ENH: Add option to have 'fixed' and 'real-time' time stepping schemes

Source/DynamicalModels/ObjectModels/imstkDynamicalModel.h

@@ -41,6 +41,15 @@ enum class DynamicalModelType
     none
 };
 
+///
+/// \brief Type of the update of the state of the body
+///
+enum class TimeSteppingType
+{
+    realTime,
+    fixed
+};
+
 ///
 /// \class DynamicalModel
 ///
@@ -63,6 +72,7 @@ public:
         none
     };
 
+
 public:
     ///
     /// \brief Constructor
@@ -119,11 +129,27 @@ public:
     ///
     virtual void updatePhysicsGeometry(){};
 
+    ///
+    /// \brief Set the time step size
+    ///
+    virtual void setTimeStep(const double timeStep) = 0;
+
+    ///
+    /// \brief Returns the time step size
+    ///
+    virtual double getTimeStep() const = 0;
+
     ///
     /// \brief Initialize the dynamical model
     ///
     virtual bool initialize() = 0;
 
+    ///
+    /// \brief Set the type of approach used to update the time step size after every frame
+    ///
+    virtual void setTimeStepSizeType(const TimeSteppingType type){ m_timeStepSizeType = type; }
+    TimeSteppingType getTimeStepSizeType(){ return m_timeStepSizeType; }
+
 protected:
 
     DynamicalModelType m_type; ///> Mathematical model type
@@ -134,6 +160,8 @@ protected:
     std::shared_ptr<StateType> m_previousState;     ///> Previous state
 
     std::size_t m_numDOF; ///> Total number of degree of freedom
+
+    TimeSteppingType m_timeStepSizeType = TimeSteppingType::fixed;
 };
 } // imstk
 

Source/DynamicalModels/ObjectModels/imstkFEMDeformableBodyModel.cpp

@@ -673,4 +673,11 @@ FEMDeformableBodyModel::getContactForce()
 {
     return m_Fcontact;
 }
+
+void
+FEMDeformableBodyModel::setFixedSizeTimeStepping()
+{
+    m_timeStepSizeType = TimeSteppingType::fixed;
+    m_timeIntegrator->setTimestepSizeToDefault();
+}
 } // imstk
\ No newline at end of file

Source/DynamicalModels/ObjectModels/imstkFEMDeformableBodyModel.h

@@ -233,6 +233,21 @@ public:
     ///
     std::vector<std::size_t>& getFixNodeIds() { return m_fixedNodeIds; }
 
+    ///
+    /// \brief Set the time step size
+    ///
+    virtual void setTimeStep(const double timeStep) { m_timeIntegrator->setTimestepSize(timeStep); };
+
+    ///
+    /// \brief Returns the time step size
+    ///
+    virtual double getTimeStep() const { return m_timeIntegrator->getTimestepSize(); };
+
+    ///
+    /// \brief Set the time step size to fixed size
+    ///
+    void setFixedSizeTimeStepping();
+
 protected:
     std::shared_ptr<InternalForceModel> m_internalForceModel;       ///> Mathematical model for intenal forces
     std::shared_ptr<TimeIntegrator>     m_timeIntegrator;           ///> Time integrator

Source/DynamicalModels/ObjectModels/imstkPbdModel.cpp

@@ -69,6 +69,7 @@ PbdModel::configure(const int nCons, ...)
         this->setGravity(g);
 
         this->setTimeStep(va_arg(args, double));
+        this->setDefaultTimeStep(m_dt);
 
         char *s = va_arg(args, char*);
         if (strlen(s) > 0)
@@ -611,6 +612,16 @@ PbdModel::updatePbdStateFromPhysicsGeometry()
     m_currentState->setPositions(m_mesh->getVertexPositions());
 }
 
+void
+PbdModel::setTimeStepSizeType(const TimeSteppingType type)
+{
+    m_timeStepSizeType = type;
+    if (type == TimeSteppingType::fixed)
+    {
+        m_dt = m_DefaultDt;
+    }
+}
+
 void
 PbdModel::setViscousDamping(const double damping)
 {

Source/DynamicalModels/ObjectModels/imstkPbdModel.h

@@ -167,11 +167,18 @@ public:
     /// \brief Set the time step size
     ///
     void setTimeStep(const double timeStep) { m_dt = timeStep; };
+    void setDefaultTimeStep(const double timeStep) { m_DefaultDt = timeStep; };
+
+    ///
+    /// \brief Set the time step size to fixed size
+    ///
+    void setTimeStepSizeType(const TimeSteppingType type) override;
 
     ///
     /// \brief Returns the time step size
     ///
     double getTimeStep() const { return m_dt; };
+    double getDefaultTimeStep() const { return m_DefaultDt; };
 
     ///
     /// \brief Set the gravity
@@ -250,6 +257,7 @@ protected:
     double m_proximity;                     ///> Proximity for collisions
 
     double m_dt;                            ///> Time step size
+    double m_DefaultDt;                     ///> Default Time step size
 };
 } // imstk
 

Source/SimulationManager/imstkSceneManager.cpp

@@ -145,6 +145,36 @@ SceneManager::runModule()
     {
         controller->setTrackerToOutOfDate();
     }
+<<<<<<< HEAD
+=======
+
+    auto timeElapsed = wwt.getTimeElapsed(StopWatch::TimeUnitType::seconds);
+
+    // Update time step size of the dynamic objects
+    for (auto obj : m_scene->getSceneObjects())
+    {
+        if (obj->getType() == SceneObject::Type::Pbd)
+        {
+            if (auto dynaObj = std::dynamic_pointer_cast<PbdObject>(obj))
+            {
+                if (dynaObj->getDynamicalModel()->getTimeStepSizeType() == TimeSteppingType::realTime)
+                {
+                    dynaObj->getDynamicalModel()->setTimeStep(timeElapsed);
+                }
+            }
+        }
+        else if (obj->getType() == SceneObject::Type::FEMDeformable)
+        {
+            if (auto dynaObj = std::dynamic_pointer_cast<DeformableObject>(obj))
+            {
+                if (dynaObj->getDynamicalModel()->getTimeStepSizeType() == TimeSteppingType::realTime)
+                {
+                    dynaObj->getDynamicalModel()->setTimeStep(timeElapsed);
+                }
+            }
+        }
+    }
+>>>>>>> 2decf6e... initial
 }
 
 void

Source/TimeIntegrators/imstkTimeIntegrator.h

@@ -56,7 +56,7 @@ public:
     ///
     /// \brief Constructor
     ///
-    TimeIntegrator(Type type, double dT) : m_type(type), m_dT(dT){}
+    TimeIntegrator(Type type, double dT) : m_type(type), m_dT(dT), m_defaultDt(dT){}
 
     ///
     /// \brief Destructor
@@ -73,6 +73,13 @@ public:
     ///
     void setTimestepSize(const double dT){ m_dT = dT; }
     double getTimestepSize() const { return m_dT; }
+    void setTimestepSizeToDefault(){ m_dT = m_defaultDt; }
+
+    ///
+    /// \brief Set/Get the time step size
+    ///
+    void setDefaultTimestepSize(const double dT){ m_defaultDt = dT; }
+    double getDefaultTimestepSize() const { return m_defaultDt; }
 
     ///
     /// \brief Update states given the updates in different forms
@@ -85,6 +92,7 @@ public:
 protected:
     Type m_type; ///> Type of the time integrator
     double m_dT; ///> Delta T
+    double m_defaultDt;
 };
 } // imstk