1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
|
/*
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_BACKWARD_EULER_OBJECTIVE_H
#define BT_BACKWARD_EULER_OBJECTIVE_H
//#include "btConjugateGradient.h"
#include "btDeformableLagrangianForce.h"
#include "btDeformableMassSpringForce.h"
#include "btDeformableGravityForce.h"
#include "btDeformableCorotatedForce.h"
#include "btDeformableMousePickingForce.h"
#include "btDeformableLinearElasticityForce.h"
#include "btDeformableNeoHookeanForce.h"
#include "btDeformableContactProjection.h"
#include "btPreconditioner.h"
#include "btDeformableMultiBodyDynamicsWorld.h"
#include "LinearMath/btQuickprof.h"
class btDeformableBackwardEulerObjective
{
public:
typedef btAlignedObjectArray<btVector3> TVStack;
btScalar m_dt;
btAlignedObjectArray<btDeformableLagrangianForce*> m_lf;
btAlignedObjectArray<btSoftBody*>& m_softBodies;
Preconditioner* m_preconditioner;
btDeformableContactProjection m_projection;
const TVStack& m_backupVelocity;
btAlignedObjectArray<btSoftBody::Node*> m_nodes;
bool m_implicit;
MassPreconditioner* m_massPreconditioner;
KKTPreconditioner* m_KKTPreconditioner;
btDeformableBackwardEulerObjective(btAlignedObjectArray<btSoftBody*>& softBodies, const TVStack& backup_v);
virtual ~btDeformableBackwardEulerObjective();
void initialize() {}
// compute the rhs for CG solve, i.e, add the dt scaled implicit force to residual
void computeResidual(btScalar dt, TVStack& residual);
// add explicit force to the velocity
void applyExplicitForce(TVStack& force);
// apply force to velocity and optionally reset the force to zero
void applyForce(TVStack& force, bool setZero);
// compute the norm of the residual
btScalar computeNorm(const TVStack& residual) const;
// compute one step of the solve (there is only one solve if the system is linear)
void computeStep(TVStack& dv, const TVStack& residual, const btScalar& dt);
// perform A*x = b
void multiply(const TVStack& x, TVStack& b) const;
// set initial guess for CG solve
void initialGuess(TVStack& dv, const TVStack& residual);
// reset data structure and reset dt
void reinitialize(bool nodeUpdated, btScalar dt);
void setDt(btScalar dt);
// add friction force to residual
void applyDynamicFriction(TVStack& r);
// add dv to velocity
void updateVelocity(const TVStack& dv);
//set constraints as projections
void setConstraints(const btContactSolverInfo& infoGlobal);
// update the projections and project the residual
void project(TVStack& r)
{
BT_PROFILE("project");
m_projection.project(r);
}
// perform precondition M^(-1) x = b
void precondition(const TVStack& x, TVStack& b)
{
m_preconditioner->operator()(x, b);
}
// reindex all the vertices
virtual void updateId()
{
size_t node_id = 0;
size_t face_id = 0;
m_nodes.clear();
for (int i = 0; i < m_softBodies.size(); ++i)
{
btSoftBody* psb = m_softBodies[i];
for (int j = 0; j < psb->m_nodes.size(); ++j)
{
psb->m_nodes[j].index = node_id;
m_nodes.push_back(&psb->m_nodes[j]);
++node_id;
}
for (int j = 0; j < psb->m_faces.size(); ++j)
{
psb->m_faces[j].m_index = face_id;
++face_id;
}
}
}
const btAlignedObjectArray<btSoftBody::Node*>* getIndices() const
{
return &m_nodes;
}
void setImplicit(bool implicit)
{
m_implicit = implicit;
}
// Calculate the total potential energy in the system
btScalar totalEnergy(btScalar dt);
void addLagrangeMultiplier(const TVStack& vec, TVStack& extended_vec)
{
extended_vec.resize(vec.size() + m_projection.m_lagrangeMultipliers.size());
for (int i = 0; i < vec.size(); ++i)
{
extended_vec[i] = vec[i];
}
int offset = vec.size();
for (int i = 0; i < m_projection.m_lagrangeMultipliers.size(); ++i)
{
extended_vec[offset + i].setZero();
}
}
void addLagrangeMultiplierRHS(const TVStack& residual, const TVStack& m_dv, TVStack& extended_residual)
{
extended_residual.resize(residual.size() + m_projection.m_lagrangeMultipliers.size());
for (int i = 0; i < residual.size(); ++i)
{
extended_residual[i] = residual[i];
}
int offset = residual.size();
for (int i = 0; i < m_projection.m_lagrangeMultipliers.size(); ++i)
{
const LagrangeMultiplier& lm = m_projection.m_lagrangeMultipliers[i];
extended_residual[offset + i].setZero();
for (int d = 0; d < lm.m_num_constraints; ++d)
{
for (int n = 0; n < lm.m_num_nodes; ++n)
{
extended_residual[offset + i][d] += lm.m_weights[n] * m_dv[lm.m_indices[n]].dot(lm.m_dirs[d]);
}
}
}
}
void calculateContactForce(const TVStack& dv, const TVStack& rhs, TVStack& f)
{
size_t counter = 0;
for (int i = 0; i < m_softBodies.size(); ++i)
{
btSoftBody* psb = m_softBodies[i];
for (int j = 0; j < psb->m_nodes.size(); ++j)
{
const btSoftBody::Node& node = psb->m_nodes[j];
f[counter] = (node.m_im == 0) ? btVector3(0, 0, 0) : dv[counter] / node.m_im;
++counter;
}
}
for (int i = 0; i < m_lf.size(); ++i)
{
// add damping matrix
m_lf[i]->addScaledDampingForceDifferential(-m_dt, dv, f);
}
counter = 0;
for (; counter < f.size(); ++counter)
{
f[counter] = rhs[counter] - f[counter];
}
}
};
#endif /* btBackwardEulerObjective_h */
|