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diff --git a/examples/ReducedDeformableDemo/FreeFall.cpp b/examples/ReducedDeformableDemo/FreeFall.cpp
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+/*
+ Bullet Continuous Collision Detection and Physics Library
+ Copyright (c) 2019 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 "FreeFall.h"
+///btBulletDynamicsCommon.h is the main Bullet include file, contains most common include files.
+#include "btBulletDynamicsCommon.h"
+#include "BulletSoftBody/btDeformableMultiBodyDynamicsWorld.h"
+#include "BulletSoftBody/BulletReducedDeformableBody/btReducedDeformableBody.h"
+#include "BulletSoftBody/BulletReducedDeformableBody/btReducedDeformableBodyHelpers.h"
+#include "BulletSoftBody/BulletReducedDeformableBody/btReducedDeformableBodySolver.h"
+#include "BulletSoftBody/btSoftBodyRigidBodyCollisionConfiguration.h"
+#include "BulletDynamics/Featherstone/btMultiBodyConstraintSolver.h"
+#include "../CommonInterfaces/CommonParameterInterface.h"
+#include <stdio.h>  //printf debugging
+
+#include "../CommonInterfaces/CommonDeformableBodyBase.h"
+#include "../Utils/b3ResourcePath.h"
+
+///The BasicTest shows the contact between volumetric deformable objects and rigid objects.
+// static btScalar E = 50;
+// static btScalar nu = 0.3;
+static btScalar damping_alpha = 0.0;
+static btScalar damping_beta = 0.0001;
+static btScalar COLLIDING_VELOCITY = 0;
+static int num_modes = 40;
+
+class FreeFall : public CommonDeformableBodyBase
+{
+public:
+    FreeFall(struct GUIHelperInterface* helper)
+        : CommonDeformableBodyBase(helper)
+    {
+    }
+    virtual ~FreeFall()
+    {
+    }
+    void initPhysics();
+
+    void exitPhysics();
+
+    // TODO: disable pick force, non-interactive for now.
+    bool pickBody(const btVector3& rayFromWorld, const btVector3& rayToWorld) {
+        return false;
+    } 
+
+    void resetCamera()
+    {
+        float dist = 8;
+        float pitch = -10;
+        float yaw = 90;
+        float targetPos[3] = {0, 2, 0};
+        // float dist = 10;
+        // float pitch = -30;
+        // float yaw = 125;
+        // float targetPos[3] = {0, 2, 0};
+        m_guiHelper->resetCamera(dist, yaw, pitch, targetPos[0], targetPos[1], targetPos[2]);
+    }
+    
+    void Ctor_RbUpStack(const btVector3& origin)
+    {
+        float mass = 10;
+        btCollisionShape* shape = new btBoxShape(btVector3(0.5, 0.5, 0.5));
+        // btCollisionShape* shape = new btBoxShape(btVector3(1, 1, 1));
+        btTransform startTransform;
+        startTransform.setIdentity();
+        // startTransform.setOrigin(btVector3(0, 12, 0));
+        // btRigidBody* rb0 = createRigidBody(mass, startTransform, shape);
+        // rb0->setLinearVelocity(btVector3(0, 0, 0));
+
+        startTransform.setOrigin(origin);
+        // startTransform.setRotation(btQuaternion(btVector3(1, 0, 1), SIMD_PI / 4.0));
+        btRigidBody* rb1 = createRigidBody(mass, startTransform, shape);
+        rb1->setActivationState(DISABLE_DEACTIVATION);
+        rb1->setLinearVelocity(btVector3(0, 0, 0));
+    }
+
+    void createReducedDeformableObject(const btVector3& origin, const btQuaternion& rotation)
+    {   
+        std::string file_path("../../../data/reduced_cube/");
+        std::string vtk_file("cube_mesh.vtk");
+        btReducedDeformableBody* rsb = btReducedDeformableBodyHelpers::createReducedDeformableObject(
+                                            getDeformableDynamicsWorld()->getWorldInfo(),
+                                            file_path,
+                                            vtk_file,
+                                            num_modes,
