Merge pull request #350 from erwincoumans/masterold_demos

maintain backward compatibility using BT_ENABLE_GYROPSCOPIC_FORCE = BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY

14 files changed, 631 insertions, 128 deletions

diff --git a/Demos/ForkLiftDemo/ForkLiftPhysicsSetup.cpp b/Demos/ForkLiftDemo/ForkLiftPhysicsSetup.cpp
new file mode 100644
index 000000000..edb556828
--- /dev/null
+++ b/Demos/ForkLiftDemo/ForkLiftPhysicsSetup.cpp
@@ -0,0 +1,503 @@
+#include "ForkLiftPhysicsSetup.h"
+#include "BulletDynamics/MLCPSolvers/btDantzigSolver.h"
+#include "BulletDynamics/MLCPSolvers/btSolveProjectedGaussSeidel.h"
+#include "BulletDynamics/MLCPSolvers/btMLCPSolver.h"
+#include "OpenGLWindow/CommonRenderInterface.h"
+
+btScalar maxMotorImpulse = 1400.f;
+btScalar loadMass = 350.f;//
+#ifdef FORCE_ZAXIS_UP
+		int rightIndex = 0; 
+		int upIndex = 2; 
+		int forwardIndex = 1;
+		btVector3 wheelDirectionCS0(0,0,-1);
+		btVector3 wheelAxleCS(1,0,0);
+#else
+		int rightIndex = 0;
+		int upIndex = 1;
+		int forwardIndex = 2;
+		btVector3 wheelDirectionCS0(0,-1,0);
+		btVector3 wheelAxleCS(-1,0,0);
+#endif
+
+float	defaultBreakingForce = 10.f;
+float	gBreakingForce = 100.f;
+float	gEngineForce = 0.f;
+float	gVehicleSteering = 0.f;
+float	steeringIncrement = 0.04f;
+float	steeringClamp = 0.3f;
+float	wheelRadius = 0.5f;
+float	wheelWidth = 0.4f;
+btScalar suspensionRestLength(0.6);
+#define CUBE_HALF_EXTENTS 1
+float	suspensionStiffness = 20.f;
+float	suspensionDamping = 2.3f;
+float	suspensionCompression = 4.4f;
+float	rollInfluence = 0.1f;//1.0f;
+float	wheelFriction = 1000;//BT_LARGE_FLOAT;
+
+
+struct ForkLiftInternalData
+{
+	btRigidBody* m_carChassis;
+
+//----------------------------
+	btRigidBody* m_liftBody;
+	btVector3	m_liftStartPos;
+	btHingeConstraint* m_liftHinge;
+	btRigidBody* m_forkBody;
+	btVector3	m_forkStartPos;
+	btSliderConstraint* m_forkSlider;
+	btRigidBody* m_loadBody;
+	btVector3	m_loadStartPos;
+	bool m_useDefaultCamera;
+	class btTriangleIndexVertexArray*	m_indexVertexArrays;
+	btVector3*	m_vertices;
+	btRaycastVehicle::btVehicleTuning	m_tuning;
+	btVehicleRaycaster*	m_vehicleRayCaster;
+	btRaycastVehicle*	m_vehicle;
+	btCollisionShape*	m_wheelShape;
+	float		m_cameraHeight;
+	float	m_minCameraDistance;
+	float	m_maxCameraDistance;
+	btAlignedObjectArray<btCollisionShape*> m_collisionShapes;
+	class btBroadphaseInterface*	m_overlappingPairCache;
+	class btCollisionDispatcher*	m_dispatcher;
+	class btConstraintSolver*	m_constraintSolver;
+	class btDefaultCollisionConfiguration* m_collisionConfiguration;
+	class btDiscreteDynamicsWorld* m_dynamicsWorld;
+
+	int m_wheelInstances[4];
+
+	bool useMCLPSolver;
+
+	ForkLiftInternalData()
+		:m_carChassis(0),
+		m_liftBody(0),
+		m_forkBody(0),
+		m_loadBody(0),
+		m_indexVertexArrays(0),
+		m_vertices(0),
+		m_cameraHeight(4.f),
+		m_minCameraDistance(3.f),
+		m_maxCameraDistance(10.f),
+		m_overlappingPairCache(0),
+		m_dispatcher(0),
+		m_constraintSolver(0),
+		m_collisionConfiguration(0),
+		m_dynamicsWorld(0),
+		useMCLPSolver(false)
+	{
+		m_vehicle = 0;
+		m_wheelShape = 0;
+		m_useDefaultCamera = false;
+	}
+};
+
+ForkLiftPhysicsSetup::ForkLiftPhysicsSetup()
+{
+	m_data = new ForkLiftInternalData;
+}
+
+ForkLiftPhysicsSetup::~ForkLiftPhysicsSetup()
+{
+	delete m_data;
+}
+
+	
+void ForkLiftPhysicsSetup::initPhysics(GraphicsPhysicsBridge& gfxBridge)
+{
+
+	
+#ifdef FORCE_ZAXIS_UP
+	m_cameraUp = btVector3(0,0,1);
+	m_forwardAxis = 1;
+#endif
+
+	btCollisionShape* groundShape = new btBoxShape(btVector3(50,3,50));
+	m_data->m_collisionShapes.push_back(groundShape);
+	m_data->m_collisionConfiguration = new btDefaultCollisionConfiguration();
+	m_data->m_dispatcher = new btCollisionDispatcher(m_data->m_collisionConfiguration);
+	btVector3 worldMin(-1000,-1000,-1000);
+	btVector3 worldMax(1000,1000,1000);
+	m_data->m_overlappingPairCache = new btAxisSweep3(worldMin,worldMax);
+	if (m_data->useMCLPSolver)
+	{
+		btDantzigSolver* mlcp = new btDantzigSolver();
+		//btSolveProjectedGaussSeidel* mlcp = new btSolveProjectedGaussSeidel;
+		btMLCPSolver* sol = new btMLCPSolver(mlcp);
+		m_data->m_constraintSolver = sol;
+	} else
+	{
