Vector costumes become low resolution when scaled beyond stage bounds

[thisandagain]

Expected Behavior

Vector costumes should maintain resolution when scaled.

Actual Behavior

Vector costumes become low / poor resolution when scaled past the stage bounds.

Steps to Reproduce

• Create a new project
• Select "costume2" in the paint editor and scale it up to the bound of the paint editor
• Add the following code (commonly used by Scratchers to create "levels" in games):
  

References

Minimal Repro

https://scratch.mit.edu/projects/274832716
https://llk.github.io/scratch-gui/develop#274832716

Genesis Sonic Engine

https://scratch.mit.edu/projects/74711180/
https://llk.github.io/scratch-gui/develop#74711180

360 Sonic Engine Test

https://scratch.mit.edu/projects/16064469/
https://llk.github.io/scratch-gui/develop#16064469

/cc @ktbee @kchadha @cwillisf

[thisandagain]

May be related to scratchfoundation/scratch-vm#1480

[cwillisf]

I discovered last night that at least 74711180, and maybe the other projects here, run on the 2D renderer in Scratch 2.0; this means there's effectively no texture size limit. By comparison the 2048x2048 limit in Scratch 3.0's renderer is pretty restrictive...

As a test, you can try dragging a set/change effect block out onto the scripting area when running one of these projects. This should cause Scratch 2.0 to switch to its 3D renderer. On 74711180 this causes the terrain to disappear completely, not just get blurry.

I now think the right solution here would be to try to increase the texture size as far as the current video hardware will allow, backing down to a smaller size if texture creation fails. This will cause some projects (the ones affected by this issue) to look different on different video hardware, but should make such projects less blurry where possible.

In the longer term we could look into breaking a large costume into many textures but that could get quite complicated -- not the kind of thing we'd want to hotfix.

[thisandagain]

@cwillisf Thanks for the update! That makes sense. Agree on the short term vs. long term fix for this.

[thisandagain]

@cwillisf Let's use this issue to track the short-term fix (looks like @fsih has a PR in scratchfoundation/scratch-render#391). Do you mind filing a new issue for the long-term fix?