Effect depends on Position, Rotation, Scale of the Layer

this solution is a bit shady, but it will do the job.
add another parameter, say, a slider.
using AEGP_setExpression apply to that slider an expression like this:
"position[0] + scale[0] + rotation + anchorPoint[0]"
then, using AEGP_dynamicStreaSuite, make that slider invisible.

so what to you get?
you get a parameter that the user is unaware of, that calls for your plug-in to render automatically whenever the user changes the position, rotation, scale or anchor point.

I hope it helps you,
it worked for me.
:-)

You can't; there's no method for effects to identify such dependencies.

Hello Brooce,

If the effect params do not change, would it be possible to redraw when only the layer properties change?

Your solution above mentions that we can use parameter supervision to get a callback into the effect plugin.
But I only know how to set supervision for effect params, how can we do this for the layer that the effect is applied to?

Thanks!
Chia

Hi brooce, Thanks for the tips. I'll try it and hopefully it'll work.

AE doesn't have a method for effects to identify such dependencies. Your best bet is to use parameter supervision (see the Supervisor sample), and check the xform values during PF_Cmd_FRAME_SETUP. If the values your plug-in was using are now stale, save the fresh values, and cancel out of the render. You'll be called to render again, with your fresh values.

Setting a bunch of breakpoints in a debugger will teach you more about param supervision than reading ever will. :)