+		m_data->m_constraintSolver = new btSequentialImpulseConstraintSolver();
+	}
+	m_data->m_dynamicsWorld = new btDiscreteDynamicsWorld(m_data->m_dispatcher,m_data->m_overlappingPairCache,m_data->m_constraintSolver,m_data->m_collisionConfiguration);
+	if (m_data->useMCLPSolver)
+	{
+		m_data->m_dynamicsWorld ->getSolverInfo().m_minimumSolverBatchSize = 1;//for direct solver it is better to have a small A matrix
+	} else
+	{
+		m_data->m_dynamicsWorld ->getSolverInfo().m_minimumSolverBatchSize = 128;//for direct solver, it is better to solve multiple objects together, small batches have high overhead
+	}
+#ifdef FORCE_ZAXIS_UP
+	m_dynamicsWorld->setGravity(btVector3(0,0,-10));
+#endif 
+
+	//m_dynamicsWorld->setGravity(btVector3(0,0,0));
+btTransform tr;
+tr.setIdentity();
+tr.setOrigin(btVector3(0,-3,0));
+
+//either use heightfield or triangle mesh
+
+
+	//create ground object
+	localCreateRigidBody(0,tr,groundShape);
+
+#ifdef FORCE_ZAXIS_UP
+//   indexRightAxis = 0; 
+//   indexUpAxis = 2; 
+//   indexForwardAxis = 1; 
+	btCollisionShape* chassisShape = new btBoxShape(btVector3(1.f,2.f, 0.5f));
+	btCompoundShape* compound = new btCompoundShape();
+	btTransform localTrans;
+	localTrans.setIdentity();
+	//localTrans effectively shifts the center of mass with respect to the chassis
+	localTrans.setOrigin(btVector3(0,0,1));
+#else
+	btCollisionShape* chassisShape = new btBoxShape(btVector3(1.f,0.5f,2.f));
+	m_data->m_collisionShapes.push_back(chassisShape);
+
+	btCompoundShape* compound = new btCompoundShape();
+	m_data->m_collisionShapes.push_back(compound);
+	btTransform localTrans;
+	localTrans.setIdentity();
+	//localTrans effectively shifts the center of mass with respect to the chassis
+	localTrans.setOrigin(btVector3(0,1,0));
+#endif
+
+	compound->addChildShape(localTrans,chassisShape);
+
+	{
+		btCollisionShape* suppShape = new btBoxShape(btVector3(0.5f,0.1f,0.5f));
+		btTransform suppLocalTrans;
+		suppLocalTrans.setIdentity();
+		//localTrans effectively shifts the center of mass with respect to the chassis
+		suppLocalTrans.setOrigin(btVector3(0,1.0,2.5));
+		compound->addChildShape(suppLocalTrans, suppShape);
+	}
+
+	tr.setOrigin(btVector3(0,0.f,0));
+
+	m_data->m_carChassis = localCreateRigidBody(800,tr,compound);//chassisShape);
+	//m_carChassis->setDamping(0.2,0.2);
+	
+	m_data->m_wheelShape = new btCylinderShapeX(btVector3(wheelWidth,wheelRadius,wheelRadius));
+	gfxBridge.createCollisionShapeGraphicsObject(m_data->m_wheelShape);
+	int wheelGraphicsIndex = m_data->m_wheelShape->getUserIndex();
+
+	const float position[4]={0,10,10,0};
+	const float quaternion[4]={0,0,0,1};
+	const float color[4]={0,1,0,1};
+	const float scaling[4] = {1,1,1,1};
+
+	for (int i=0;i<4;i++)
+	{
+		m_data->m_wheelInstances[i] = gfxBridge.registerGraphicsInstance(wheelGraphicsIndex, position, quaternion, color, scaling);
+	}
+
+
+	{
+		btCollisionShape* liftShape = new btBoxShape(btVector3(0.5f,2.0f,0.05f));
+		m_data->m_collisionShapes.push_back(liftShape);
+		btTransform liftTrans;
+		m_data->m_liftStartPos = btVector3(0.0f, 2.5f, 3.05f);
+		liftTrans.setIdentity();
+		liftTrans.setOrigin(m_data->m_liftStartPos);
+		m_data->m_liftBody = localCreateRigidBody(10,liftTrans, liftShape);
+
+		btTransform localA, localB;
+		localA.setIdentity();
+		localB.setIdentity();
+		localA.getBasis().setEulerZYX(0, SIMD_HALF_PI, 0);
+		localA.setOrigin(btVector3(0.0, 1.0, 3.05));
+		localB.getBasis().setEulerZYX(0, SIMD_HALF_PI, 0);
+		localB.setOrigin(btVector3(0.0, -1.5, -0.05));
+		m_data->m_liftHinge = new btHingeConstraint(*m_data->m_carChassis,*m_data->m_liftBody, localA, localB);
+//		m_liftHinge->setLimit(-LIFT_EPS, LIFT_EPS);
+		m_data->m_liftHinge->setLimit(0.0f, 0.0f);
+		m_data->m_dynamicsWorld->addConstraint(m_data->m_liftHinge, true);
+
+		btCollisionShape* forkShapeA = new btBoxShape(btVector3(1.0f,0.1f,0.1f));
+		m_data->m_collisionShapes.push_back(forkShapeA);
+		btCompoundShape* forkCompound = new btCompoundShape();
+		m_data->m_collisionShapes.push_back(forkCompound);
+		btTransform forkLocalTrans;
+		forkLocalTrans.setIdentity();
+		forkCompound->addChildShape(forkLocalTrans, forkShapeA);
+
