fix: confetti disappearing in device_preview

[nivivon]

Why

I was working on integrating confetti into an app with device_preview. Currently, it seems that it doesn't show confetti in the right place. This seems to be a position issue.

The confetti layer was using two different ways to measure "where a particle is": local positions and global screen position. They don't match when the app is drawn in a special container (for example, device_preview), so the engine thought every particle was already off-screen and removed it right away. Culling is now done in the same local space the particles are drawn in, and the old global-position path was removed because it’s no longer needed.

Here's a video that showcases the bug:

confetti.bug.mov

I know the last commit is from Sep 28, 2024, which means this may not be reviewed. That said, leaving this just in case anyone runs into the issue. 😄

How I Tested

Add device_preview.

• With device_preview turned off, see the confetti. Resize the window, and see that confetti still shoots out of the right place.

after.fix.-.web.mov

• Using device_preview, see the confetti. Resize the window, and see that confetti still shoots out of the right place.

after.fix.-.mobile.mov

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