User Guide

292 APPENDIX E

When positioning a physical model, you are actually specifying the location of its center of mass. This may be

different than the position deﬁ ned for the position of the SceneGroup from which the physical model may have been

made. When ﬁ rst created the physical model will be in the same visual location as the SceneGroup or Viewpoint

object from which it was made. The offset between the physical model and the SceneGroup or ojbect position may

be computed at that time. The importance of the distinction is apparent when using moveTo or transformTo for the

physical model.

It should be noted that for any of the physics based constraints or actions, it is necessary to assign reasonable mass

values when creating the physical models so that physics processing does not become unstable (driven out of scope).

The guidelines for mass and inertia are decribed in the method createPhysicalModel().

If you plan to control the movement of a physical model but want it ﬁ xed for the moment, set a reasonable mass

value when creating it, and also set the ﬁ xed ﬂ ag to true. This will prevent angular and lateral motion, but still enable

collisions. When moving the object, it is preferable to use moveTo / transformTo / rotateTo so that collisions are

properly considered along the move path and ﬁ nal destination.

Properties

type

The object’s type; returns “PhysicalModel”

if (foo.type == ‘PhysicalModel’) { ... }

worldSpacePosition

the position of the object used to create the PhysicalModel, in world space coordinates (as a Vector).

myPhysicalModelCreatorObject.worldSpacePosition = myAnchor3.worldSpacePosition;

worldSpaceOrientation

the rotational orientation of the object used to create the PhysicalModel, in world space coordinates (as a

Rotation). Note that Atmosphere uses the units of Radians for rotations (where a full circle = pi * 2).

myPhysicalModelCreatorObject.worldSpaceOrientation = myAnchor3.worldSpaceOrientation;

worldSpaceTransform

the Transform object (representing the combined position and orientation) of the object used to create the

PhysicalModel, in world space coordinates.

myPhysicalModelCreatorObject.worldSpaceTransform = myAnchor3.worldSpaceTransform;

rigidBodyWorldSpacePosition

the position of the center of mass for the PhysicalModel, in world space coordinates (as a Vector).

myPhysicalModel.rigidBodyWorldSpacePosition = myAnchor3.worldSpacePosition;

rigidBodyWorldSpaceTransform

the Transform (representing the combined position and orientation) of the center of mass for the

PhysicalModel, in world space coordinates.

myPhysicalModel.rigidBodyWorldSpaceTransform = myAnchor3.worldSpaceTransform;