Adobe Director Basics

ADOBE DIRECTOR BASICS
3D: Controlling action
Every frame, Director generates a series of events that are sent to all sprites and to the first Movie Script that contains
a handler for the event.
#enterFrame: sent after the image of the frame has been displayed on the screen. All sprites and 3D nodes will
report their new positions accurately.
#exitFrame: sent while the current frame is still on the screen, after the Director has registered the new position
of the mouse, but before any adjustments have been made to the position of sprites or 3D nodes
#stepFrame: sent only to scripts and script instances placed on the actorList. See “actorList and #stepFrame events”
on page 426.
#prepareFrame: sent while the current frame is still on the screen but before modifying the positions of sprites and
3D nodes in preparation for displaying the image of the next frame.
Immediately after the #prepareFrame event, Director plays sounds, updates the position of 3D nodes, draws
sprites, and performs any transitions or palette effects. When this is complete #enterFrame is then sent again.
Between the #prepareFrame and the following #enterFrame event, the Director playback engine is calculating the
value of each pixel to display on the screen. Any code that executes during this period increases the time it takes to
display the next screen.
If the movie is playing at 50 frames per second, each frame will be visible on the screen for 20 milliseconds (= 1000 ms
/ 50 frames per second). The Director playback engine will aim to trigger a new #exitFrame event 20 milliseconds
after the previous one.
Between #enterFrame and #exitFrame, the Director playback engine is “idle”. It has time to wait until the next frame
is ready to be drawn. During this time, the playback engine can process a large quantity of code without slowing down
the process of redrawing the screen. It is in the period between #enterFrame and #exitFrame that many other events
are generated. These include:
#mouseEnter, #mouseWithin, #mouseDown, #mouseUp, #mouseLeave, #mouseUpOutside
#keyDown, #keyUp
Callbacks from timeOut objects
Callbacks from 3D #timeMS events
enterFrame
If performance is critical to your project, place any lengthy code that needs to be executed on every frame in an on
enterFrame Lingo handler. This is especially true if the code involves updating the appearance or position of sprites
on the screen.
However, an on enterFrame() handler is not good location for code that deals with moving an item in
synchronization with the mouse. The lag between the moment the operating system updates the position of the mouse
pointer and the moment when Director updates the Stage is most obvious if the Stage updates are made in an on
enterFrame() handler.
exitFrame
The #exitFrame event is sent just before the process for calculating the new Stage image starts. Any code executed as
the result of an #exitFrame event will delay the update process, in the same way that looking for you keys just before
you leave the house delays your departure. Limit your use of your on exitFrame() handlers to navigational calls to
_movie.go() or _movie.play().
Last updated 8/26/2011
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