created new free fall example. WIP

examples/ExampleBrowser/CMakeLists.txt

@@ -392,6 +392,8 @@ SET(BulletExampleBrowser_SRCS
 	../ReducedDeformableDemo/BasicTest.h
 	../ReducedDeformableDemo/ModeVisualizer.cpp
 	../ReducedDeformableDemo/ModeVisualizer.h
+	../ReducedDeformableDemo/FreeFall.cpp
+	../ReducedDeformableDemo/FreeFall.h
   ../Constraints/TestHingeTorque.cpp
   ../Constraints/TestHingeTorque.h
   ../Constraints/ConstraintDemo.cpp

examples/ExampleBrowser/ExampleEntries.cpp

@@ -72,8 +72,9 @@
 #include "../RoboticsLearning/R2D2GraspExample.h"
 #include "../RoboticsLearning/KukaGraspExample.h"
 #include "../RoboticsLearning/GripperGraspExample.h"
-#include "../ReducedDeformableDemo/BasicTest.h"
 #include "../ReducedDeformableDemo/ModeVisualizer.h"
+#include "../ReducedDeformableDemo/BasicTest.h"
+#include "../ReducedDeformableDemo/FreeFall.h"
 #include "../InverseKinematics/InverseKinematicsExample.h"
 
 #ifdef B3_ENABLE_TINY_AUDIO
@@ -220,6 +221,7 @@ static ExampleEntry gDefaultExamples[] =
 		ExampleEntry(0, "Reduced Deformabe Body"),
 		ExampleEntry(1, "Mode Visualizer", "Visualizer the modes for reduced deformable objects", ReducedModeVisualizerCreateFunc),
 		ExampleEntry(1, "BasicRD", "Simple dynamics test for the reduced deformable objects", ReducedBasicTestCreateFunc),
+		ExampleEntry(1, "Reduced Free Fall", "Free fall ground contact test for the reduced deformable model", ReducedFreeFallCreateFunc),
 		// ExampleEntry(1, "Simple Reduced Deformable Test", "Simple dynamics test for the reduced deformable objects", ReducedBasicTestCreateFunc),
         
 #ifdef INCLUDE_CLOTH_DEMOS

examples/ReducedDeformableDemo/BasicTest.cpp

@@ -169,7 +169,7 @@ void BasicTest::initPhysics()
     m_dynamicsWorld->setGravity(gravity);
     m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
 
-    // create volumetric soft body
+    // create volumetric reduced deformable body
     {   
         std::string filepath("../../../examples/SoftDemo/");
         std::string filename = filepath + "mesh.vtk";
@@ -180,11 +180,17 @@ void BasicTest::initPhysics()
 
         getDeformableDynamicsWorld()->addSoftBody(rsb);
         rsb->getCollisionShape()->setMargin(0.1);
-        // rsb->scale(btVector3(1, 1, 1));
-        rsb->translate(btVector3(0, 4, 0));  //TODO: add back translate and scale
+        // rsb->scale(btVector3(1, 1, 1));  //TODO: add back scale
+        rsb->translate(btVector3(0, 4, 0));
         // rsb->setTotalMass(0.5);
         rsb->setStiffnessScale(0.5);
-        rsb->setFixedNodes();
+        
+        // set fixed nodes
+        rsb->setFixedNodes(0);
+        rsb->setFixedNodes(1);
+        rsb->setFixedNodes(2);
+        rsb->setFixedNodes(3);
+        
         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;

