How do I move, rotate, or scale a layer over time?

[Guest]

Hey Folks,

I'm writing my first AE Plugin, and I want to start with something simple. I just want to move, rotate, or scale a layer based on the current composition time. It sounds easy, but after reading all of the documentation, and looking at most of the samples, I can't figure out this simple task.

I would basically like to implement something similar to the the built-in presets "Rotate Over Time" or "Wiggle - scale".

Can you give me any pointers on how to do this? Do you know of any samples that shows how to modify layer properties? At this point I'm not even sure whether this should be an Effect, an AEGP, or something else.

Thanks so much for your help,

James

[françois leroy]

Hi James,

if you want to actually move the layer itself, and so probably keyframe its geometry, then you have to write an AEGP (or even a script, which is easier...).

Now you can also write a layer Effect that will mimic these transformations, like the 'Transform' effect does. In this case, look for 'PF_WORLDTRANSFORMSUITE1' in the SDK. The 'Transform_world()' function uses a matrix (or 2 if you handle motion blur) to rotate, scale, move your PF_EffectWorld.

Hope it helps you start.

François