+		btCollisionShape* forkShapeB = new btBoxShape(btVector3(0.1f,0.02f,0.6f));
+		m_data->m_collisionShapes.push_back(forkShapeB);
+		forkLocalTrans.setIdentity();
+		forkLocalTrans.setOrigin(btVector3(-0.9f, -0.08f, 0.7f));
+		forkCompound->addChildShape(forkLocalTrans, forkShapeB);
+
+		btCollisionShape* forkShapeC = new btBoxShape(btVector3(0.1f,0.02f,0.6f));
+		m_data->m_collisionShapes.push_back(forkShapeC);
+		forkLocalTrans.setIdentity();
+		forkLocalTrans.setOrigin(btVector3(0.9f, -0.08f, 0.7f));
+		forkCompound->addChildShape(forkLocalTrans, forkShapeC);
+
+		btTransform forkTrans;
+		m_data->m_forkStartPos = btVector3(0.0f, 0.6f, 3.2f);
+		forkTrans.setIdentity();
+		forkTrans.setOrigin(m_data->m_forkStartPos);
+		m_data->m_forkBody = localCreateRigidBody(5, forkTrans, forkCompound);
+
+		localA.setIdentity();
+		localB.setIdentity();
+		localA.getBasis().setEulerZYX(0, 0, SIMD_HALF_PI);
+		localA.setOrigin(btVector3(0.0f, -1.9f, 0.05f));
+		localB.getBasis().setEulerZYX(0, 0, SIMD_HALF_PI);
+		localB.setOrigin(btVector3(0.0, 0.0, -0.1));
+		m_data->m_forkSlider = new btSliderConstraint(*m_data->m_liftBody, *m_data->m_forkBody, localA, localB, true);
+		m_data->m_forkSlider->setLowerLinLimit(0.1f);
+		m_data->m_forkSlider->setUpperLinLimit(0.1f);
+//		m_forkSlider->setLowerAngLimit(-LIFT_EPS);
+//		m_forkSlider->setUpperAngLimit(LIFT_EPS);
+		m_data->m_forkSlider->setLowerAngLimit(0.0f);
+		m_data->m_forkSlider->setUpperAngLimit(0.0f);
+		m_data->m_dynamicsWorld->addConstraint(m_data->m_forkSlider, true);
+
+
+		btCompoundShape* loadCompound = new btCompoundShape();
+		m_data->m_collisionShapes.push_back(loadCompound);
+		btCollisionShape* loadShapeA = new btBoxShape(btVector3(2.0f,0.5f,0.5f));
+		m_data->m_collisionShapes.push_back(loadShapeA);
+		btTransform loadTrans;
+		loadTrans.setIdentity();
+		loadCompound->addChildShape(loadTrans, loadShapeA);
+		btCollisionShape* loadShapeB = new btBoxShape(btVector3(0.1f,1.0f,1.0f));
+		m_data->m_collisionShapes.push_back(loadShapeB);
+		loadTrans.setIdentity();
+		loadTrans.setOrigin(btVector3(2.1f, 0.0f, 0.0f));
+		loadCompound->addChildShape(loadTrans, loadShapeB);
+		btCollisionShape* loadShapeC = new btBoxShape(btVector3(0.1f,1.0f,1.0f));
+		m_data->m_collisionShapes.push_back(loadShapeC);
+		loadTrans.setIdentity();
+		loadTrans.setOrigin(btVector3(-2.1f, 0.0f, 0.0f));
+		loadCompound->addChildShape(loadTrans, loadShapeC);
+		loadTrans.setIdentity();
+		m_data->m_loadStartPos = btVector3(0.0f, 3.5f, 7.0f);
+		loadTrans.setOrigin(m_data->m_loadStartPos);
+		m_data->m_loadBody  = localCreateRigidBody(loadMass, loadTrans, loadCompound);
+	}
+
+
+
+	
+	
+	/// create vehicle
+	{
+		
+		m_data->m_vehicleRayCaster = new btDefaultVehicleRaycaster(m_data->m_dynamicsWorld);
+		m_data->m_vehicle = new btRaycastVehicle(m_data->m_tuning,m_data->m_carChassis,m_data->m_vehicleRayCaster);
+		
+		///never deactivate the vehicle
+		m_data->m_carChassis->setActivationState(DISABLE_DEACTIVATION);
+
+		m_data->m_dynamicsWorld->addVehicle(m_data->m_vehicle);
+
+		float connectionHeight = 1.2f;
+
+	
+		bool isFrontWheel=true;
+
+		//choose coordinate system
+		m_data->m_vehicle->setCoordinateSystem(rightIndex,upIndex,forwardIndex);
+
+#ifdef FORCE_ZAXIS_UP
+		btVector3 connectionPointCS0(CUBE_HALF_EXTENTS-(0.3*wheelWidth),2*CUBE_HALF_EXTENTS-wheelRadius, connectionHeight);
+#else
+		btVector3 connectionPointCS0(CUBE_HALF_EXTENTS-(0.3*wheelWidth),connectionHeight,2*CUBE_HALF_EXTENTS-wheelRadius);
+#endif
+
+		m_data->m_vehicle->addWheel(connectionPointCS0,wheelDirectionCS0,wheelAxleCS,suspensionRestLength,wheelRadius,m_data->m_tuning,isFrontWheel);
+#ifdef FORCE_ZAXIS_UP
+		connectionPointCS0 = btVector3(-CUBE_HALF_EXTENTS+(0.3*wheelWidth),2*CUBE_HALF_EXTENTS-wheelRadius, connectionHeight);
+#else
+		connectionPointCS0 = btVector3(-CUBE_HALF_EXTENTS+(0.3*wheelWidth),connectionHeight,2*CUBE_HALF_EXTENTS-wheelRadius);
+#endif
+
+		m_data->m_vehicle->addWheel(connectionPointCS0,wheelDirectionCS0,wheelAxleCS,suspensionRestLength,wheelRadius,m_data->m_tuning,isFrontWheel);
+#ifdef FORCE_ZAXIS_UP
+		connectionPointCS0 = btVector3(-CUBE_HALF_EXTENTS+(0.3*wheelWidth),-2*CUBE_HALF_EXTENTS+wheelRadius, connectionHeight);
