Class LoopConstraintBase

• Defined in File LoopConstraintBase.h

Nested Relationships

Nested Types

• Struct LoopConstraintBase::QMats

Inheritance Relationships

Base Type

• public Karana::Dynamics::BilateralConstraintBase (Class BilateralConstraintBase)

Derived Types

• public Karana::Dynamics::LoopConstraintConVel (Class LoopConstraintConVel)

• public Karana::Dynamics::LoopConstraintHinge (Class LoopConstraintHinge)

Class Documentation

class LoopConstraintBase : public Karana::Dynamics::BilateralConstraintBase

Base class for loop constraints See the.

Bilateral closure constraints section for more discussion on loop consttaints.

Subclassed by Karana::Dynamics::LoopConstraintConVel, Karana::Dynamics::LoopConstraintHinge

Public Functions

LoopConstraintBase(kc::ks_ptr<Multibody> &mb, kc::ks_ptr<kf::Frame2Frame> constrainet_f2f, const std::string &name)

Constructor.

inline kc::ks_ptr<kf::Frame2Frame> constraintFrame2Frame() const

Return the Karana::Frame::Frame2Frame whose oframe/pframe define the constraint.

When the constraint is satisfied, the relative configuration, velocity and accel values across the Karana::Frame::Frame2Frame f2f are constrained to those satisfied by the associated constraint hinge

Returns:

the constraint Frame2Frame instance

inline virtual bool hasHinge() const

Return true if the loop constraint is based on a hinge.

Returns:

true if the loop constraint is based on a hinge

inline virtual bool constrainsQ() const

Return true if the loop constraint constrains Q configuration coordinates.

Returns:

true if the loop constraint constrains the Q coordinates

inline kc::ks_ptr<ConstraintNode> sourceNode() const

Return the source (oframe) node for the constraint.

Return the source frame as a constraint node, if the source frame is attatched to a non-virtual root body. Return a null pointer if the source frame is not attached to a multibody body.

Returns:

the source constraint node.

inline kc::ks_ptr<ConstraintNode> targetNode() const

Return the target (pframe) node for the constraint.

Return the target frame as a constraint node, if the target frame is attatched to a non-virtual root body. Return a null pointer if the target frame is not attached to a multibody body.

Returns:

the source constraint node.

inline const QMats &getQMats() const

Return the constraint QMat matrices for this constraint

Protected Functions

virtual km::Vec _accelResidual() const = 0

Return the (6-nU) size accel residual term for the constraint.

Used for computing the lambda (Lagrnage multiplier) terms for the TA dynamics correction step

Returns:

The acceleraton residual eror

km::Vec baumgarteResidual(double stiffness, double damping) const

Return the (6-nU) size Baumgarte residual term for the constraint for use for computing the lambda (Lagrnage multiplier) terms for the Baumgarte dynamics method

void lambda2ConstraintForces(const km::Vec &lambda) const

Convert the lambda Lagrange multiplier term for the constraint into constraint forces at its constraint nodes

void _discard(kc::ks_ptr<Base> &base) override

Discard the provided LoopConstraintBase.

Parameters:

base – - Base pointer to the LoopConstraintBase to discard.

virtual void _computeQMats(QMats &val) = 0

Protected Attributes

kc::ks_ptr<kf::Frame2Frame> _constraint_f2f

the defining Karana::Frame::Frame2Frame for this constraint. The only motion allowed across this f2f is that permitted by the QMat constraint matrices across this f2f.

kc::ks_ptr<ConstraintNode> _source_node = nullptr

the constraint node of the physical body the source frame is attached to. if null, the source frame is not attached to a body

kc::ks_ptr<ConstraintNode> _target_node = nullptr

the constraint node of the physical body the target frame is attached to. if null, the target frame is not attached to a body

kc::ks_ptr<kc::DataCache<QMats>> _QMats_cache = nullptr

cache for computing the nResiduals()x6 the Q relaated orthogonal complement matrices for the constraint hinge coordinate matrix.

struct QMats

Struct for the constraint QMat matrices needed for Gamma and TA dynamics algorithm. The constraint requirement is that.

[sourceQ, targetQ] * [V_source \\ V_target] = 0

where V_source and V_target are the spatial velocities of the source and target frames respectively defined by teh constraint Karana::Frame::Frame2Frame f2f’s oframe/pframe pair.

Public Functions

inline void resize(size_t nC)

Resize the constraint matrices.

Parameters:

The – number of constrained dofs.

Public Members

km::Mat sourceQ

Q at the source frame.

km::Mat targetQ

Q at the target frame.