A rigid body is a body that is simulated by rigid body dynamics. The body has a Shape that is constant for the simulation (although the shape can be exchanged by the user). No deformations are computed, therefore this body cannot model a soft body like cloth or fluids.

The body also has a mass properties defined in MassFrame and a Material that defines friction, bounciness and other material properties.

Center Of Mass: The body has a Pose that defines its position and orientation in world space. The origin of the local space of the body can be different from its center of mass. The body has a PoseCenterOfMass that defines the pose of the center of mass in world space. The center of mass is automatically computed from the shape of the rigid body when the body's MassFrame is created. To move the rigid body to a new pose the properties Pose or PoseCenterOfMass can be used; the two properties are synchronized automatically.

Collision Detection: The rigid body class implements IGeometricObject and it automatically creates a CollisionObject for the rigid body. This collision object is automatically added to the CollisionDomain of the simulation.

Important: An IGeometricObject instance registers event handlers for the Changed event of the contained Shape. Therefore, a Shape will have an indirect reference to the IGeometricObject. This is no problem if the geometric object exclusively owns the shape. However, this could lead to problems ("life extension bugs" a.k.a. "memory leaks") when multiple geometric objects share the same shape: One geometric object is no longer used but it cannot be collected by the garbage collector because the shape still holds a reference to the object.

Therefore, when Shapes are shared between multiple IGeometricObjects: Always set the property Shape to Empty when the IGeometricObject is no longer used. Empty is a special immutable shape that never raises any Changed events. Setting Shape to Empty ensures that the internal event handlers are unregistered and the object can be garbage-collected properly.

Cloning: The rigid body can be cloned using the Clone method. Cloning creates a deep copy of the object. The UserData and the Material are copied and not cloned, so the clone will refer to the same UserData and Material instances. All other properties are properly cloned.

Sleeping: See also SleepingSettings. The rigid body automatically wakes up if important properties are changed - for example, if the Shape is changed, the body wakes up.

Reference