examples/ReducedDeformableDemo/FreeFall.cpp

@@ -0,0 +1,285 @@
+/*
+ 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/BulletReducedSoftBody/btReducedSoftBody.h"
+#include "BulletSoftBody/BulletReducedSoftBody/btReducedSoftBodyHelpers.h"
+#include "BulletSoftBody/BulletReducedSoftBody/btReducedSoftBodySolver.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 = 0.01;
+static btScalar COLLIDING_VELOCITY = 0;
+static int start_mode = 6;
+static int num_modes = 4;
+
+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 = 10;
+        float pitch = -30;
+        float yaw = 60;
+        float targetPos[3] = {0, 6, 0};
+        m_guiHelper->resetCamera(dist, yaw, pitch, targetPos[0], targetPos[1], targetPos[2]);
+    }
+    
+    void Ctor_RbUpStack()
+    {
+        float mass = 0.5;
+        btCollisionShape* shape = new btBoxShape(btVector3(2, 2, 2));
+        btTransform startTransform;
+        startTransform.setIdentity();
+        startTransform.setOrigin(btVector3(0,-2,0));
+        btRigidBody* rb = createRigidBody(mass, startTransform, shape);
+        rb->setLinearVelocity(btVector3(0,+COLLIDING_VELOCITY, 0));
+    }
+    
+    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++)
+        {
+            btReducedSoftBody* rsb = static_cast<btReducedSoftBody*>(deformableWorld->getSoftBodyArray()[i]);
+            {
+                btSoftBodyHelpers::DrawFrame(rsb, deformableWorld->getDebugDrawer());
+                // btSoftBodyHelpers::Draw(rsb, deformableWorld->getDebugDrawer(), flag);
+                btSoftBodyHelpers::Draw(rsb, deformableWorld->getDebugDrawer(), deformableWorld->getDrawFlags()); 
+
+                btVector3 origin = rsb->getRigidTransform().getOrigin();
+                btVector3 line_x = rsb->getRigidTransform().getBasis() * 2 * btVector3(1, 0, 0) + origin;
+                btVector3 line_y = rsb->getRigidTransform().getBasis() * 2 * btVector3(0, 1, 0) + origin;
+                btVector3 line_z = rsb->getRigidTransform().getBasis() * 2 * btVector3(0, 0, 1) + origin;
+
+                deformableWorld->getDebugDrawer()->drawLine(origin, line_x, btVector3(1, 0, 0));
+                deformableWorld->getDebugDrawer()->drawLine(origin, line_y, btVector3(0, 1, 0));
+                deformableWorld->getDebugDrawer()->drawLine(origin, line_z, btVector3(0, 0, 1));
+
+                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));
+                    // std::cout << rsb->m_nodes[rsb->m_fixedNodes[p]].m_x[0] << "\t" << rsb->m_nodes[rsb->m_fixedNodes[p]].m_x[1] << "\t" << rsb->m_nodes[rsb->m_fixedNodes[p]].m_x[2] << "\n";
+                }
+                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();
+    btReducedSoftBodySolver* reducedSoftBodySolver = new btReducedSoftBodySolver();
+    reducedSoftBodySolver->setDamping(damping_alpha, damping_beta);
+    btVector3 gravity = btVector3(0, -10, 0);
+    reducedSoftBodySolver->setGravity(gravity);
+
+    btDeformableMultiBodyConstraintSolver* sol = new btDeformableMultiBodyConstraintSolver();
+    sol->setDeformableSolver(reducedSoftBodySolver);
+    m_solver = sol;
+
+    m_dynamicsWorld = new btDeformableMultiBodyDynamicsWorld(m_dispatcher, m_broadphase, sol, m_collisionConfiguration, reducedSoftBodySolver);
+    m_dynamicsWorld->setGravity(gravity);
+    m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
+
+    // create volumetric reduced deformable body
+    {   
+        std::string filepath("../../../examples/SoftDemo/");
+        std::string filename = filepath + "mesh.vtk";
+        btReducedSoftBody* rsb = btReducedSoftBodyHelpers::createFromVtkFile(getDeformableDynamicsWorld()->getWorldInfo(), filename.c_str());
+        
+        rsb->setReducedModes(start_mode, num_modes, rsb->m_nodes.size());
+        btReducedSoftBodyHelpers::readReducedDeformableInfoFromFiles(rsb, filepath.c_str());
+
+        getDeformableDynamicsWorld()->addSoftBody(rsb);
+        rsb->getCollisionShape()->setMargin(0.1);
+        // rsb->scale(btVector3(1, 1, 1));
+        rsb->translate(btVector3(0, 5, 0));  //TODO: add back translate and scale
+        // rsb->setTotalMass(0.5);
+        rsb->setStiffnessScale(0.5);
+        
+        // no fixed nodes
+        // rsb->setFixedNodes(0);
+
+        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);
+        
+        // rsb->setVelocity(btVector3(0, -COLLIDING_VELOCITY, 0));
+        // rsb->setRigidVelocity(btVector3(0, 1, 0));
+        // rsb->setRigidAngularVelocity(btVector3(1, 0, 0));
+        
+        // btDeformableGravityForce* gravity_force = new btDeformableGravityForce(gravity);
+        // getDeformableDynamicsWorld()->addForce(rsb, gravity_force);
+        // m_forces.push_back(gravity_force);
+    }
+    // create a static rigid box as the ground
+    {
+        btBoxShape* groundShape = createBoxShape(btVector3(btScalar(50.), btScalar(50.), btScalar(50.)));
+        m_collisionShapes.push_back(groundShape);
+
+        btTransform groundTransform;
+        groundTransform.setIdentity();
+        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(true);
+    getDeformableDynamicsWorld()->getSolverInfo().m_deformable_erp = 0.3;
+    getDeformableDynamicsWorld()->getSolverInfo().m_deformable_maxErrorReduction = btScalar(200);
+    getDeformableDynamicsWorld()->getSolverInfo().m_leastSquaresResidualThreshold = 1e-3;
+    getDeformableDynamicsWorld()->getSolverInfo().m_splitImpulse = true;
+    getDeformableDynamicsWorld()->getSolverInfo().m_numIterations = 100;
+    // add a few rigid bodies
+    // Ctor_RbUpStack();        // TODO: no rigid body for now
+    m_guiHelper->autogenerateGraphicsObjects(m_dynamicsWorld);
+    
+    // {
+    //     SliderParams slider("Young's Modulus", &E);
+    //     slider.m_minVal = 0;
+    //     slider.m_maxVal = 2000;
+    //     if (m_guiHelper->getParameterInterface())
+    //         m_guiHelper->getParameterInterface()->registerSliderFloatParameter(slider);
+    // }
+    // {
+    //     SliderParams slider("Poisson Ratio", &nu);
+    //     slider.m_minVal = 0.05;
+    //     slider.m_maxVal = 0.49;
+    //     if (m_guiHelper->getParameterInterface())
+    //         m_guiHelper->getParameterInterface()->registerSliderFloatParameter(slider);
+    // }
+    // {
+    //     SliderParams slider("Mass Damping", &damping_alpha);
+    //     slider.m_minVal = 0;
+    //     slider.m_maxVal = 1;
+    //     if (m_guiHelper->getParameterInterface())
+    //         m_guiHelper->getParameterInterface()->registerSliderFloatParameter(slider);
+    // }
+    // {
+    //     SliderParams slider("Stiffness Damping", &damping_beta);
+    //     slider.m_minVal = 0;
+    //     slider.m_maxVal = 0.1;
+    //     if (m_guiHelper->getParameterInterface())
+    //         m_guiHelper->getParameterInterface()->registerSliderFloatParameter(slider);
+    // }
+}
+
+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);
+}
+
+