+                                            false);
+
+        getDeformableDynamicsWorld()->addSoftBody(rsb);
+        rsb->getCollisionShape()->setMargin(0.01);
+        // rsb->scale(btVector3(1, 1, 0.5));
+
+        rsb->setTotalMass(10);
+
+        btTransform init_transform;
+        init_transform.setIdentity();
+        init_transform.setOrigin(origin);
+        init_transform.setRotation(rotation);
+        rsb->transformTo(init_transform);
+
+        rsb->setStiffnessScale(25);
+        rsb->setDamping(damping_alpha, damping_beta);
+        // rsb->scale(btVector3(0.5, 0.5, 0.5));
+
+        rsb->m_cfg.kKHR = 1; // collision hardness with kinematic objects
+        rsb->m_cfg.kCHR = 1; // collision hardness with rigid body
+        rsb->m_cfg.kDF = 0;
+        rsb->m_cfg.collisions = btSoftBody::fCollision::SDF_RD;
+        rsb->m_cfg.collisions |= btSoftBody::fCollision::SDF_RDN;
+        rsb->m_sleepingThreshold = 0;
+        btSoftBodyHelpers::generateBoundaryFaces(rsb);
+    }
+    
+    void stepSimulation(float deltaTime)
+    {
+      float internalTimeStep = 1. / 60.f;
+      m_dynamicsWorld->stepSimulation(deltaTime, 1, internalTimeStep);
+    }
+    
+    virtual void renderScene()
+    {
+        CommonDeformableBodyBase::renderScene();
+        btDeformableMultiBodyDynamicsWorld* deformableWorld = getDeformableDynamicsWorld();
+        // int flag = 0;
+        
+        for (int i = 0; i < deformableWorld->getSoftBodyArray().size(); i++)
+        {
+            btReducedDeformableBody* rsb = static_cast<btReducedDeformableBody*>(deformableWorld->getSoftBodyArray()[i]);
+            {
+                btSoftBodyHelpers::DrawFrame(rsb, deformableWorld->getDebugDrawer());
+                // btSoftBodyHelpers::Draw(rsb, deformableWorld->getDebugDrawer(), flag);
+                btSoftBodyHelpers::Draw(rsb, deformableWorld->getDebugDrawer(), deformableWorld->getDrawFlags()); 
+
+                // for (int p = 0; p < rsb->m_fixedNodes.size(); ++p)
+                // {
+                //     deformableWorld->getDebugDrawer()->drawSphere(rsb->m_nodes[rsb->m_fixedNodes[p]].m_x, 0.2, btVector3(1, 0, 0));
+                // }
+                // for (int p = 0; p < rsb->m_nodeRigidContacts.size(); ++p)
+                // {
+                //     deformableWorld->getDebugDrawer()->drawSphere(rsb->m_nodes[rsb->m_contactNodesList[p]].m_x, 0.2, btVector3(0, 1, 0));
+                // }
+
+                // deformableWorld->getDebugDrawer()->drawSphere(btVector3(0, 0, 0), 0.1, btVector3(1, 1, 1));
+                // deformableWorld->getDebugDrawer()->drawSphere(btVector3(0, 5, 0), 0.1, btVector3(1, 1, 1));
+                // deformableWorld->getDebugDrawer()->drawSphere(btVector3(0, 10, 0), 0.1, btVector3(1, 1, 1));
+            }
+        }
+    }
+};
+
+void FreeFall::initPhysics()
+{
+    m_guiHelper->setUpAxis(1);
+
+    ///collision configuration contains default setup for memory, collision setup
+    m_collisionConfiguration = new btSoftBodyRigidBodyCollisionConfiguration();
+
+    ///use the default collision dispatcher. For parallel processing you can use a diffent dispatcher (see Extras/BulletMultiThreaded)
+    m_dispatcher = new btCollisionDispatcher(m_collisionConfiguration);
+
+    m_broadphase = new btDbvtBroadphase();
+    btReducedDeformableBodySolver* reducedSoftBodySolver = new btReducedDeformableBodySolver();
+
+    btDeformableMultiBodyConstraintSolver* sol = new btDeformableMultiBodyConstraintSolver();
+    sol->setDeformableSolver(reducedSoftBodySolver);
+    m_solver = sol;
+
+    m_dynamicsWorld = new btDeformableMultiBodyDynamicsWorld(m_dispatcher, m_broadphase, sol, m_collisionConfiguration, reducedSoftBodySolver);
