105 lines
2.9 KiB
C++
105 lines
2.9 KiB
C++
//
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// btBackwardEulerObjective.h
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// BulletSoftBody
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//
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// Created by Xuchen Han on 7/1/19.
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//
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#ifndef BT_BACKWARD_EULER_OBJECTIVE_H
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#define BT_BACKWARD_EULER_OBJECTIVE_H
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#include <functional>
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#include "btConjugateGradient.h"
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#include "btLagrangianForce.h"
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#include "btMassSpring.h"
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#include "btContactProjection.h"
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#include "btPreconditioner.h"
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#include "btDeformableRigidDynamicsWorld.h"
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class btDeformableRigidDynamicsWorld;
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class btBackwardEulerObjective
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{
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public:
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using TVStack = btAlignedObjectArray<btVector3>;
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btScalar m_dt;
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btConjugateGradient<btBackwardEulerObjective> cg;
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btDeformableRigidDynamicsWorld* m_world;
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btAlignedObjectArray<btLagrangianForce*> m_lf;
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btAlignedObjectArray<btSoftBody *>& m_softBodies;
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Preconditioner* m_preconditioner;
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btContactProjection projection;
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const TVStack& m_backupVelocity;
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btBackwardEulerObjective(btAlignedObjectArray<btSoftBody *>& softBodies, const TVStack& backup_v);
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virtual ~btBackwardEulerObjective() {}
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void initialize(){}
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// compute the rhs for CG solve, i.e, add the dt scaled implicit force to residual
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void computeResidual(btScalar dt, TVStack& residual) const;
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// add explicit force to the velocity
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void applyExplicitForce(TVStack& force);
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// apply force to velocity and optionally reset the force to zero
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void applyForce(TVStack& force, bool setZero);
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// compute the norm of the residual
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btScalar computeNorm(const TVStack& residual) const;
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// compute one step of the solve (there is only one solve if the system is linear)
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void computeStep(TVStack& dv, const TVStack& residual, const btScalar& dt);
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// perform A*x = b
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void multiply(const TVStack& x, TVStack& b) const;
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// update the constraints treated as projections
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void updateProjection(const TVStack& dv)
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{
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projection.update(dv, m_backupVelocity);
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}
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// set initial guess for CG solve
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void initialGuess(TVStack& dv, const TVStack& residual);
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// reset data structure
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void reinitialize(bool nodeUpdated);
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// enforce constraints in CG solve
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void enforceConstraint(TVStack& x)
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{
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projection.enforceConstraint(x);
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updateVelocity(x);
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}
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// add dv to velocity
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void updateVelocity(const TVStack& dv);
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//set constraints as projections
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void setConstraints()
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{
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projection.setConstraints();
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}
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// update the projections and project the residual
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void project(TVStack& r, const TVStack& dv)
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{
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updateProjection(dv);
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projection(r);
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}
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// perform precondition M^(-1) x = b
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void precondition(const TVStack& x, TVStack& b)
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{
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m_preconditioner->operator()(x,b);
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}
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virtual void setWorld(btDeformableRigidDynamicsWorld* world)
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{
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m_world = world;
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projection.setWorld(world);
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}
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};
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#endif /* btBackwardEulerObjective_h */
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