"is touching" reporting false negatives on tiny tests

Expected Behavior

is touching tests should not depend on the size of the objects in question or the size of the stage

Actual Behavior

This project behaves differently on staging vs production:

• Production: scratch.mit.edu/projects/445335326
• Staging: 1300006793

As of this test, the two environments differ only by these two changes:

• LLK/scratch-render#557
• LLK/scratch-render#624

Steps to Reproduce

1. Load the project
2. Use WASD to move the cat onto & off of the purple dot
3. The cat should report “true” when overlapping the dot, and “false” when not

Actual behavior:

• in some cases on staging, the cat always reports “false”
• switching to full-screen stage and back may fix the issue
• the issue might depend on whether Scratch is running on a high-DPI screen or not

Operating System and Browser

Seems to affect multiple browsers but Windows Chrome is the most-confirmed case so far.

[fsih]

The not touching project on scratch.mit.edu: The touching project on scratch.ly:

[cwillisf]

Yeah - it seems possible that we have another bug in here related to costumes’ bounds being slightly different on initial save vs. import & save again. Maybe the fix-up code that we run on import can cause small errors like this.