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[constraint] Add a contactDistance for the ConstraintUnilateral #24

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Merged
epernod merged 1 commit into from
May 29, 2026
Merged

[constraint] Add a contactDistance for the ConstraintUnilateral #24

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13 changes: 13 additions & 0 deletions src/ConstraintGeometry/constraint/ConstraintUnilateral.h
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@ class SOFA_CONSTRAINTGEOMETRY_API ConstraintUnilateral : public TBaseConstraint<
SOFA_CLASS(ConstraintUnilateral , SOFA_TEMPLATE2(TBaseConstraint,collisionalgorithm::BaseProximity,collisionalgorithm::BaseProximity) );

Data<double> d_friction;
Data<double> d_contactDistance;
Data<double> d_maxforce0;
Data<double> d_maxforce1;
Data<double> d_maxforce2;
Expand All @@ -26,11 +27,23 @@ class SOFA_CONSTRAINTGEOMETRY_API ConstraintUnilateral : public TBaseConstraint<

ConstraintUnilateral()
: d_friction(initData(&d_friction, 0.0, "mu", "Friction"))
, d_contactDistance(initData(&d_contactDistance, 0.0, "contactDistance", "Standoff distance kept between the proximities in contact"))
, d_maxforce0(initData(&d_maxforce0, std::numeric_limits<double>::max(), "maxForce0", "Max force applied on the first axis"))
, d_maxforce1(initData(&d_maxforce1, std::numeric_limits<double>::max(), "maxForce1", "Max force applied on the second axis"))
, d_maxforce2(initData(&d_maxforce2, std::numeric_limits<double>::max(), "maxForce2", "Max force applied on the third axis"))
, l_directions(initLink("directions", "link to the default direction")) {}

void getConstraintViolation(const core::ConstraintParams* p,
sofa::linearalgebra::BaseVector* v, unsigned cid) override
{
TBaseConstraint<collisionalgorithm::BaseProximity,collisionalgorithm::BaseProximity>::getConstraintViolation(p, v, cid);
// Shift violation by -contactDistance so that the constraint is maintained at a distance.
// ic->id() is the normal row.
const double cd = d_contactDistance.getValue();
for (const auto& ic : d_container.getValue())
v->add(ic->id(), -cd);
}

ConstraintNormal createConstraintNormal(const BaseProximity::SPtr & first, const BaseProximity::SPtr & second) const override {
if (l_directions==NULL) return ConstraintNormal();

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