+    btVector3 gravity = btVector3(0, -9.8, 0);
+    m_dynamicsWorld->setGravity(gravity);
+    m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
+    // m_dynamicsWorld->getSolverInfo().m_solverMode |= SOLVER_RANDMIZE_ORDER;
+    
+    // 2 reduced deformable cubes
+    createReducedDeformableObject(btVector3(0, 4, -2), btQuaternion(0, 0, 0));
+    createReducedDeformableObject(btVector3(0, 4, 2), btQuaternion(0, 0, 0));
+   
+    // 2 rigid cubes
+    Ctor_RbUpStack(btVector3(0, 10, -2));
+    Ctor_RbUpStack(btVector3(0, 10, 2));
+    
+    // create a static rigid box as the ground
+    {
+        // btBoxShape* groundShape = createBoxShape(btVector3(btScalar(50), btScalar(50), btScalar(50)));
+        btBoxShape* groundShape = createBoxShape(btVector3(btScalar(10), btScalar(2), btScalar(10)));
+        m_collisionShapes.push_back(groundShape);
+
+        btTransform groundTransform;
+        groundTransform.setIdentity();
+        // groundTransform.setRotation(btQuaternion(btVector3(1, 0, 0), SIMD_PI / 6.0));
+        // groundTransform.setRotation(btQuaternion(btVector3(0, 0, 1), SIMD_PI / 6.0));
+        groundTransform.setOrigin(btVector3(0, -2, 0));
+        // groundTransform.setOrigin(btVector3(0, 0, 6));
+        // groundTransform.setOrigin(btVector3(0, -50, 0));
+        {
+            btScalar mass(0.);
+            createRigidBody(mass, groundTransform, groundShape, btVector4(0,0,0,0));
+        }
+    }
+
+    getDeformableDynamicsWorld()->setImplicit(false);
+    getDeformableDynamicsWorld()->setLineSearch(false);
+    getDeformableDynamicsWorld()->setUseProjection(false);
+    getDeformableDynamicsWorld()->getSolverInfo().m_deformable_erp = 0.2;
+    getDeformableDynamicsWorld()->getSolverInfo().m_deformable_cfm = 0.2;
+    getDeformableDynamicsWorld()->getSolverInfo().m_friction = 0.5;
+    getDeformableDynamicsWorld()->getSolverInfo().m_deformable_maxErrorReduction = btScalar(200);
+    getDeformableDynamicsWorld()->getSolverInfo().m_leastSquaresResidualThreshold = 1e-3;
+    getDeformableDynamicsWorld()->getSolverInfo().m_splitImpulse = false;
+    getDeformableDynamicsWorld()->getSolverInfo().m_numIterations = 100;
+
+    m_guiHelper->autogenerateGraphicsObjects(m_dynamicsWorld);
+    m_dynamicsWorld->setGravity(gravity);
+}
+
+void FreeFall::exitPhysics()
+{
+    //cleanup in the reverse order of creation/initialization
+    removePickingConstraint();
+    //remove the rigidbodies from the dynamics world and delete them
+    int i;
+    for (i = m_dynamicsWorld->getNumCollisionObjects() - 1; i >= 0; i--)
+    {
+        btCollisionObject* obj = m_dynamicsWorld->getCollisionObjectArray()[i];
+        btRigidBody* body = btRigidBody::upcast(obj);
+        if (body && body->getMotionState())
+        {
+            delete body->getMotionState();
+        }
+        m_dynamicsWorld->removeCollisionObject(obj);
+        delete obj;
+    }
+    // delete forces
+    for (int j = 0; j < m_forces.size(); j++)
+    {
+        btDeformableLagrangianForce* force = m_forces[j];
+        delete force;
+    }
+    m_forces.clear();
+    
+    //delete collision shapes
+    for (int j = 0; j < m_collisionShapes.size(); j++)
+    {
+        btCollisionShape* shape = m_collisionShapes[j];
+        delete shape;
+    }
+    m_collisionShapes.clear();
+
+    delete m_dynamicsWorld;
+
+    delete m_solver;
+
+    delete m_broadphase;
+
+    delete m_dispatcher;
+
+    delete m_collisionConfiguration;
+}
+
+
+
+class CommonExampleInterface* ReducedFreeFallCreateFunc(struct CommonExampleOptions& options)
+{
+    return new FreeFall(options.m_guiHelper);
+}
+
+