FPS drops about 10 frames after using DisplayList and DisplayGroup about layers

[ivanpopelyshev]

It depends on number of elements that has displayGroup, and whether you sort them. If you have 10k elements i suggest you to learn how pixi updateTransform() works and think how can you optimize it for your case.

pixi-display is the best "runtime" solution, and of course you can make better only if you know "static" optimizations for certain game that dont calculate everything on every frame.

1. Walk through all elements and determine which elements belong to which groups. That's a linear time algorithm, it has the same price that you are paying pixi for walks like "updateTransform" or "renderWebGL" (without cost of rendering itself).

• cheap, but 10k elements on slow computers will screw it. Optimize only if you know how to get rid of pixi updateTransform() too.

2. Z-index sorting for groups: suppose we have a container with 1002 elements, two of them have different behaviour - one if in front and one is in back. If you just assign a "z-index" to all of them, you'll have to sort them all every frame. But with pixi-display you can assign them three different groups: one for back, one for front, and one for everything else, and thus the sort will work only on 3 elements

• that is cheap, most of developers dont think about that approach, that's our gem :)

3. Z-order sorting inside a group: when you have 1000 elements on different distance from screen, put that distance into zOrder field and enable sorting in the group.

• that sort is slow, its the same sort as in phaserjs. First candidate for optimizations.

Currently I have custom "display" solution for 10k elements that uses CPU only when it needs to re-sort something. I will publish it later.

btw, there's new version: https://github.com/pixijs/pixi-display/tree/layers , it has different API , its easier to understand and it allows to use filters/masks: https://pixijs.github.io/examples/#/layers/lighting.js

[ivanpopelyshev]

I re-open it because that's the best explanation i gave so far :)