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add some documentation

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This commit is contained in:
Xuchen Han
2019-09-17 15:55:15 -07:00
parent ae42cc561e
commit d761b2cd68
14 changed files with 95 additions and 78 deletions
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11
src/BulletSoftBody/btDeformableNeoHookeanForce.h
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@@ -18,6 +18,7 @@ subject to the following restrictions:
#include "btDeformableLagrangianForce.h"
// This energy is as described in https://graphics.pixar.com/library/StableElasticity/paper.pdf
class btDeformableNeoHookeanForce : public btDeformableLagrangianForce
{
public:
@@ -48,6 +49,7 @@ public:
addScaledElasticForce(scale, force);
}
// The damping matrix is calculated using the time n state as described in https://www.math.ucla.edu/~jteran/papers/GSSJT15.pdf to allow line search
virtual void addScaledDampingForce(btScalar scale, TVStack& force)
{
if (m_mu_damp == 0 && m_lambda_damp == 0)
@@ -101,6 +103,7 @@ public:
return energy;
}
// The damping energy is formulated as in https://www.math.ucla.edu/~jteran/papers/GSSJT15.pdf to allow line search
virtual double totalDampingEnergy(btScalar dt)
{
double energy = 0;
@@ -174,6 +177,7 @@ public:
}
}
// The damping matrix is calculated using the time n state as described in https://www.math.ucla.edu/~jteran/papers/GSSJT15.pdf to allow line search
virtual void addScaledDampingForceDifferential(btScalar scale, const TVStack& dv, TVStack& df)
{
if (m_mu_damp == 0 && m_lambda_damp == 0)
@@ -251,6 +255,8 @@ public:
P = s.m_F * m_mu * ( 1. - 1. / (s.m_trace + 1.)) + s.m_cofF * (m_lambda * (s.m_J - 1.) - 0.75 * m_mu);
}
// Let P be the first piola stress.
// This function calculates the dP = dP/dF * dF
void firstPiolaDifferential(const btSoftBody::TetraScratch& s, const btMatrix3x3& dF, btMatrix3x3& dP)
{
dP = dF * m_mu * ( 1. - 1. / (s.m_trace + 1.)) + s.m_F * (2*m_mu) * DotProduct(s.m_F, dF) * (1./((1.+s.m_trace)*(1.+s.m_trace)));
@@ -259,6 +265,8 @@ public:
dP += s.m_cofF * m_lambda * DotProduct(s.m_cofF, dF);
}
// Let Q be the damping stress.
// This function calculates the dP = dQ/dF * dF
void firstPiolaDampingDifferential(const btSoftBody::TetraScratch& s, const btMatrix3x3& dF, btMatrix3x3& dP)
{
dP = dF * m_mu_damp * ( 1. - 1. / (s.m_trace + 1.)) + s.m_F * (2*m_mu_damp) * DotProduct(s.m_F, dF) * (1./((1.+s.m_trace)*(1.+s.m_trace)));
@@ -277,6 +285,9 @@ public:
return ans;
}
// Let C(A) be the cofactor of the matrix A
// Let H = the derivative of C(A) with respect to A evaluated at F = A
// This function calculates H*dF
void addScaledCofactorMatrixDifferential(const btMatrix3x3& F, const btMatrix3x3& dF, btScalar scale, btMatrix3x3& M)
{
M[0][0] += scale * (dF[1][1] * F[2][2] + F[1][1] * dF[2][2] - dF[2][1] * F[1][2] - F[2][1] * dF[1][2]);