git-svn-id: https://reactphysics3d.googlecode.com/svn/trunk@87 92aac97c-a6ce-11dd-a772-7fcde58d38e6

sources/reactphysics3d/body/BodyState.cpp

@@ -64,6 +64,29 @@ void BodyState::recalculate() {
     spin = Quaternion(0, angularVelocity.getX(), angularVelocity.getY(), angularVelocity.getZ()) * orientation * 0.5;
 }
 
+// Compute the body state at time t + dt
+void computeAtTime(const Time& time, const Time& timeStep, const DerivativeBodyState& lastDerivativeBodyState) {
+
+    double t = time.getValue();             // Current time
+    double dt = timeStep.getValue();        // Timestep
+
+    // Compute the position at time t + dt
+    position = position + lastDerivativeBodyState.getLinearVelocity() * dt;
+
+    // Compute the linear momentum at time t + dt
+    linearMomentum = linearMomentum + lastDerivativeBodyState.force * dt;
+
+    // Compute the orientation at time t + dt
+    orientation = orientation + lastDerivativeBodyState.getSpin() * dt;
+
+    // Compute the angular momentum at time t + dt
+    angularMomentum = angularMomentum + lastDerivativeBodyState.torque * dt;
+
+    // Recalculate the secondary values of the body state
+    recalculate();
+}
+
+
 // Overloaded operator for the multiplication with a number
 BodyState BodyState::operator*(double number) const {
     // TODO : Implement this method

sources/reactphysics3d/body/BodyState.h

@@ -67,7 +67,10 @@ class BodyState {
         void setMassInverse(Kilogram massInverse);                              // Set the inverse of the mass
         void setInertiaTensorInverse(const Matrix3x3& inertiaTensorInverse);    // Set the inverse of the inertia tensor
 
-        void recalculate();             // Recalculate the secondary values of the BodyState
+        void recalculate();                                                                 // Recalculate the secondary values
+                                                                                            // of the BodyState from the primary ones
+        void computeAtTime(const Time& time, const Time& timeStep,
+                                              const DerivativeBodyState& lastDerivativeBodyState);      // Compute the body state at time t + dt
 
         // Overloaded operators
         BodyState operator*(double number) const;       // Overloaded operator for the multiplication with a number

sources/reactphysics3d/body/DerivativeBodyState.cpp

@@ -0,0 +1,43 @@
+/****************************************************************************
+* Copyright (C) 2009      Daniel Chappuis                                  *
+****************************************************************************
+* This file is part of ReactPhysics3D.                                     *
+*                                                                          *
+* ReactPhysics3D is free software: you can redistribute it and/or modify   *
+* it under the terms of the GNU General Public License as published by     *
+* the Free Software Foundation, either version 3 of the License, or        *
+* (at your option) any later version.                                      *
+*                                                                          *
+* ReactPhysics3D is distributed in the hope that it will be useful,        *
+* but WITHOUT ANY WARRANTY; without even the implied warranty of           *
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the             *
+* GNU General Public License for more details.                             *
+*                                                                          *
+* You should have received a copy of the GNU General Public License        *
+* along with ReactPhysics3D. If not, see <http://www.gnu.org/licenses/>.   *
+***************************************************************************/
+
+// Libraries
+#include "DerivativeBodyState.h"
+
+// We want to use the ReactPhysics3D namespace
+using namespace reactphysics3d;
+
+// Constructor
+DerivativeBodyState::DerivativeBodyState(const Vector3D& linearVelocity, const Vector3D& force, const Vector3D& torque,
+                            const Quaternion& spin) : linearVelocity(linearVelocity), force(force), torque(torque),
+                                                      spin(spin) {
+
+}
+
+// Copy-constructor
+DerivativeBodyState::DerivativeBodyState(const DerivativeBodyState& derivativeBodyState)
+                    : linearVelocity(derivativeBodyState.linearVelocity), force(derivativeBodyState.force),
+                      torque(derivativeBodyState.torque), spin(derivativeBodyState.spin) {
+
+}
+
+// Destructor
+DerivativeBodyState::~DerivativeBodyState() {
+
+}

sources/reactphysics3d/body/DerivativeBodyState.h

@@ -0,0 +1,79 @@
+/****************************************************************************
+* Copyright (C) 2009      Daniel Chappuis                                  *
+****************************************************************************
+* This file is part of ReactPhysics3D.                                     *
+*                                                                          *
+* ReactPhysics3D is free software: you can redistribute it and/or modify   *
+* it under the terms of the GNU General Public License as published by     *
+* the Free Software Foundation, either version 3 of the License, or        *
+* (at your option) any later version.                                      *
+*                                                                          *
+* ReactPhysics3D is distributed in the hope that it will be useful,        *
+* but WITHOUT ANY WARRANTY; without even the implied warranty of           *
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the             *
+* GNU General Public License for more details.                             *
+*                                                                          *
+* You should have received a copy of the GNU General Public License        *
+* along with ReactPhysics3D. If not, see <http://www.gnu.org/licenses/>.   *
+***************************************************************************/
+
+#ifndef DERIVATIVEBODYSTATE_H
+#define DERIVATIVEBODYSTATE_H
+
+// Libraries
+#include "../mathematics/mathematics.h"
+
+// Namespace ReactPhysics3D
+namespace reactphysics3d {
+
+/*  -------------------------------------------------------------------
+    Class DerivativeBodyState :
+        This class represents a derivative of a body state at time t.
+        This class is used in the numerical integrator to compute the
+        derivative of a body state at different times.
+    -------------------------------------------------------------------
+*/
+class DerivativeBodyState {
+    private :
+        Vector3D linearVelocity;            // Linear velocity of the body
+        Vector3D force;                     // Force applied to the body
+        Vector3D torque;                    // Torque applied to the body
+        Quaternion spin;                    // Quaternion spin of the body
+
+    public :
+        DerivativeBodyState(const Vector3D& linearVelocity, const Vector3D& force, const Vector3D& torque,
+                            const Quaternion& spin);                                                        // Constructor
+        DerivativeBodyState(const DerivativeBodyState& derivativeBodyState);                                // Copy-constructor
+        virtual ~DerivativeBodyState();                                                                     // Destructor
+
+        Vector3D getLinearVelocity() const;         // Return the linear velocity
+        Vector3D getForce() const;                  // Return the force
+        Vector3D getTorque() const;                 // Return the torque
+        Quaternion getSpin() const;                 // Return the spin
+};
+
+// --- Inline functions --- //
+
+// Return the linear velocity
+inline Vector3D DerivativeBodyState::getLinearVelocity() const {
+    return linearVelocity;
+}
+
+// Return the force
+inline Vector3D DerivativeBodyState::getForce() const {
+    return force;
+}
+
+// Return the torque
+inline Vector3D DerivativeBodyState::getTorque() const {
+    return torque;
+}
+
+// Return the spin
+inline Quaternion DerivativeBodyState::getSpin() const {
+    return spin;
+}
+
+}
+
+#endif