What is 'Round to Pixels' means

[HoangDuyTran]

In this page:

https://docs.blender.org/manual/en/dev/modeling/meshes/uv/editing.html

There is this block of text:

Round to Pixels

During UV transforms, you can use Round to Pixels to help with matching features in the image or ensure your UVs have precise horizontal, vertical or diagonal alignment.

Note that Round to Pixels is applied after any snapping modes.

Disabled

UVs will not be rounded.

Corner

Will force the UVs to round to the corner of the nearest pixel of an image if loaded.

Center

Will force the UVs to round to the center of the nearest pixel of an image if loaded.

and though I found the original developer’s note here:

Grid & Pixel snapping in the UV editor

I still don’t really understand the meaning of ‘Rounding UVs’ to Pixels means. Originally it was ‘Snap’ which is more intuitive to me, but I’m not the developer and hence cannot visualise the differences between ‘snapping’ and ‘rounding’ the UVs. Can someone familiar with the subject please enlighten me?

Best regards,

[Okidoki]

Hmm… … this seems to be a bit unfortunate… if in the UV-Editor → View → Pixel Coordinates are set to pixels then they are not displayed as float between 0.0. and 1.0 but additionally with some digits after the floting point… so if you want to Snap them to the Pixels the are just rounded to be simple integer…

I think that’s the meaning behind the comment:

Rename “Snap to Pixels” to “Rounds to Pixels” (or another names that avoids the term “Snap”) this is a post-process when transforming, it’s not applied as part of the snapping.

(And also further done th dev-thread.)

So they want to distinguish between snapping to grid (with the usual magnet icon: Snap → Snap UV during transform. ) and snapping to pixels ( UV-> Snap to Pixels ).
Maybe they shout just grey out the later if not set to pixels coordinates… but then users will ask why it is greyed oout because they didn’t found the Pixel Cordinates / UV coordinates swtich…

Or maybe call this just Pixelsnapping… but as said they discuss this in the dev thread… even saying

When there’s further improvements to the snapping requested, we’ll open a new task based on the current working behavior.

( too bad sometimes in those dev disccussion systems this new tasks isn’t easy to find… )

[HoangDuyTran]

I can see what it is trying to do, such as this

This is round to center of the pixel:

and this is round to corner:

But I don’t see the meaning of the word ‘Round’. How do you view the coordinates of the pixels ?

I turned it on here and cannot see the numbers you’re describing:

[HoangDuyTran]

I finally saw what you mean in terms of rounding:

This is floating point number, set with ‘.50’ meaning half,

This is with integer number, no floating point at the end,

[Okidoki]

Yepp you got it.