+#else
+		connectionPointCS0 = btVector3(-CUBE_HALF_EXTENTS+(0.3*wheelWidth),connectionHeight,-2*CUBE_HALF_EXTENTS+wheelRadius);
+#endif //FORCE_ZAXIS_UP
+		isFrontWheel = false;
+		m_data->m_vehicle->addWheel(connectionPointCS0,wheelDirectionCS0,wheelAxleCS,suspensionRestLength,wheelRadius,m_data->m_tuning,isFrontWheel);
+#ifdef FORCE_ZAXIS_UP
+		connectionPointCS0 = btVector3(CUBE_HALF_EXTENTS-(0.3*wheelWidth),-2*CUBE_HALF_EXTENTS+wheelRadius, connectionHeight);
+#else
+		connectionPointCS0 = btVector3(CUBE_HALF_EXTENTS-(0.3*wheelWidth),connectionHeight,-2*CUBE_HALF_EXTENTS+wheelRadius);
+#endif
+		m_data->m_vehicle->addWheel(connectionPointCS0,wheelDirectionCS0,wheelAxleCS,suspensionRestLength,wheelRadius,m_data->m_tuning,isFrontWheel);
+		
+		for (int i=0;i<m_data->m_vehicle->getNumWheels();i++)
+		{
+			btWheelInfo& wheel = m_data->m_vehicle->getWheelInfo(i);
+			wheel.m_suspensionStiffness = suspensionStiffness;
+			wheel.m_wheelsDampingRelaxation = suspensionDamping;
+			wheel.m_wheelsDampingCompression = suspensionCompression;
+			wheel.m_frictionSlip = wheelFriction;
+			wheel.m_rollInfluence = rollInfluence;
+		}
+	}
+
+	resetForklift();
+	gfxBridge.autogenerateGraphicsObjects(m_data->m_dynamicsWorld);
+
+//	setCameraDistance(26.f);
+}
+
+void ForkLiftPhysicsSetup::resetForklift()
+{
+	gVehicleSteering = 0.f;
+	gBreakingForce = defaultBreakingForce;
+	gEngineForce = 0.f;
+
+	m_data->m_carChassis->setCenterOfMassTransform(btTransform::getIdentity());
+	m_data->m_carChassis->setLinearVelocity(btVector3(0,0,0));
+	m_data->m_carChassis->setAngularVelocity(btVector3(0,0,0));
+	m_data->m_dynamicsWorld->getBroadphase()->getOverlappingPairCache()->cleanProxyFromPairs(m_data->m_carChassis->getBroadphaseHandle(),m_data->m_dynamicsWorld->getDispatcher());
+	if (m_data->m_vehicle)
+	{
+		m_data->m_vehicle->resetSuspension();
+		for (int i=0;i<m_data->m_vehicle->getNumWheels();i++)
+		{
+			//synchronize the wheels with the (interpolated) chassis worldtransform
+			m_data->m_vehicle->updateWheelTransform(i,true);
+		}
+	}
+	btTransform liftTrans;
+	liftTrans.setIdentity();
+	liftTrans.setOrigin(m_data->m_liftStartPos);
+	m_data->m_liftBody->activate();
+	m_data->m_liftBody->setCenterOfMassTransform(liftTrans);
+	m_data->m_liftBody->setLinearVelocity(btVector3(0,0,0));
+	m_data->m_liftBody->setAngularVelocity(btVector3(0,0,0));
+
+	btTransform forkTrans;
+	forkTrans.setIdentity();
+	forkTrans.setOrigin(m_data->m_forkStartPos);
+	m_data->m_forkBody->activate();
+	m_data->m_forkBody->setCenterOfMassTransform(forkTrans);
+	m_data->m_forkBody->setLinearVelocity(btVector3(0,0,0));
+	m_data->m_forkBody->setAngularVelocity(btVector3(0,0,0));
+
+//	m_liftHinge->setLimit(-LIFT_EPS, LIFT_EPS);
+	m_data->m_liftHinge->setLimit(0.0f, 0.0f);
+	m_data->m_liftHinge->enableAngularMotor(false, 0, 0);
+
+	
+	m_data->m_forkSlider->setLowerLinLimit(0.1f);
+	m_data->m_forkSlider->setUpperLinLimit(0.1f);
+	m_data->m_forkSlider->setPoweredLinMotor(false);
+
+	btTransform loadTrans;
+	loadTrans.setIdentity();
+	loadTrans.setOrigin(m_data->m_loadStartPos);
+	m_data->m_loadBody->activate();
+	m_data->m_loadBody->setCenterOfMassTransform(loadTrans);
+	m_data->m_loadBody->setLinearVelocity(btVector3(0,0,0));
+	m_data->m_loadBody->setAngularVelocity(btVector3(0,0,0));
+
+}
+
+btRigidBody* ForkLiftPhysicsSetup::localCreateRigidBody(btScalar mass, const btTransform& startTransform, btCollisionShape* shape)
+{
+	btAssert((!shape || shape->getShapeType() != INVALID_SHAPE_PROXYTYPE));
+
+	//rigidbody is dynamic if and only if mass is non zero, otherwise static
+	bool isDynamic = (mass != 0.f);
+
+	btVector3 localInertia(0,0,0);
+	if (isDynamic)
+		shape->calculateLocalInertia(mass,localInertia);
+
+	//using motionstate is recommended, it provides interpolation capabilities, and only synchronizes 'active' objects
+
+//#define USE_MOTIONSTATE 1
+#ifdef USE_MOTIONSTATE
+	btDefaultMotionState* myMotionState = new btDefaultMotionState(startTransform);
+
+	btRigidBody::btRigidBodyConstructionInfo cInfo(mass,myMotionState,shape,localInertia);
+
+	btRigidBody* body = new btRigidBody(cInfo);
