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add newton solver

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This commit is contained in:
Xuchen Han
2019-08-27 20:54:40 -07:00
parent c722630fc7
commit d4a15e016e
12 changed files with 566 additions and 62 deletions
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270
src/BulletSoftBody/btDeformableLagrangianForce.h
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@@ -18,6 +18,7 @@
#include "btSoftBody.h"
#include <LinearMath/btHashMap.h>
#include <iostream>
enum btDeformableLagrangianForceType
{
@@ -40,12 +41,21 @@ public:
virtual ~btDeformableLagrangianForce(){}
virtual void addScaledImplicitForce(btScalar scale, TVStack& force) = 0;
// add all forces
virtual void addScaledForces(btScalar scale, TVStack& force) = 0;
virtual void addScaledForceDifferential(btScalar scale, const TVStack& dv, TVStack& df) = 0;
// add damping df
virtual void addScaledDampingForceDifferential(btScalar scale, const TVStack& dv, TVStack& df) = 0;
// add elastic df
virtual void addScaledElasticForceDifferential(btScalar scale, const TVStack& dx, TVStack& df) = 0;
// add all forces that are explicit in explicit solve
virtual void addScaledExplicitForce(btScalar scale, TVStack& force) = 0;
// add all damping forces
virtual void addScaledDampingForce(btScalar scale, TVStack& force) = 0;
virtual btDeformableLagrangianForceType getForceType() = 0;
virtual void reinitialize(bool nodeUpdated)
@@ -71,5 +81,261 @@ public:
{
m_nodes = nodes;
}
virtual btMatrix3x3 Ds(int id0, int id1, int id2, int id3, const TVStack& dx)
{
btVector3 c1 = dx[id1] - dx[id0];
btVector3 c2 = dx[id2] - dx[id0];
btVector3 c3 = dx[id3] - dx[id0];
btMatrix3x3 dF(c1.getX(), c2.getX(), c3.getX(),
c1.getY(), c2.getY(), c3.getY(),
c1.getZ(), c2.getZ(), c3.getZ());
return dF;
}
virtual void testDerivative()
{
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].m_q += btVector3(randomDouble(-.1, .1), randomDouble(-.1, .1), randomDouble(-.1, .1));
}
psb->updateDeformation();
}
TVStack dx;
dx.resize(getNumNodes());
TVStack dphi_dx;
dphi_dx.resize(dx.size());
for (int i =0; i < dphi_dx.size();++i)
{
dphi_dx[i].setZero();
}
addScaledForces(-1, dphi_dx);
// write down the current position
TVStack x;
x.resize(dx.size());
int 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)
{
x[counter] = psb->m_nodes[j].m_q;
counter++;
}
}
counter = 0;
// populate dx with random vectors
for (int i = 0; i < dx.size(); ++i)
{
dx[i].setX(randomDouble(-1, 1));
dx[i].setY(randomDouble(-1, 1));
dx[i].setZ(randomDouble(-1, 1));
}
btAlignedObjectArray<double> errors;
double h = 1;
for (int it = 0; it < 10; ++it)
{
for (int i = 0; i < dx.size(); ++i)
{
dx[i] *= 0.5;
}
// get dphi/dx * dx
double dphi = 0;
for (int i = 0; i < dx.size(); ++i)
{
dphi += dphi_dx[i].dot(dx[i]);
}
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].m_q = x[counter] + dx[counter];
counter++;
}
psb->updateDeformation();
}
counter = 0;
double f1 = totalElasticEnergy();
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].m_q = x[counter] - dx[counter];
counter++;
}
psb->updateDeformation();
}
counter = 0;
double f2 = totalElasticEnergy();
//restore m_q
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].m_q = x[counter];
counter++;
}
psb->updateDeformation();
}
counter = 0;
double error = f1-f2-2*dphi;
errors.push_back(error);
std::cout << "Iteration = " << it <<", f1 = " << f1 << ", f2 = " << f2 << ", error = " << error << std::endl;
}
for (int i = 1; i < errors.size(); ++i)
{
std::cout << "Iteration = " << i << ", ratio = " << errors[i-1]/errors[i] << std::endl;
}
}
virtual void testHessian()
{
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].m_q += btVector3(randomDouble(-.1, .1), randomDouble(-.1, .1), randomDouble(-.1, .1));
}
psb->updateDeformation();
}
TVStack dx;
dx.resize(getNumNodes());
TVStack df;
df.resize(dx.size());
TVStack f1;
f1.resize(dx.size());
TVStack f2;
f2.resize(dx.size());
// write down the current position
TVStack x;
x.resize(dx.size());
int 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)
{
x[counter] = psb->m_nodes[j].m_q;
counter++;
}
}
counter = 0;
// populate dx with random vectors
for (int i = 0; i < dx.size(); ++i)
{
dx[i].setX(randomDouble(-1, 1));
dx[i].setY(randomDouble(-1, 1));
dx[i].setZ(randomDouble(-1, 1));
}
btAlignedObjectArray<double> errors;
for (int it = 0; it < 10; ++it)
{
for (int i = 0; i < dx.size(); ++i)
{
dx[i] *= 0.5;
}
// get df
for (int i =0; i < df.size();++i)
{
df[i].setZero();
f1[i].setZero();
f2[i].setZero();
}
//set df
addScaledElasticForceDifferential(-1, dx, df);
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].m_q = x[counter] + dx[counter];
counter++;
}
psb->updateDeformation();
}
counter = 0;
//set f1
addScaledForces(-1, f1);
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].m_q = x[counter] - dx[counter];
counter++;
}
psb->updateDeformation();
}
counter = 0;
//set f2
addScaledForces(-1, f2);
//restore m_q
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].m_q = x[counter];
counter++;
}
psb->updateDeformation();
}
counter = 0;
double error = 0;
for (int i = 0; i < df.size();++i)
{
btVector3 error_vector = f1[i]-f2[i]-2*df[i];
error += error_vector.length2();
}
error = btSqrt(error);
errors.push_back(error);
std::cout << "Iteration = " << it << ", error = " << error << std::endl;
}
for (int i = 1; i < errors.size(); ++i)
{
std::cout << "Iteration = " << i << ", ratio = " << errors[i-1]/errors[i] << std::endl;
}
}
virtual double totalElasticEnergy()
{
return 0;
}
double randomDouble(double low, double high)
{
return low + static_cast<double>(rand()) / RAND_MAX * (high - low);
}
};
#endif /* BT_DEFORMABLE_LAGRANGIAN_FORCE */