotInA,pivotInB,
+                                                             axisInA,axisInB,useReferenceA);
+            m_dynamicsWorld->addConstraint(hinge,true);
+            prevBody = linkBody;
+            
+        }
+       
+	}
+	
+	m_guiHelper->autogenerateGraphicsObjects(m_dynamicsWorld);
+}
+
+class CommonExampleInterface*    TestHingeTorqueCreateFunc(CommonExampleOptions& options)
+{
+	return new TestHingeTorque(options.m_guiHelper);
+}