Why is input checkout needed before output checkout?

[spiegelball]

The attached error appears if I try to checkout the output layer before calling checkout_layer_pixels on an input layer. This is consistent with the documentation (https://ae-plugins.docsforadobe.dev/smartfx/smartfx.html?highlight=checkout_output#pf-smartrenderext...). However there are cases where I don't want to check out any inputs and write to the output world immediately (cached render results for example). Why is the checkout needed? 

Additionally, the wording is misleading. Not a layer checkout (checkout_layer) is needed, but a checkout of the layer pixels (checkout_layer_pixels).

[James Whiffin]

Since you don't need an input, are you able to communicate that to AE in smart prerender by requesting a tiny 1x1 rect? I believe if you request an empty rect it will give you the entire input. 

[spiegelball]

The problem is, sometimes I can only discover that during SmartRender. Whilst I appreciate your idea I'd like to understand the fundamental concept for this requirement from the AE side.

[shachar carmi]

yeah, this is kind of an optimization blindspot in the SDK.

some plug-ins don't need an input. for example fractal noise, particle world, ect... alas, in the current AE workflow the input must be checked out.

why must it be checked out BEFORE checking out the output? as to enforce a situation where you might release the input before checking out the output, thus not occupying memory for both input and output at the same time. but again, this scheme missed the scenrio where the input is not required at all.

[spiegelball]

Ahh, I see! Thank you for the explanation. If this requirement would go, I'd be happy!