+	body->setContactProcessingThreshold(BT_LARGE_FLOAT);//m_defaultContactProcessingThreshold);
+
+#else
+	btRigidBody* body = new btRigidBody(mass,0,shape,localInertia);
+	body->setWorldTransform(startTransform);
+#endif//
+
+	m_data->m_dynamicsWorld->addRigidBody(body);
+	return body;
+}
+
+void ForkLiftPhysicsSetup::exitPhysics()
+{
+}
+void ForkLiftPhysicsSetup::stepSimulation(float deltaTime)
+{
+	m_data->m_dynamicsWorld->stepSimulation(deltaTime);
+}
+void    ForkLiftPhysicsSetup::debugDraw(int debugDrawFlags)
+{
+}
+bool ForkLiftPhysicsSetup::pickBody(const btVector3& rayFromWorld, const btVector3& rayToWorld)
+{
+	return false;
+}
+bool ForkLiftPhysicsSetup::movePickedBody(const btVector3& rayFromWorld, const btVector3& rayToWorld)
+{
+	return false;
+}
+void ForkLiftPhysicsSetup::removePickingConstraint()
+{
+}
+void ForkLiftPhysicsSetup::syncPhysicsToGraphics(GraphicsPhysicsBridge& gfxBridge)
+{
+	gfxBridge.syncPhysicsToGraphics(m_data->m_dynamicsWorld);
+	//sync wheels
+
+	for (int i=0;i<m_data->m_vehicle->getNumWheels();i++)
+	{
+		//synchronize the wheels with the (interpolated) chassis worldtransform
+		m_data->m_vehicle->updateWheelTransform(i,true);
+
+		CommonRenderInterface* renderer = gfxBridge.getRenderInterface();
+		if (renderer)
+		{
+			btTransform tr = m_data->m_vehicle->getWheelInfo(i).m_worldTransform;
+			btVector3 pos=tr.getOrigin();
+			btQuaternion orn = tr.getRotation();
+			renderer->writeSingleInstanceTransformToCPU(pos,orn,m_data->m_wheelInstances[i]);
+		}
+	}
+
+}
+
+void ForkLiftPhysicsSetup::renderScene(GraphicsPhysicsBridge& gfxBridge)
+{
+	gfxBridge.drawText3D("hi!",0,10,10,2);
+}
+
+void ForkLiftPhysicsSetup::lockLiftHinge()
+{
+}
+
+void ForkLiftPhysicsSetup::lockForkSlider()
+{
+}
diff --git a/Demos/ForkLiftDemo/ForkLiftPhysicsSetup.h b/Demos/ForkLiftDemo/ForkLiftPhysicsSetup.h
new file mode 100644
index 000000000..89e932668
--- /dev/null
+++ b/Demos/ForkLiftDemo/ForkLiftPhysicsSetup.h
@@ -0,0 +1,50 @@
+#ifndef FORK_LIFT_PHYSICS_SETUP_H
+#define FORK_LIFT_PHYSICS_SETUP_H
+
+class btRigidBody;
+class btCollisionShape;
+class btBroadphaseInterface;
+class btConstraintSolver;
+class btCollisionDispatcher;
+class btDefaultCollisionConfiguration;
+class btDiscreteDynamicsWorld;
+class btTransform;
+class btVector3;
+class btBoxShape;
+
+#include "LinearMath/btVector3.h"
+#include "LinearMath/btAlignedObjectArray.h"
+#include "Bullet3AppSupport/CommonRigidBodySetup.h"
+
+class ForkLiftPhysicsSetup : public CommonPhysicsSetup
+{
+
+protected:
+
+	struct ForkLiftInternalData* m_data;
+
+public:
+
+	ForkLiftPhysicsSetup();
+	virtual ~ForkLiftPhysicsSetup();
+	
+	virtual void initPhysics(GraphicsPhysicsBridge& gfxBridge);
+	
+	
+	virtual void exitPhysics();
+	virtual void stepSimulation(float deltaTime);
+	virtual void    debugDraw(int debugDrawFlags);
+	virtual bool pickBody(const btVector3& rayFromWorld, const btVector3& rayToWorld);
+	virtual bool movePickedBody(const btVector3& rayFromWorld, const btVector3& rayToWorld);
+	virtual void removePickingConstraint();
+	virtual void syncPhysicsToGraphics(GraphicsPhysicsBridge& gfxBridge);
+	virtual void renderScene(GraphicsPhysicsBridge& gfxBridge);
+
+	void resetForklift();
+	void lockLiftHinge();
+	void lockForkSlider();
+	class btRigidBody* localCreateRigidBody(btScalar mass, const btTransform& startTrans, btCollisionShape* shape);
+
+};
+
+#endif //FORK_LIFT_PHYSICS_SETUP_H
diff --git a/Demos/GyroscopicDemo/GyroscopicDemo.cpp b/Demos/GyroscopicDemo/GyroscopicDemo.cpp
index 31b399686..cc1a926c5 100644
--- a/Demos/GyroscopicDemo/GyroscopicDemo.cpp
+++ b/Demos/GyroscopicDemo/GyroscopicDemo.cpp
@@ -107,7 +107,7 @@ void	GyroscopicDemo::initPhysics()
 		m_dynamicsWorld->addRigidBody(body);
 		if (gyro[i])
 		{
-			body->setFlags(BT_ENABLE_GYROPSCOPIC_FORCE);
+			body->setFlags(BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY);
 		} else
 		{
 			body->setFlags(0);
diff --git a/Demos/GyroscopicDemo/GyroscopicSetup.cpp b/Demos/GyroscopicDemo/GyroscopicSetup.cpp
index c443bc2d5..3b3b497dd 100644
--- a/Demos/GyroscopicDemo/GyroscopicSetup.cpp
+++ b/Demos/GyroscopicDemo/GyroscopicSetup.cpp
@@ -1,19 +1,17 @@
 #include "GyroscopicSetup.h"
 
