Apple Motion 3 User Manual
Page 1048
1048
Chapter 12
Using Shapes and Masks
 Play Frames: A checkbox that controls playback. If the checkbox is selected, it loops
the playback of the animation or movie clip. If it’s turned off, the paint dabs use the
still frame specified by either the Random Start Frame parameter or the Source Start
Frame parameter.
 Random Start Frame: A checkbox that introduces variation using QuickTime objects
as the dabs’ source objects. If the checkbox is selected, each dab begins at a different
frame of the animation. Stills are chosen randomly if the Play Frames checkbox is
deselected.
 Source Start Frame: This mini-curve editor allows you to define the frame at which
playback of the source clip begins in the paint dabs. The Source Start Frame default
keyframe value is 0, at which playback starts from frame 1. You can simply change
the start frame for all dabs, or you can create a curve so that start frames vary over
the length of the stroke (different dabs use different start frames). For example, if the
first Source Start Frame value is 50, each dab begins playback at frame 50. If you
create an animation curve that begins at 50 and ends at 250, each dab begins clip
playback at a progressively later frame.
The Play Frames checkbox must be selected in order for playback to occur. If Play
Frames is turned off, you can display different still frames over the length of the
stroke. This parameter only appears if Random Start Frame is turned off.
Note: For information on using the mini-curve editors, see “
 Source Start Frame: Use the sliders or enter a number into the value fields to
change the value of the selected keyframe.
 Stroke Length: Stroke Length is mapped horizontally on the mini-curve editor
graph and provides a visual representation of the position of the changes in start
frame value (keyframes) over the length of the stroke. Use the sliders or enter a
number into the value field to change the value of the selected keyframe.
 Hold Frames: Sets the number of times each frame of the source movie is repeated
during playback. The larger the Hold Frames value, the slower your playback.
 Hold Frames Randomness: Varies the number of frames to “hold.”
Note: Although you can drag a particle emitter, replicator, or a group that contains an
emitter or replicator into the Brush Source well, keep in mind that your project
interactivity will slow drastically.