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
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
|
/*
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.
*/
#include "btDeformableBackwardEulerObjective.h"
#include "btPreconditioner.h"
#include "LinearMath/btQuickprof.h"
btDeformableBackwardEulerObjective::btDeformableBackwardEulerObjective(btAlignedObjectArray<btSoftBody *>& softBodies, const TVStack& backup_v)
: m_softBodies(softBodies)
, m_projection(softBodies)
, m_backupVelocity(backup_v)
, m_implicit(false)
{
m_massPreconditioner = new MassPreconditioner(m_softBodies);
m_KKTPreconditioner = new KKTPreconditioner(m_softBodies, m_projection, m_lf, m_dt, m_implicit);
m_preconditioner = m_KKTPreconditioner;
}
btDeformableBackwardEulerObjective::~btDeformableBackwardEulerObjective()
{
delete m_KKTPreconditioner;
delete m_massPreconditioner;
}
void btDeformableBackwardEulerObjective::reinitialize(bool nodeUpdated, btScalar dt)
{
BT_PROFILE("reinitialize");
if (dt > 0)
{
setDt(dt);
}
if(nodeUpdated)
{
updateId();
}
for (int i = 0; i < m_lf.size(); ++i)
{
m_lf[i]->reinitialize(nodeUpdated);
}
m_projection.reinitialize(nodeUpdated);
// m_preconditioner->reinitialize(nodeUpdated);
}
void btDeformableBackwardEulerObjective::setDt(btScalar dt)
{
m_dt = dt;
}
void btDeformableBackwardEulerObjective::multiply(const TVStack& x, TVStack& b) const
{
BT_PROFILE("multiply");
// add in the mass term
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];
b[counter] = (node.m_im == 0) ? btVector3(0,0,0) : x[counter] / node.m_im;
++counter;
}
}
for (int i = 0; i < m_lf.size(); ++i)
{
// add damping matrix
m_lf[i]->addScaledDampingForceDifferential(-m_dt, x, b);
if (m_implicit)
{
m_lf[i]->addScaledElasticForceDifferential(-m_dt*m_dt, x, b);
}
}
int offset = m_nodes.size();
for (int i = offset; i < b.size(); ++i)
{
b[i].setZero();
}
// add in the lagrange multiplier terms
for (int c = 0; c < m_projection.m_lagrangeMultipliers.size(); ++c)
{
// C^T * lambda
const LagrangeMultiplier& lm = m_projection.m_lagrangeMultipliers[c];
for (int i = 0; i < lm.m_num_nodes; ++i)
{
for (int j = 0; j < lm.m_num_constraints; ++j)
{
b[lm.m_indices[i]] += x[offset+c][j] * lm.m_weights[i] * lm.m_dirs[j];
}
}
// C * x
for (int d = 0; d < lm.m_num_constraints; ++d)
{
for (int i = 0; i < lm.m_num_nodes; ++i)
{
b[offset+c][d] += lm.m_weights[i] * x[lm.m_indices[i]].dot(lm.m_dirs[d]);
}
}
}
}
void btDeformableBackwardEulerObjective::updateVelocity(const TVStack& dv)
{
for (int i = 0; i < m_softBodies.size(); ++i)
{
btSoftBody* psb = m_softBodies[i];
for (int j = 0; j < psb->m_nodes.size(); ++j)
{
btSoftBody::Node& node = psb->m_nodes[j];
node.m_v = m_backupVelocity[node.index] + dv[node.index];
}
}
}
void btDeformableBackwardEulerObjective::applyForce(TVStack& force, bool setZero)
{
size_t counter = 0;
for (int i = 0; i < m_softBodies.size(); ++i)
{
btSoftBody* psb = m_softBodies[i];
if (!psb->isActive())
{
counter += psb->m_nodes.size();
continue;
}
for (int j = 0; j < psb->m_nodes.size(); ++j)
{
btScalar one_over_mass = (psb->m_nodes[j].m_im == 0) ? 0 : psb->m_nodes[j].m_im;
psb->m_nodes[j].m_v += one_over_mass * force[counter++];
}
}
if (setZero)
{
for (int i = 0; i < force.size(); ++i)
force[i].setZero();
}
}
void btDeformableBackwardEulerObjective::computeResidual(btScalar dt, TVStack &residual)
{
BT_PROFILE("computeResidual");
// add implicit force
for (int i = 0; i < m_lf.size(); ++i)
{
if (m_implicit)
{
m_lf[i]->addScaledForces(dt, residual);
}
else
{
m_lf[i]->addScaledDampingForce(dt, residual);
}
}
// m_projection.project(residual);
}
btScalar btDeformableBackwardEulerObjective::computeNorm(const TVStack& residual) const
{
btScalar mag = 0;
for (int i = 0; i < residual.size(); ++i)
{
mag += residual[i].length2();
}
return std::sqrt(mag);
}
btScalar btDeformableBackwardEulerObjective::totalEnergy(btScalar dt)
{
btScalar e = 0;
for (int i = 0; i < m_lf.size(); ++i)
{
e += m_lf[i]->totalEnergy(dt);
}
return e;
}
void btDeformableBackwardEulerObjective::applyExplicitForce(TVStack& force)
{
for (int i = 0; i < m_softBodies.size(); ++i)
{
m_softBodies[i]->advanceDeformation();
}
for (int i = 0; i < m_lf.size(); ++i)
{
m_lf[i]->addScaledExplicitForce(m_dt, force);
}
applyForce(force, true);
}
void btDeformableBackwardEulerObjective::initialGuess(TVStack& dv, const TVStack& residual)
{
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)
{
dv[counter] = psb->m_nodes[j].m_im * residual[counter];
++counter;
}
}
}
//set constraints as projections
void btDeformableBackwardEulerObjective::setConstraints(const btContactSolverInfo& infoGlobal)
{
m_projection.setConstraints(infoGlobal);
}
void btDeformableBackwardEulerObjective::applyDynamicFriction(TVStack& r)
{
m_projection.applyDynamicFriction(r);
}
|