-static int gyroflags[5] = {
+static int gyroflags[4] = {
     0,//none, no gyroscopic term
     BT_ENABLE_GYROSCOPIC_FORCE_EXPLICIT,
-    BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_EWERT,
-    BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_CATTO,
-    BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_COOPER,
+    BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_WORLD,
+    BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY
 };
 
-static const char* gyroNames[5] = {
+static const char* gyroNames[4] = {
     "No Coriolis",
     "Explicit",
-    "Ewert",
-    "Catto",
-    "Cooper",
+    "Implicit (World)",
+	"Implicit (Body)"
 };
 
 
@@ -25,16 +23,15 @@ void GyroscopicSetup::initPhysics(GraphicsPhysicsBridge& gfxBridge)
 	gfxBridge.createPhysicsDebugDrawer(m_dynamicsWorld);
 
 	
-	btVector3 positions[5] = {
+	btVector3 positions[4] = {
 		btVector3( -10, 8,4),
 		btVector3( -5, 8,4),
 		btVector3( 0, 8,4),
 		btVector3( 5, 8,4),
-		btVector3( 10, 8,4),
 	};
 
 
-	for (int i = 0; i<5; i++)
+	for (int i = 0; i<4; i++)
 	{
 		btCylinderShapeZ* pin = new btCylinderShapeZ(btVector3(0.1,0.1, 0.2));
 		btBoxShape* box = new btBoxShape(btVector3(1,0.1,0.1));
diff --git a/Demos3/AllBullet2Demos/BulletDemoEntries.h b/Demos3/AllBullet2Demos/BulletDemoEntries.h
index 581c60d42..c7198ae55 100644
--- a/Demos3/AllBullet2Demos/BulletDemoEntries.h
+++ b/Demos3/AllBullet2Demos/BulletDemoEntries.h
@@ -16,6 +16,7 @@
 #include "../bullet2/RagdollDemo/RagdollDemo.h"
 #include "../bullet2/LuaDemo/LuaPhysicsSetup.h"
 #include "../bullet2/ChainDemo/ChainDemo.h"
+#include "../../Demos/ForkLiftDemo/ForkLiftPhysicsSetup.h"
 #include "../../Demos/CcdPhysicsDemo/CcdPhysicsSetup.h"
 #include "../../Demos/GyroscopicDemo/GyroscopicSetup.h"
 #include "../bullet2/ConstraintDemo/ConstraintPhysicsSetup.h"
@@ -57,6 +58,7 @@ MYCREATEFUNC2(LuaDemoCreateFunc,LuaPhysicsSetup);
 MYCREATEFUNC(Serialize);
 MYCREATEFUNC(CcdPhysics);
 MYCREATEFUNC(Gyroscopic);
+MYCREATEFUNC(ForkLiftPhysics);
 MYCREATEFUNC(KinematicObject);
 MYCREATEFUNC(ConstraintPhysics);
 MYCREATEFUNC(Dof6Spring2);
@@ -96,6 +98,7 @@ static BulletDemoEntry allDemos[]=
 	{0,"API Demos", 0},
 	{1,"Raytracer",RaytracerPhysicsCreateFunc},
 	{1,"BasicDemo",BasicDemo::MyCreateFunc},
+	{1,"ForkLift",ForkLiftPhysicsCreateFunc},
 	{ 1, "CcdDemo", CcdPhysicsCreateFunc },
 	{ 1, "Gyroscopic", GyroscopicCreateFunc },
 	{ 1, "Kinematic", KinematicObjectCreateFunc },
diff --git a/Demos3/AllBullet2Demos/CMakeLists.txt b/Demos3/AllBullet2Demos/CMakeLists.txt
index a846a092e..5e3a7c5b9 100644
--- a/Demos3/AllBullet2Demos/CMakeLists.txt
+++ b/Demos3/AllBullet2Demos/CMakeLists.txt
@@ -18,6 +18,8 @@ SET(App_AllBullet2Demos_SRCS
 	../../Demos/Raytracer/RaytracerSetup.h
 	../../Demos/GyroscopicDemo/GyroscopicSetup.cpp
 	../../Demos/GyroscopicDemo/GyroscopicSetup.h
+	../../Demos/ForkLiftDemo/ForkLiftPhysicsSetup.cpp
+	../../Demos/ForkLiftDemo/ForkLiftPhysicsSetup.h
 	../../Demos/SerializeDemo/SerializeSetup.cpp
         ../../Extras/Serialize/BulletFileLoader/bChunk.cpp
         ../../Extras/Serialize/BulletFileLoader/bDNA.cpp
diff --git a/Demos3/AllBullet2Demos/premake4.lua b/Demos3/AllBullet2Demos/premake4.lua
index 17e17f8ac..4626235b5 100644
--- a/Demos3/AllBullet2Demos/premake4.lua
+++ b/Demos3/AllBullet2Demos/premake4.lua
@@ -53,6 +53,8 @@
 		"../FiniteElementMethod/FiniteElementDemo.cpp",
 		"../../Demos/BasicDemo/BasicDemoPhysicsSetup.cpp",
 		"../../Demos/BasicDemo/BasicDemoPhysicsSetup.h",
+		"../../Demos/ForkLiftDemo/ForkLiftPhysicsSetup.cpp",
+		"../../Demos/ForkLiftDemo/ForkLiftPhysicsSetup.h",
 		"../../Demos/CcdPhysicsDemo/CcdPhysicsSetup.cpp",
 		"../../Demos/CcdPhysicsDemo/CcdPhysicsSetup.h",
 		"../../Demos/Raytracer/RaytracerSetup.cpp",
diff --git a/btgui/Bullet3AppSupport/Bullet2RigidBodyDemo.cpp b/btgui/Bullet3AppSupport/Bullet2RigidBodyDemo.cpp
index 13dcc7817..33d25ed03 100644
--- a/btgui/Bullet3AppSupport/Bullet2RigidBodyDemo.cpp
+++ b/btgui/Bullet3AppSupport/Bullet2RigidBodyDemo.cpp
@@ -30,6 +30,12 @@ struct MyGraphicsPhysicsBridge : public GraphicsPhysicsBridge
 		:m_glApp(glApp), m_debugDraw(0), m_curColor(0)
 	{
 	}
+
+	virtual struct CommonRenderInterface* getRenderInterface()
+	{
+		return m_glApp->m_renderer;
+	}
+
 	virtual void createRigidBodyGraphicsObject(btRigidBody* body, const btVector3& color)
 	{
 	    createCollisionObjectGraphicsObject(body,color);
@@ -319,9 +325,10 @@ void Bullet2RigidBodyDemo::renderScene()
 
 	MyGraphicsPhysicsBridge glBridge(m_glApp);
 	m_physicsSetup->syncPhysicsToGraphics(glBridge);
-
 	m_glApp->m_renderer->renderScene();
 
+	m_physicsSetup->renderScene(glBridge);
+
 }
 
 void	Bullet2RigidBodyDemo::physicsDebugDraw(int debugDrawFlags)
diff --git a/btgui/Bullet3AppSupport/CommonPhysicsSetup.h b/btgui/Bullet3AppSupport/CommonPhysicsSetup.h
index b1146e2a4..616e352de 100644
--- a/btgui/Bullet3AppSupport/CommonPhysicsSetup.h
+++ b/btgui/Bullet3AppSupport/CommonPhysicsSetup.h
@@ -48,6 +48,10 @@ struct GraphicsPhysicsBridge
 		return 0;
 	}
 
+	virtual struct CommonRenderInterface* getRenderInterface()
+	{
+		return 0;
+	}
 	virtual void setUpAxis(int axis)
 	{
 	}
@@ -77,6 +81,7 @@ public:
 
     virtual void    debugDraw(int debugDrawFlags)=0;
 
+	virtual void renderScene(GraphicsPhysicsBridge& gfxBridge){};
 	
 	virtual bool pickBody(const btVector3& rayFromWorld, const btVector3& rayToWorld) = 0;
 	virtual bool movePickedBody(const btVector3& rayFromWorld, const btVector3& rayToWorld)=0;
diff --git a/btgui/OpenGLWindow/SimpleOpenGL3App.cpp b/btgui/OpenGLWindow/SimpleOpenGL3App.cpp
index 814e65196..e8df27f5e 100644
--- a/btgui/OpenGLWindow/SimpleOpenGL3App.cpp
+++ b/btgui/OpenGLWindow/SimpleOpenGL3App.cpp
@@ -255,7 +255,7 @@ void SimpleOpenGL3App::drawText3D( const char* txt, float worldPosX, float world
 		//float extraSpacing = 0.;
 
 		float startX = posX;
-		float startY = posY-g_DefaultLargeFont->m_CharHeight;
+		float startY = posY-g_DefaultLargeFont->m_CharHeight*size1;
 		
