Can expensive rendering be separated into its own "Layer"?

[Minimog]

I am working on a game view that has overlay modal with scrollable container (Parent container with mask and content container with y transforms on scroll).
In general everything works fine, but I notice my phone heating up sometimes when scrolling this view for a while. I am not using any expensive things like antialiasing, however my stage devicePixelRatio is set at 3 (for iphone xs display).

I assume that with every scroll my whole view is being re-rendered, hence causing this heating up? I was wondering if pixi has a mechanism to separate this scroll container onto a separate layer of some sort and not re-render anything else?

The only solution I can come up with atm is to use second pixi stage on a separate canvas perhaps, but wanted to check here first just in case there is a more elegant solution.

[ivan.popelyshev]

yes. but there's no special thing that tracks whether that layer was changed and has to be recalculated. 

there's only middle-level stuff: renderTextures, filters. I made automatical caching for filtered/scrolled/masked containers in my app, but it took A LOT of me. its really hard to track all changes without performance loss or bugs

Edited November 15, 2020 by ivan.popelyshev

[Minimog]

I see, can I ask how you skip recalculation / render on on your elements when you determine that they are not needed?  I assume you mark each element as either dirty or not and based in that flag do something to either re-render them or skip?

[Exca]

You have basically two options.

1. Render the expensive stuff into a separate rendertexture and use that as you would any other sprite. Rerender the rt when things change.

2. Use two canvases. Update the expensive canvas only when needed.

[Edit] For 1 you can use cacheAsBitmap = true to create rt of a container and use that instead of the whole render list. Though I'd suggest using a custom handling with own RT to handle this as debugging cacheAsBitmap can be a nightmare if there's some errors.

Edited November 16, 2020 by Exca