Fix the DisplayObject#cacheAsBitmap issue #5784

[mofnire]

Description of change

This PR is to fix #5784. There are two problems in DisplayObject#_initCachedDisplayObject.

1. The first one is renderer._activeRenderTarget does not hold a current rendering target.

https://github.com/pixijs/pixi.js/blob/4d71fa06ea787d81651fc3e624610ccfc3c3f457/packages/mixin-cache-as-bitmap/src/index.js#L185-L189

I replaced it with const cachedRenderTarget = renderer.renderTexture.current;.

2. The second one is renderer.projection.transform is not restored after the line 213.
   I changed the method so that the projection transform is restored.

https://github.com/pixijs/pixi.js/blob/4d71fa06ea787d81651fc3e624610ccfc3c3f457/packages/mixin-cache-as-bitmap/src/index.js#L210-L216

Working example is https://www.pixiplayground.com/#/edit/hk1gjmUM84Nl72GncOii~.

*Please note I could not find the way of writing tests of features like this :( *

Pre-Merge Checklist

• Tests and/or benchmarks are included
• Lint process passed (npm run lint)
• Tests passed (npm run test)

[codecov-io]

Codecov Report

Merging #5841 into dev will decrease coverage by 0.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##              dev    #5841      +/-   ##
==========================================
- Coverage   70.55%   70.54%   -0.02%     
==========================================
  Files         205      205              
  Lines       10400    10402       +2     
==========================================
  Hits         7338     7338              
- Misses       3062     3064       +2

Impacted Files	Coverage Δ
packages/mixin-cache-as-bitmap/src/index.js	53.04% <0%> (-0.66%)	⬇️

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[bigtimebuddy]

Thanks for the demo to help verify. You’re on a roll @mofnire!

[ivanpopelyshev]

OK, i know how to fix that, good catch! The idea is to store renderer.renderTexture.sourceFrame , not projection.transform.

That's how we generally bind renderTexture: renderer.renderTexture.bind(rt); That's how its fone in FilterSystem: renderer.renderTexture.bind(rt, sourceFrame);

Third param, destinationFrame, is never actually used in tree-related operations, I'll mark that parameter as wont be restored after temporary bind

I'll do separate PR and use your example to test it.

[ivanpopelyshev]

Nope, you are completely right, we need exactly those lines to solve that issue. I dug up another one, but sourceFrame doesn't save it, so i'll form my PR separate from yours after we merge your fix.

Cursed playground: https://www.pixiplayground.com/#/edit/62HZx5glfSl7R1TJe_5aH

[stevenalanstark]

Thank you very much for this, well done! :D