 
 		while (txt[pos])
@@ -263,7 +263,7 @@ void SimpleOpenGL3App::drawText3D( const char* txt, float worldPosX, float world
 			int c = txt[pos];
 			//r.h = g_DefaultNormalFont->m_CharHeight;
 			//r.w = g_DefaultNormalFont->m_CharWidth[c]+extraSpacing;
-			float endX = startX+g_DefaultLargeFont->m_CharWidth[c];
+			float endX = startX+g_DefaultLargeFont->m_CharWidth[c]*size1;
 			float endY = posY;
 
 
diff --git a/src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp b/src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp
index b80b6632b..8da572bf7 100644
--- a/src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp
+++ b/src/BulletDynamics/ConstraintSolver/btSequentialImpulseConstraintSolver.cpp
@@ -1271,22 +1271,17 @@ btScalar btSequentialImpulseConstraintSolver::solveGroupCacheFriendlySetup(btCol
 			btVector3 gyroForce (0,0,0);
 			if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_EXPLICIT)
 			{
-				gyroForce = body->computeGyroscopicForce(infoGlobal.m_maxGyroscopicForce);
+				gyroForce = body->computeGyroscopicForceExplicit(infoGlobal.m_maxGyroscopicForce);
 				solverBody.m_externalTorqueImpulse -= gyroForce*body->getInvInertiaTensorWorld()*infoGlobal.m_timeStep;
 			}
-			if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_EWERT)
+			if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_WORLD)
 			{
-				gyroForce = body->computeGyroscopicImpulseImplicit_Ewert(infoGlobal.m_timeStep);
+				gyroForce = body->computeGyroscopicImpulseImplicit_World(infoGlobal.m_timeStep);
 				solverBody.m_externalTorqueImpulse += gyroForce;
 			}
-			if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_COOPER)
+			if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY)
 			{
-				gyroForce = body->computeGyroscopicImpulseImplicit_Cooper(infoGlobal.m_timeStep);
-				solverBody.m_externalTorqueImpulse += gyroForce;
-			}
-			if (body->getFlags()&BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_CATTO)
-			{
-				gyroForce = body->computeGyroscopicImpulseImplicit_Catto(infoGlobal.m_timeStep);
+				gyroForce = body->computeGyroscopicImpulseImplicit_Body(infoGlobal.m_timeStep);
 				solverBody.m_externalTorqueImpulse += gyroForce;
 
 			}
diff --git a/src/BulletDynamics/Dynamics/btRigidBody.cpp b/src/BulletDynamics/Dynamics/btRigidBody.cpp
index 5df324fe7..8bc3c1ca5 100644
--- a/src/BulletDynamics/Dynamics/btRigidBody.cpp
+++ b/src/BulletDynamics/Dynamics/btRigidBody.cpp
@@ -87,7 +87,7 @@ void	btRigidBody::setupRigidBody(const btRigidBody::btRigidBodyConstructionInfo&
 	setMassProps(constructionInfo.m_mass, constructionInfo.m_localInertia);
 	updateInertiaTensor();
 
-	m_rigidbodyFlags = BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_EWERT;
+	m_rigidbodyFlags = BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY;
 
 
 	m_deltaLinearVelocity.setZero();
@@ -289,7 +289,7 @@ inline btMatrix3x3 evalEulerEqnDeriv(const btVector3& w1, const btVector3& w0, c
 	return dfw1;
 }
 
-btVector3 btRigidBody::computeGyroscopicForce(btScalar maxGyroscopicForce) const
+btVector3 btRigidBody::computeGyroscopicForceExplicit(btScalar maxGyroscopicForce) const
 {
 	btVector3 inertiaLocal = getLocalInertia();
 	btMatrix3x3 inertiaTensorWorld = getWorldTransform().getBasis().scaled(inertiaLocal) * getWorldTransform().getBasis().transpose();
@@ -311,7 +311,7 @@ void btSetCrossMatrixMinus(btMatrix3x3& res, const btVector3& a)
 		+a_1, -a_0, 0);
 }
 
-btVector3 btRigidBody::computeGyroscopicImpulseImplicit_Catto(btScalar step) const
+btVector3 btRigidBody::computeGyroscopicImpulseImplicit_Body(btScalar step) const
 {	
 	btVector3 idl = getLocalInertia();
 	btVector3 omega1 = getAngularVelocity();
@@ -338,8 +338,9 @@ btVector3 btRigidBody::computeGyroscopicImpulseImplicit_Catto(btScalar step) con
 	// Jacobian
 	btMatrix3x3 J = Ib +  (skew0*Ib - skew1)*step;
 	
-	btMatrix3x3 Jinv = J.inverse();
-	btVector3 omega_div = Jinv*f;
+//	btMatrix3x3 Jinv = J.inverse();
+//	btVector3 omega_div = Jinv*f;
+	btVector3 omega_div = J.solve33(f);
 	
 	// Single Newton-Raphson update
 	omegab = omegab - omega_div;//Solve33(J, f);
@@ -351,94 +352,7 @@ btVector3 btRigidBody::computeGyroscopicImpulseImplicit_Catto(btScalar step) con
 
 
 
