255368 2023-04-12 15:14:18 -0700 Bring slerp interpolation in line with spec 2023-10-12 18:36:47 -0700 1 1 1 Unclassified WebKit Animations WebKit Nightly Build Unspecified Unspecified RESOLVED CONFIGURATION CHANGED InRadar P2 Normal --- 250970 1 ahmad.saleem792 webkit-unassigned dino graouts graouts mattwoodrow webkit-bug-importer oldest_to_newest 1948345 0 ahmad.saleem792 2023-04-12 15:14:18 -0700 Hi Team, Based on discussion with @graouts on Slack 1-1, I am creating this bug report about potential Blink commit merge: Commit - https://chromium.googlesource.com/chromium/blink/+/f550639338aaaa3abf07b88997609a396fb5cfad Spec Discussion Link - http://lists.w3.org/Archives/Public/www-style/2013May/0131.html ``` Commit Message ``` The slerp function to interpolate between two quaternions (when blending two decomposed matrices) does not match the spec. Although it may be desirable for the interpolation to occur along the shortest path (as discussed in issue 14983004 and http://lists.w3.org/Archives/Public/www-style/2013May/0131.html), the spec has not been changed as requested there. So this updates the WebKit implementation to be in line with the spec. ______________________ Just wanted to raise for any input and also it is possible to do 1-1 merge, I did it in local testing branch few weeks back. Thanks! 1948348 1 ahmad.saleem792 2023-04-12 15:21:46 -0700 Blink regressed this: Safari was doing correctly due to relying on system for doing animations (but if we are planning to change, we might have same bug): After this change, will Blink match Safari? If not, Safari can't change its behavior since it relies on the operation system to do animations... ___________________ Test Case mentioned in the Spec Discussion - https://jsfiddle.net/bpLx7gtq/show _____________________ Blink regressed it here (as per documentation): I think so, yes. We got the "bad" behavior when we switched from WebCore::TransformationMatrix to gfx::Transform, according to <https://code.google.com/p/chromium/issues/detail?id=236018>. A quick test in Safari with the example code in my first post has it doing the short-path animation. _________ Another test case - https://jsfiddle.net/f2hxo9k6/ 1949870 2 webkit-bug-importer 2023-04-19 15:15:20 -0700 <rdar://problem/108283899> 1982526 3 ahmad.saleem792 2023-10-04 12:23:21 -0700 This might be Not Applicable after Matt's changes and moving this function (slerp) to 'Quaternion.cpp' here: https://github.com/WebKit/WebKit/blob/53dd791f052cd7ee77e99c492a0b480166fb12b0/Source/WebCore/platform/graphics/transforms/Quaternion.cpp#L36 @Matt - can we close this? 1984790 4 mattwoodrow 2023-10-12 18:36:47 -0700 I think we can close this, we should indeed have the changes already.