Instruction Manual

Chapter 9 Behaviors 359
Edge Collision
The Edge Collision behavior is ideal for setting up complex motion simulations with objects
that do not exit the Canvas. Objects with the Edge Collision behavior applied come to a stop or
bounce o after colliding with the edge of the Canvas frame. For example, if you apply the Throw
behavior to an object and set the velocity to send the object toward the edge of the frame, then
apply Edge Collision, the object will bounce o the edge of the frame according to the Bounce
Strength parameter. Edge Collision has no eect on objects larger than the Canvas.
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.
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 o 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 o 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 Inspector to t the bounding box as closely as possible to the edge of the image.
Parameters in the Inspector
•
Aect Subobjects: A checkbox, available 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 selected, all objects in the parent object are aected individually. When this
checkbox is deselected, all objects in the parent object are aected by the behavior together.
•
Bounce Strength: A slider that sets 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 that dene which collision box edges are detected by the Edge
Collision behavior. You can turn edges on and o in any combination.
•
Left Face: Denes the left edge for the collision.
•
Right Face: Denes the right edge for the collision.
•
Top Face: Denes the top edge for the collision.
•
Bottom Face: Denes the bottom edge for the collision.
•
Back Face: Denes the back edge (in Z space) for the collision.
•
Front Face: Denes the front edge (in Z space) for the collision.
•
Width: A slider that sets a width (the right and left edges of the Canvas) other than the size of
project. By default, Width is set to the project size.
•
Height: A slider that sets a height (the top and bottom edges) other than the size of project. By
default, Height is set to the project size.
•
Depth: A slider that sets a depth (the back and front faces, in Z space) for the edge collision. By
default, Depth is set to 100 pixels.
67% resize factor