Effect Depends on Camera

[david van brink]

My effect uses the "current camera" (if any) to determine its behavior, partially. (It does some mock-3d xforms for a 2d backdrop).

I got it to find the correct layerH and ask for the various stream values like rotateX and such.

But when I move the camera, my effect doesn't know to redraw. It caches some image based on the last camera position for that time.

I gather that PF_OutFlag_NON_PARAM_VARY is exactly to address this problem, but I can't quite figure out where and when to set it...

Any guidance appreciated!

[Bruce Bullis]

You'll need a layer param, set to the current camera. That way, AE knows your effect is dependent upon the camera layer, and will invalidate your results (forcing a redraw) when the camera layer changes.

See Checkout for an example of an effect with a layer parameter.

[david van brink]

Hi Bruce --

Thanks for the reply...
but I must ask further.

I can add a layer param, no problem. And thats a nice unambiguous solution (as long as you choose a camera layer and not some other kind)

But what I'd *rather* have is the effect respond to the parameters of the "current camera view". (Even if there's no actual camera layer, or if there are several coming in and out over the duration of the comp.)

I know some effects vary over time (like particle effects, for example). (And yes, I know: "Integrate from t=0!")

How does such an effect know to redraw each frame, even though no parameters have changed?

[Bruce Bullis]

Wow, a documentation reader! ;)

There's always an active camera, even if there's no camera layer; see the Resizer sample, and let me know how it goes.

[david van brink]

Thanks! That did it -- the trick was to use outflags_2.

Is it still true that these values *must* be set in both the pipl and the global setup?

[Bruce Bullis]

Yes.