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Diffstat (limited to 'extern/bullet2/src/BulletSoftBody/btDeformableBodySolver.h')
| -rw-r--r-- | extern/bullet2/src/BulletSoftBody/btDeformableBodySolver.h | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/extern/bullet2/src/BulletSoftBody/btDeformableBodySolver.h b/extern/bullet2/src/BulletSoftBody/btDeformableBodySolver.h new file mode 100644 index 00000000000..ae674d6e892 --- /dev/null +++ b/extern/bullet2/src/BulletSoftBody/btDeformableBodySolver.h @@ -0,0 +1,160 @@ +/* + Written by Xuchen Han <xuchenhan2015@u.northwestern.edu> + + 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 BT_DEFORMABLE_BODY_SOLVERS_H +#define BT_DEFORMABLE_BODY_SOLVERS_H + +#include "btSoftBodySolvers.h" +#include "btDeformableBackwardEulerObjective.h" +#include "btDeformableMultiBodyDynamicsWorld.h" +#include "BulletDynamics/Featherstone/btMultiBodyLinkCollider.h" +#include "BulletDynamics/Featherstone/btMultiBodyConstraint.h" +#include "btConjugateResidual.h" +#include "btConjugateGradient.h" +struct btCollisionObjectWrapper; +class btDeformableBackwardEulerObjective; +class btDeformableMultiBodyDynamicsWorld; + +class btDeformableBodySolver : public btSoftBodySolver +{ + typedef btAlignedObjectArray<btVector3> TVStack; + +protected: + int m_numNodes; // total number of deformable body nodes + TVStack m_dv; // v_{n+1} - v_n + TVStack m_backup_dv; // backed up dv + TVStack m_ddv; // incremental dv + TVStack m_residual; // rhs of the linear solve + btAlignedObjectArray<btSoftBody*> m_softBodies; // all deformable bodies + TVStack m_backupVelocity; // backed up v, equals v_n for implicit, equals v_{n+1}^* for explicit + btScalar m_dt; // dt + btConjugateGradient<btDeformableBackwardEulerObjective> m_cg; // CG solver + btConjugateResidual<btDeformableBackwardEulerObjective> m_cr; // CR solver + bool m_implicit; // use implicit scheme if true, explicit scheme if false + int m_maxNewtonIterations; // max number of newton iterations + btScalar m_newtonTolerance; // stop newton iterations if f(x) < m_newtonTolerance + bool m_lineSearch; // If true, use newton's method with line search under implicit scheme +public: + // handles data related to objective function + btDeformableBackwardEulerObjective* m_objective; + bool m_useProjection; + + btDeformableBodySolver(); + + virtual ~btDeformableBodySolver(); + + virtual SolverTypes getSolverType() const + { + return DEFORMABLE_SOLVER; + } + + // update soft body normals + virtual void updateSoftBodies(); + + virtual btScalar solveContactConstraints(btCollisionObject** deformableBodies, int numDeformableBodies, const btContactSolverInfo& infoGlobal); + + // solve the momentum equation + virtual void solveDeformableConstraints(btScalar solverdt); + + // resize/clear data structures + void reinitialize(const btAlignedObjectArray<btSoftBody*>& softBodies, btScalar dt); + + // set up contact constraints + void setConstraints(const btContactSolverInfo& infoGlobal); + + // add in elastic forces and gravity to obtain v_{n+1}^* and calls predictDeformableMotion + virtual void predictMotion(btScalar solverdt); + + // move to temporary position x_{n+1}^* = x_n + dt * v_{n+1}^* + // x_{n+1}^* is stored in m_q + void predictDeformableMotion(btSoftBody* psb, btScalar dt); + + // save the current velocity to m_backupVelocity + void backupVelocity(); + + // set m_dv and m_backupVelocity to desired value to prepare for momentum solve + void setupDeformableSolve(bool implicit); + + // set the current velocity to that backed up in m_backupVelocity + void revertVelocity(); + + // set velocity to m_dv + m_backupVelocity + void updateVelocity(); + + // update the node count + bool updateNodes(); + + // calculate the change in dv resulting from the momentum solve + void computeStep(TVStack& ddv, const TVStack& residual); + + // calculate the change in dv resulting from the momentum solve when line search is turned on + btScalar computeDescentStep(TVStack& ddv, const TVStack& residual, bool verbose = false); + + virtual void copySoftBodyToVertexBuffer(const btSoftBody* const softBody, btVertexBufferDescriptor* vertexBuffer) {} + + // process collision between deformable and rigid + virtual void processCollision(btSoftBody* softBody, const btCollisionObjectWrapper* collisionObjectWrap) + { + softBody->defaultCollisionHandler(collisionObjectWrap); + } + + // process collision between deformable and deformable + virtual void processCollision(btSoftBody* softBody, btSoftBody* otherSoftBody) + { + softBody->defaultCollisionHandler(otherSoftBody); + } + + // If true, implicit time stepping scheme is used. + // Otherwise, explicit time stepping scheme is used + void setImplicit(bool implicit); + + // If true, newton's method with line search is used when implicit time stepping scheme is turned on + void setLineSearch(bool lineSearch); + + // set temporary position x^* = x_n + dt * v + // update the deformation gradient at position x^* + void updateState(); + + // set dv = dv + scale * ddv + void updateDv(btScalar scale = 1); + + // set temporary position x^* = x_n + dt * v^* + void updateTempPosition(); + + // save the current dv to m_backup_dv; + void backupDv(); + + // set dv to the backed-up value + void revertDv(); + + // set dv = dv + scale * ddv + // set v^* = v_n + dv + // set temporary position x^* = x_n + dt * v^* + // update the deformation gradient at position x^* + void updateEnergy(btScalar scale); + + // calculates the appropriately scaled kinetic energy in the system, which is + // 1/2 * dv^T * M * dv + // used in line search + btScalar kineticEnergy(); + + // unused functions + virtual void optimize(btAlignedObjectArray<btSoftBody*>& softBodies, bool forceUpdate = false) {} + virtual void solveConstraints(btScalar dt) {} + virtual bool checkInitialized() { return true; } + virtual void copyBackToSoftBodies(bool bMove = true) {} +}; + +#endif /* btDeformableBodySolver_h */ |