GeneralContactSubsystem Class Reference

This class performs collision detection for use in contact modeling. More...

#include <GeneralContactSubsystem.h>

Inheritance diagram for GeneralContactSubsystem:

List of all members.

Public Member Functions
	GeneralContactSubsystem ()
	GeneralContactSubsystem (MultibodySystem &)
ContactSetIndex	createContactSet ()
	Create a new contact set.
int	getNumContactSets () const
	Get the total number of contact sets that have been created.
void	addBody (ContactSetIndex index, const MobilizedBody &body, const ContactGeometry &geom, Transform transform)
	Add a body to a contact set.
int	getNumBodies (ContactSetIndex set) const
	Get the number of bodies in a contact set.
const MobilizedBody &	getBody (ContactSetIndex set, int index) const
	Get the MobilizedBody in whose reference frame a body is defined.
const ContactGeometry &	getBodyGeometry (ContactSetIndex set, int index) const
	Get the ContactGeometry which defines the shape of a body.
ContactGeometry &	updBodyGeometry (ContactSetIndex set, int index)
	Get a mutable reference to the ContactGeometry which defines the shape of a body.
const Transform &	getBodyTransform (ContactSetIndex set, int index) const
	Get the location and orientation of a body.
Transform &	updBodyTransform (ContactSetIndex set, int index)
	Get a mutable reference to the location and orientation of a body.
const std::vector< Contact > &	getContacts (const State &state, ContactSetIndex set) const
	Get a list of all contacts between bodies in a contact set.
	SimTK_PIMPL_DOWNCAST (GeneralContactSubsystem, Subsystem)

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Detailed Description

This class performs collision detection for use in contact modeling.

It manages sets of bodies that can potentially interact with each other. At each time step, it identifies all the contacts between them. It does not directly affect the behavior of the system in any way. Instead, it simply provides a service that can be used by other classes to implement forces, events, contraints, etc. that are based on contacts between bodies.

To use this class, first create a "contact set" by calling createContactSet(). A contact set is a group of bodies which can interact with each other. If you create multiple contact sets, the bodies within each one will be checked for contacts with each other, but bodies in different sets will not interact.

Next, add bodies to the contact set. Each one is represented by a ContactGeometry object that describes its shape, the MoblizedBody it is attached to, and a Transform giving the location of the geometry in the MobilizedBody's reference frame.

Finally, call getContacts() to get a list of all contacts which exist between bodies in a contact set. Each Contact specifies two bodies that overlap, along with a description of the contact point, such as its location and normal vector.

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Constructor & Destructor Documentation

GeneralContactSubsystem

(

)

GeneralContactSubsystem

(

MultibodySystem &

)

[explicit]

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Member Function Documentation

void addBody	(	ContactSetIndex	index,
		const MobilizedBody &	body,
		const ContactGeometry &	geom,
		Transform	transform
	)

Add a body to a contact set.

Parameters:

	index	the index of the contact set the body should be added to
	body	the MobilizedBody whose reference frame the body is attached to
	geom	a ContactGeometry describing the shape of the body
	transform	the location and orientation of the ContactGeometry in the MobilizedBody's reference frame

ContactSetIndex createContactSet

(

)

Create a new contact set.

The return value is an index which can be used to refer to the contact set when calling other methods.

const MobilizedBody& getBody	(	ContactSetIndex	set,
		int	index
	)			const

Get the MobilizedBody in whose reference frame a body is defined.

Parameters:

	set	the contact set the body belongs to
	index	the index of the body within the contact set

const ContactGeometry& getBodyGeometry	(	ContactSetIndex	set,
		int	index
	)			const

Get the ContactGeometry which defines the shape of a body.

Parameters:

	set	the contact set the body belongs to
	index	the index of the body within the contact set

const Transform& getBodyTransform	(	ContactSetIndex	set,
		int	index
	)			const

Get the location and orientation of a body.

Parameters:

	set	the contact set the body belongs to
	index	the index of the body within the contact set

const std::vector<Contact>& getContacts	(	const State &	state,
		ContactSetIndex	set
	)			const

Get a list of all contacts between bodies in a contact set.

Contacts are calculated at Dynamics stage, so the state must have been realized to at least Dynamics stage. This subsystem is guaranteed to be realized before all ForceSubsystems, however, so a Force may still invoke it to calculate forces based on contacts.

int getNumBodies

(

ContactSetIndex

set

)

const

Get the number of bodies in a contact set.

int getNumContactSets

(

)

const

Get the total number of contact sets that have been created.

SimTK_PIMPL_DOWNCAST	(	GeneralContactSubsystem	,
		Subsystem
	)

ContactGeometry& updBodyGeometry	(	ContactSetIndex	set,
		int	index
	)

Get a mutable reference to the ContactGeometry which defines the shape of a body.

Parameters:

	set	the contact set the body belongs to
	index	the index of the body within the contact set

Transform& updBodyTransform	(	ContactSetIndex	set,
		int	index
	)

Get a mutable reference to the location and orientation of a body.

Parameters:

	set	the contact set the body belongs to
	index	the index of the body within the contact set

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The documentation for this class was generated from the following file:

• GeneralContactSubsystem.h