examples/ReducedDeformableDemo/FreeFall.h

@@ -0,0 +1,19 @@
+/*
+ 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.
+ */
+
+#ifndef _REDUCED_FREE_FALL_H
+#define _REDUCED_FREE_FALL_H
+
+class CommonExampleInterface* ReducedFreeFallCreateFunc(struct CommonExampleOptions& options);
+
+#endif  //_REDUCED_FREE_FALL_H

src/BulletSoftBody/BulletReducedSoftBody/btReducedSoftBody.cpp

@@ -119,20 +119,9 @@ void btReducedSoftBody::setMassScale(const btScalar rho)
   m_rhoScale = rho;
 }
 
-void btReducedSoftBody::setFixedNodes()
+void btReducedSoftBody::setFixedNodes(const int n_node)
 {
-  // for (int i = 0; i < m_nFull; ++i)
-  // {
-  //   if (abs(m_nodes[i].m_x[2] - (-2)) < 1e-3)
-  //     m_fixedNodes.push_back(i);
-  // }
-  m_fixedNodes.push_back(0);
-  // m_fixedNodes.push_back(1);
-  m_fixedNodes.push_back(2);
-  // m_fixedNodes.push_back(3);
-
-  // m_fixedNodes.push_back(15);
-  // m_fixedNodes.push_back(18);
+  m_fixedNodes.push_back(n_node);
 }
 
 void btReducedSoftBody::internalInitialization()
@@ -460,6 +449,9 @@ void btReducedSoftBody::applyFullSpaceImpulse(const btVector3& impulse, const bt
   // update reduced dofs
   updateReducedDofs(dt);
 
+  // internal force
+  // applyReducedInternalForce(0, 0.01); // TODO: this should be necessary, but no obvious effects. Check again.
+
   // update local moment arm
   updateLocalMomentArm();
   updateExternalForceProjectMatrix(true);

src/BulletSoftBody/BulletReducedSoftBody/btReducedSoftBody.h

@@ -102,7 +102,7 @@ class btReducedSoftBody : public btSoftBody
 
   void setMassScale(const btScalar rho);
 
-  void setFixedNodes();
+  void setFixedNodes(const int n_node);
 
   //
   // various internal updates

src/BulletSoftBody/BulletReducedSoftBody/btReducedSoftBodySolver.cpp

@@ -106,7 +106,7 @@ void btReducedSoftBodySolver::applyTransforms(btScalar timeStep)
 
 void btReducedSoftBodySolver::solveConstraints(btScalar timeStep)
 {
-  for (int iter = 0; iter < 100; ++iter)
+  for (int iter = 0; iter < 100; ++iter)  // TODO: add a fllag for this.
   {
     for (int i = 0; i < m_softBodies.size(); ++i)
     {