After adding pen extension, rendering results are different

[Ryuurock]

Expected Behavior

Adding pen extensions should not affect rendering results

Actual Behavior

Rendering results are affected after adding pen extension

Steps to Reproduce

1. Load the provided sb3 file
2. Click the green flag
3. The face on the left will move up
4. Add pen extension
5. Reload the provided sb3 file，Click the green flag
6. The face on the left will not move up

Operating System and Browser

_e.g. Mac OS 10.15.6 Chrome 80.0.3987.163

jump.zip
Please modify the file suffix to .sb3

Below is the animation I recorded
👇before load pen extension

👇after load pen extension

[Ryuurock]

After investigation, it is found that it may be the problem caused here
scratch-vm/src/extensions/scratch3_pen/index.js

[BryceLTaylor]

@Ryuurock I'm unable to reproduce this issue with that project. Are there more steps you take while adding the pen extension, such as adding any blocks to the project? Can you cause this issue to happen on a simpler project?

[Ryuurock]

@BryceLTaylor Ok，I made some fixes

1. Load the provided sb3 file, Click the green flag
2. Check the stage, The face on the left will move up

Then reload scratch.

1. First, add pen extension
2. Load the provided sb3 file，Click the green flag
3. The face on the left will not move up

[BryceLTaylor]

Okay, so to see it you have to load it by doing File>Load from your computer, not reloading the page. It also seems to only happen with the pen extension (that I've tested so far.). It did not happen with the Music or the Makey Makey extension.

@Ryuurock Can you make a simplified version of the project that has only the minimum number of sprites and scripts to see this issue? I'd like to get some repro steps for how to create a project that exhibits this issue.

[Ryuurock]

simplified_version.zip
@BryceLTaylor simplified version

It looks like the result after adding the pen extension is correct

[BryceLTaylor]

@Ryuurock thanks! That's super helpful.

[adroitwhiz]

This looks like it has something to do with scratchfoundation/scratch-render#488. The sprite is testing whether it's touching the color black, but the transparent backdrop seems to be confusing it. If I test this on my "touching white fixes" branch, it works properly.

[cwillisf]

Current status: we hope this will be fixed by scratchfoundation/scratch-render#676, which is still in progress

[cwillisf]

This appears to be fixed now, probably by scratchfoundation/scratch-render#686