-btVector3 btRigidBody::computeGyroscopicImpulseImplicit_Cooper(btScalar step) const
-{
-#if 0
-	dReal h = callContext->m_stepperCallContext->m_stepSize; // Step size
-	dVector3 L; // Compute angular momentum
-	dMultiply0_331(L, I, b->avel);
-#endif
-
-	btVector3 inertiaLocal = getLocalInertia();
-	btMatrix3x3 inertiaTensorWorld = getWorldTransform().getBasis().scaled(inertiaLocal) * getWorldTransform().getBasis().transpose();
-	btVector3 L = inertiaTensorWorld*getAngularVelocity();
-
-	btMatrix3x3 Itild(0, 0, 0, 0, 0, 0, 0, 0, 0);
-
-#if 0
-	for (int ii = 0; ii<12; ++ii) {
-		Itild[ii] = Itild[ii] * h + I[ii];
-	}
-#endif
-
-	btSetCrossMatrixMinus(Itild, L*step);
-	Itild += inertiaTensorWorld;
-	
-
-#if 0
-// Compute a new effective 'inertia tensor'
-// for the implicit step: the cross-product 
-// matrix of the angular momentum plus the
-// old tensor scaled by the timestep.  
-// Itild may not be symmetric pos-definite, 
-// but we can still use it to compute implicit
-// gyroscopic torques.
-dMatrix3 Itild = { 0 };
-dSetCrossMatrixMinus(Itild, L, 4);
-for (int ii = 0; ii<12; ++ii) {
-	Itild[ii] = Itild[ii] * h + I[ii];
-}
-#endif
-
-	L *= step;
-	//Itild may not be symmetric pos-definite
-	btMatrix3x3 itInv = Itild.inverse();
-	Itild =  inertiaTensorWorld * itInv;
-	btMatrix3x3 ident(1,0,0,0,1,0,0,0,1);
-	Itild -= ident;
-
-	
-
-
-#if 0
-// Scale momentum by inverse time to get 
-// a sort of "torque"
-dScaleVector3(L, dRecip(h));
-// Invert the pseudo-tensor
-dMatrix3 itInv;
-// This is a closed-form inversion.
-// It's probably not numerically stable
-// when dealing with small masses with
-// a large asymmetry.
-// An LU decomposition might be better.
-if (dInvertMatrix3(itInv, Itild) != 0) {
-	// "Divide" the original tensor
-	// by the pseudo-tensor (on the right)
-	dMultiply0_333(Itild, I, itInv);
-	// Subtract an identity matrix
-	Itild[0] -= 1; Itild[5] -= 1; Itild[10] -= 1;
-
-	// This new inertia matrix rotates the 
-	// momentum to get a new set of torques
-	// that will work correctly when applied
-	// to the old inertia matrix as explicit
-	// torques with a semi-implicit update
-	// step.
-	dVector3 tau0;
-	dMultiply0_331(tau0, Itild, L);
-
-	// Add the gyro torques to the torque 
-	// accumulator
-	for (int ii = 0; ii<3; ++ii) {
-		b->tacc[ii] += tau0[ii];
-	}
-#endif
-	btVector3 tau0 = Itild * L;
-//	printf("tau0 = %f,%f,%f\n",tau0.x(),tau0.y(),tau0.z());
-	return tau0;
-}
-
-btVector3 btRigidBody::computeGyroscopicImpulseImplicit_Ewert(btScalar step) const
+btVector3 btRigidBody::computeGyroscopicImpulseImplicit_World(btScalar step) const
 {
 	// use full newton-euler equations.  common practice to drop the wxIw term. want it for better tumbling behavior.
 	// calculate using implicit euler step so it's stable.
@@ -462,10 +376,10 @@ btVector3 btRigidBody::computeGyroscopicImpulseImplicit_Ewert(btScalar step) con
 		const btVector3 fw = evalEulerEqn(w1, w0, btVector3(0, 0, 0), step, I);
 		const btMatrix3x3 dfw = evalEulerEqnDeriv(w1, w0, step, I);
 
-		const btMatrix3x3 dfw_inv = dfw.inverse();
 		btVector3 dw;
-
-		dw = dfw_inv*fw;
+		dw = dfw.solve33(fw);
+		//const btMatrix3x3 dfw_inv = dfw.inverse();
+		//dw = dfw_inv*fw;
 
 		w1 -= dw;
 	}
diff --git a/src/BulletDynamics/Dynamics/btRigidBody.h b/src/BulletDynamics/Dynamics/btRigidBody.h
index ae6c8fd4a..1d177db80 100644
--- a/src/BulletDynamics/Dynamics/btRigidBody.h
+++ b/src/BulletDynamics/Dynamics/btRigidBody.h
@@ -42,11 +42,12 @@ enum	btRigidBodyFlags
 {
 	BT_DISABLE_WORLD_GRAVITY = 1,
 	///BT_ENABLE_GYROPSCOPIC_FORCE flags is enabled by default in Bullet 2.83 and onwards.
+	///and it BT_ENABLE_GYROPSCOPIC_FORCE becomes equivalent to BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY
 	///See Demos/GyroscopicDemo and computeGyroscopicImpulseImplicit
 	BT_ENABLE_GYROSCOPIC_FORCE_EXPLICIT = 2,
-	BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_COOPER=4,
-	BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_EWERT=8,
-	BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_CATTO=16,
+	BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_WORLD=4,
+	BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY=8,
+	BT_ENABLE_GYROPSCOPIC_FORCE = BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY,
 };
 
 
@@ -534,11 +535,14 @@ public:
 
 	
 
-	btVector3 computeGyroscopicImpulseImplicit_Ewert(btScalar dt) const;
-	btVector3 computeGyroscopicImpulseImplicit_Cooper(btScalar step) const;
-	btVector3 computeGyroscopicImpulseImplicit_Catto(btScalar step) const;
+	///perform implicit force computation in world space
+	btVector3 computeGyroscopicImpulseImplicit_World(btScalar dt) const;
+	
+	///perform implicit force computation in body space (inertial frame)
+	btVector3 computeGyroscopicImpulseImplicit_Body(btScalar step) const;
 
-	btVector3 computeGyroscopicForce(btScalar maxGyroscopicForce) const;//explicit version is best avoided, it gains energy
+	///explicit version is best avoided, it gains energy
+	btVector3 computeGyroscopicForceExplicit(btScalar maxGyroscopicForce) const;
 	btVector3 getLocalInertia() const;
 
 	///////////////////////////////////////////////
diff --git a/src/LinearMath/btMatrix3x3.h b/src/LinearMath/btMatrix3x3.h
index 14fe704f8..41dea6948 100644
--- a/src/LinearMath/btMatrix3x3.h
+++ b/src/LinearMath/btMatrix3x3.h
@@ -610,6 +610,27 @@ public:
 	/**@brief Return the inverse of the matrix */
 	btMatrix3x3 inverse() const; 
 
+	/// Solve A * x = b, where b is a column vector. This is more efficient
+	/// than computing the inverse in one-shot cases.
+	///Solve33 is from Box2d, thanks to Erin Catto,
+	btVector3 solve33(const btVector3& b) const
+	{
+		btVector3 col1 = getColumn(0);
+		btVector3 col2 = getColumn(1);
+		btVector3 col3 = getColumn(2);
+		
+		btScalar det = btDot(col1, btCross(col2, col3));
+		if (btFabs(det)>SIMD_EPSILON)
+		{
+			det = 1.0f / det;
+		}
+		btVector3 x;
+		x[0] = det * btDot(b, btCross(col2, col3));
+		x[1] = det * btDot(col1, btCross(b, col3));
+		x[2] = det * btDot(col1, btCross(col2, b));
+		return x;
+	}
+
 	btMatrix3x3 transposeTimes(const btMatrix3x3& m) const;
 	btMatrix3x3 timesTranspose(const btMatrix3x3& m) const;