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468 Chapter 5 Using Behaviors
The angle at which the object bounces depends on the angle at which it hits the edge
of the frame; the speed it travels after bouncing is set by the Bounce Strength
parameter.
Note: Edge Collision has no effect on objects that are larger than the Canvas.
Important: By default, the Edge Collision behavior uses the size of the project and the
bounding box to determine how the object collides with the edge of the Canvas. For
example, in an NTSC Broadcast SD project (720 x 486 pixels), an object bounces off the
right and left edges of the project at its bounding box. With groups (particles, text, and
objects), only the object’s center is used. You can make the object travel further off the
Canvas before it bounces by adjusting the Width and Height parameters. If you’re using
this behavior with an object that has an alpha channel that’s smaller than its bounding
box, adjust the Crop parameter in the object’s Properties tab to fit the bounding box as
closely as possible to the edge of the image.
HUD Control
The HUD has controls for Bounce Strength and Width, Height, and Depth. When
applied to an object that contains multiple objects (such as a group, particles, text, or
the replicator), the Affect Subobjects checkbox also appears in the HUD.
Parameters in the Inspector
Affect Subobjects: This parameter appears when this behavior is applied to an object
that contains multiple objects, such as a group, a particle emitter, a replicator, or a text
layer. When this checkbox is turned on, all objects within the parent object are affected
individually. When this checkbox is turned off, all objects within the parent object are
affected by the behavior together, as if they were a single object.
Bounce Strength: The speed at which objects travel after colliding with an edge. A
value of 0 causes objects to come to a complete stop when colliding with an edge
that’s perpendicular to the direction of motion. Higher values cause an object to move
faster after bouncing. This parameter only slows the object in the direction
perpendicular to the bounced edge.
Active Edges: Six checkboxes define which collision box edges are detected by the
Edge Collision behavior. You can turn edges on and off in any combination.
Left Face: Defines the left edge for the collision.
Right Face: Defines the right edge for the collision.
Top Face: Defines the top edge for the collision.
Bottom Face: Defines the bottom edge for the collision.
Back Face: Defines the back edge (in Z space) for the collision.
Front Face: Defines the front edge (in Z space) for the collision.