Scratch

Hi,

I'm trying to create a set of "cartoon" blocks in BYOB to help students manage animations.  The idea is to hide the logic for interrupting animations, so that students only have to invoke a new animation in order to kill the existing one.

The code below is invoked from a script that controls the movement of a car by polling the keyboard.  Triggering a new "loop" animation automatically terminates any other animation(s) that may be running.

(Just discovered I can't post images as a new member, so here is the URL:

http://www.newlifeinteractive.com/images/Usage.jpg

This works... but most of the time a good second or two elapses before the animations switch, and sometimes two animations get stuck playing at once.

I'm using "atomic" blocks to do the flag-setting necessary to signal a switch in cartoons, to avoid race conditions; however, the behavior I'm seeing indicates that this code sequence is running in parallel with other invocations of itself, leading to what appear to be race conditions when keys are pressed and released quickly.

I've tried the "thread safe" and "turbo" settings in BYOB without any effect.

I'll show the relevant code for the looping cartoon block.  Many thanks in advance to anyone who has a suggestion on how to make this work.  My next approach will be to have a single cartoon framelist per sprite, which gets swapped out directly, and a single frame-switching loop per sprite, so that there will be no possibility of a conflict.  However, this starts to expose the internals of the logic, which defeats my original purpose for creating these blocks.

In any case, here is the "loop cartoon" block.  The first thing it does is call an "atomic" block (GB INTERNAL CARTOON LAUNCH) to switch off any currently running animatons.  You can see by the way this block terminates its own loop how the interrupt signal is communicated between scripts.

http://www.newlifeinteractive.com/images/LoopBlock.jpg

And here is the implementation of the cryptic "internal launch" block:

http://www.newlifeinteractive.com/images/InternalLaunchBlock.jpg

(The insertion of the new "thread" record at the *beginning* of the list was just an odd experiment.)

And finally the (also atomic) "stop cartoons" block, which does the actual update to the data structure.

http://www.newlifeinteractive.com/images/StopCartoonsBlock.jpg

Any idea why the latter two blocks don't execute in one "call"?  Are there any workarounds?  Am I misunderstanding something? 

Thanks,
alloplastic