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Switch mjData.{qH,qLD} from full ("M") to reduced ("C") inertia matrix structure.

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PiperOrigin-RevId: 758273074
Change-Id: If1a2e663ea70044694af985e0119afd6d58115ac
This commit is contained in:
Yuval Tassa
2025-05-13 10:19:22 -07:00
committed by Copybara-Service
parent 436b5a8e1f
commit 627fffdef9
18 changed files with 99 additions and 101 deletions
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src/engine/engine_forward.c
+9 -9
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@@ -836,7 +836,7 @@ static void mj_advance(const mjModel* m, mjData* d,
// Euler integrator, semi-implicit in velocity, possibly skipping factorisation
void mj_EulerSkip(const mjModel* m, mjData* d, int skipfactor) {
TM_START;
int nv = m->nv, nM = m->nM;
int nv = m->nv, nC = m->nC;
mj_markStack(d);
mjtNum* qfrc = mjSTACKALLOC(d, nv, mjtNum);
mjtNum* qacc = mjSTACKALLOC(d, nv, mjtNum);
@@ -861,20 +861,20 @@ void mj_EulerSkip(const mjModel* m, mjData* d, int skipfactor) {
else {
if (!skipfactor) {
// qH = M + h*diag(B)
mju_gather(d->qH, d->qM, d->mapM2M, nM);
mju_gather(d->qH, d->qM, d->mapM2C, nC);
for (int i=0; i < nv; i++) {
d->qH[d->M_rowadr[i] + d->M_rownnz[i] - 1] += m->opt.timestep * m->dof_damping[i];
d->qH[d->C_rowadr[i] + d->C_rownnz[i] - 1] += m->opt.timestep * m->dof_damping[i];
}
// factorize in-place
mj_factorI(d->qH, d->qHDiagInv, nv, d->M_rownnz, d->M_rowadr, m->dof_simplenum, d->M_colind);
mj_factorI(d->qH, d->qHDiagInv, nv, d->C_rownnz, d->C_rowadr, m->dof_simplenum, d->C_colind);
}
// solve
mju_add(qfrc, d->qfrc_smooth, d->qfrc_constraint, nv);
mju_copy(qacc, qfrc, m->nv);
mj_solveLD(qacc, d->qH, d->qHDiagInv, nv, 1,
d->M_rownnz, d->M_rowadr, m->dof_simplenum, d->M_colind);
d->C_rownnz, d->C_rowadr, m->dof_simplenum, d->C_colind);
}
// advance state and time
@@ -1003,7 +1003,7 @@ void mj_RungeKutta(const mjModel* m, mjData* d, int N) {
// fully implicit in velocity, possibly skipping factorization
void mj_implicitSkip(const mjModel* m, mjData* d, int skipfactor) {
TM_START;
int nv = m->nv, nM = m->nM, nD = m->nD;
int nv = m->nv, nM = m->nM, nD = m->nD, nC = m->nC;
mj_markStack(d);
mjtNum* qfrc = mjSTACKALLOC(d, nv, mjtNum);
@@ -1047,16 +1047,16 @@ void mj_implicitSkip(const mjModel* m, mjData* d, int skipfactor) {
mju_addScl(MhB, d->qM, MhB, -m->opt.timestep, nM);
// gather qH <- MhB (legacy to CSR)
mju_gather(d->qH, MhB, d->mapM2M, nM);
mju_gather(d->qH, MhB, d->mapM2C, nC);
// factorize in-place
mj_factorI(d->qH, d->qHDiagInv, nv, d->M_rownnz, d->M_rowadr, m->dof_simplenum, d->M_colind);
mj_factorI(d->qH, d->qHDiagInv, nv, d->C_rownnz, d->C_rowadr, m->dof_simplenum, d->C_colind);
}
// solve for qacc: (qM - dt*qDeriv) * qacc = qfrc
mju_copy(qacc, qfrc, nv);
mj_solveLD(qacc, d->qH, d->qHDiagInv, nv, 1,
d->M_rownnz, d->M_rowadr, m->dof_simplenum, d->M_colind);
d->C_rownnz, d->C_rowadr, m->dof_simplenum, d->C_colind);
} else {
mjERROR("integrator must be implicit or implicitfast");