[Webkit-unassigned] [Bug 67695] (animated?) rotate and rotate3d improperly handle values over 180 degrees

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=67695





--- Comment #2 from John Schulz <webkit.org at JFSIII.org>  2011-09-07 10:04:21 PST ---
I'm observing these issues in Safari 5.1 (as well as Chrome stable) on Mac OS 10.6.8. I put notes in the Notes column where the behaviors differ between the two browsers.

Sorry the observed behaviors weren't clear. In short, there are times when values over 180 degrees will cause the animations to misbehave. I tried to detail what was happening via the expected / actual rotation, correct direction, etc columns.

For example, http://jsbin.com/omedam/1/edit#html,live should rotate 540 degrees, but instead it only rotates 180 degrees: http://screencast.com/t/V2rzyADiDqB The direction of the rotation is correct, but the amount is incorrect.

However, in http://jsbin.com/omedam/21/edit#html,live both the direction and the amount of rotation are incorrect. The image should rotate 270 clockwise but, instead, only rotates 90 degrees counterclockwise.  This video shows how a value of 180deg will behave as expected, where a value of 181deg will cause the direction of the animation to change.

There are also examples where transformations which seem to be the same will exhibit different behavior. http://jsbin.com/omedam/2/edit#html,live goes from rotateY(0deg) to rotateY(540deg) and behaves as expected. Where http://jsbin.com/omedam/33/edit#html,live goes from rotate3d(0,1,0,0deg) to rotate3d(0,1,0,540deg) and will only rotate 180 degrees, but in the correct direction.

http://jsbin.com/omedam/2/edit#html,live has an identity function of  rotateY(0deg) and a transform function of rotateY(540deg) and behaves as expected. However, http://jsbin.com/omedam/1/edit#html,live has an identity function of rotate(0deg) and a transform function of rotateY(540deg) and exhibits the 'correct direction but incorrect amount' misbehavior. Perhaps the identity and transform functions must be same but I didn't see that in the spec http://www.w3.org/TR/css3-3d-transforms/. And, even if they should be the same, I think not rotating at all is less confusing than rotating an incorrect amount.

I created multiple pages because there multiple types of misbehavior (wrong direction and/or wrong amount) and multiple functions (rotate, rotateX, rotateY, rotateZ, rotate3d) are affected. I wanted to provide both examples of both success and error conditions in an effort to determine the underlying cause.

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