1630441 - [css-transforms] Zero value in perspective() function

Status: RESOLVED DUPLICATE of bug 1717161

(Core :: Layout, defect, P3)

Description

[Mozilla Apprentice]

A resolution was made for csswg-drafts/#413.

[css-transforms] Zero value in perspective() function

• RESOLVED: 0 is allowed with 1px being the render time clamp

Discussion.

Comment 1

[Daniel Holbert [:dholbert]]

This is a followup to bug 1316236, basically.

Most of the CSSWG discussion on this is here:
https://github.com/w3c/csswg-drafts/issues/413#issuecomment-537729118

Though also see subsequent comments, and note that the issue was reopened...

Comment 2

[Daniel Holbert [:dholbert]]

The spec was changed to reflect this clamping, though.

perspective css property:
https://drafts.csswg.org/css-transforms-2/#perspective-property

...values less than 1px must be treated as 1px for rendering purposes. (This clamping does not affect the underlying value, so perspective: 0; in a stylesheet will still serialize back as 0.)

perspective() function in transform property:
https://drafts.csswg.org/css-transforms-2/#funcdef-perspective

If the depth value is less than 1px, it must be treated as 1px for the purpose of rendering.

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

I should add that Chromium successfully shipped these spec changes. For more details see:
https://bugs.chromium.org/p/chromium/issues/detail?id=1205161
https://chromium.googlesource.com/chromium/src/+/50b1cc46560ac75003b6c64db76fc14d23508735
https://groups.google.com/a/chromium.org/g/blink-dev/c/Up0ruPbddro/m/7J-f9pqiAQAJ

I think most of the sites reported as broken have been fixed (in many cases the reports were from the site developers):
https://bugs.chromium.org/p/chromium/issues/list?q=label%3Aperspective-zero-regression&can=1

Comment 4

[BugBot [:suhaib / :marco/ :calixte]]

The severity field for this bug is relatively low, S3. However, the bug has 5 See Also bugs.
:dholbert, could you consider increasing the bug severity?

For more information, please visit auto_nag documentation.

Comment 5

[Emilio Cobos Álvarez (:emilio)]

Matt fixed this a while ago in bug 1717161, or are we missing something?

Comment 6

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

That's just one piece of it... but I think Matt made some other changes as well, now that I'm remembering.

(I was commenting because I found an item on my to-do list to comment in relevant WebKit and Gecko bugs once we were sure the Chromium changes would not get reverted. And it took me a while to remember to do that...)

Based on a glance at https://wpt.fyi/results/css/css-transforms?label=master&label=stable I think there's nothing left to do here.

Comment 7

[Daniel Holbert [:dholbert]]

Thanks! Let's just dupe to bug 1717161 then (with an implicit-dupe/dependency on the other pieces / other associated changes that got us to the current WPT pass status).