[Webkit-unassigned] [Bug 243091] New: filter with primitiveUnits=objectBoundingBox is applied per tile

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=243091

            Bug ID: 243091
           Summary: filter with primitiveUnits=objectBoundingBox is
                    applied per tile
           Product: WebKit
           Version: Safari Technology Preview
          Hardware: Mac (Apple Silicon)
                OS: macOS 12
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: CSS
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: johannes.odland at nrk.no

Created attachment 461131

  --> https://bugs.webkit.org/attachment.cgi?id=461131&action=review

Screenshot of unexpected result in STP

Given an SVG filter that has primitiveUnits set to objectBoundingBox. 
When applying this filter to an element using the CSS filter property, the rendered output is unexpected. 

What seems to happen:

The element is broken along the rendered tiles. 
Each part of the segmented element is assigned coordinates from 0,0 to 1,1, and the filter is applied per segmented element. 

Expected behaviour: 

Length values within the filter should correspond to the whole bounding box of the element, and not to the rendered tile.

"If primitiveUnits is equal to objectBoundingBox, then any length values within the filter definitions represent fractions or percentages of the bounding box on the referencing element"
https://www.w3.org/TR/filter-effects-1/#element-attrdef-filter-primitiveunits

How to reproduce:
The issue is reproduced in the following pen: https://codepen.io/johannesodland/pen/PoRjPJv

It is possible to mitigate the problem by forcing the element to be rendered as a separate layer, using `transform: translateZ(0)` or similar.

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