Bug 366531

Summary:	git master: Transform (qtblend) effect doesn't allow for CCW rotation; rotation origin is top-left instead of center
Product:	[Applications] kdenlive	Reporter:	Wegwerf <wegwerf-1-2-3>
Component:	Video Effects & Transitions	Assignee:	Vincent PINON <vpinon>
Status:	RESOLVED FIXED
Severity:	normal	CC:	fritzibaby, pajaro, snd.noise
Priority:	NOR	Flags:	fritzibaby: Brainstorm+
Version:	unspecified
Target Milestone:	---
Platform:	Compiled Sources
OS:	Linux
Latest Commit:		Version Fixed In:
Sentry Crash Report:

Description Wegwerf 2016-08-08 16:34:56 UTC

While playing around with the new Transform effect I noticed these two shortcomings:

1. As the angle of rotation is limited to 0...+360° it is only possible to rotate CW. For static compositing this is fine, but when using keyframes it might be necessary to rotate CCW instead. So please add support for rotation from -360°...+360° as, for instance, Affine does.

2. The origin of rotation is the upper left corner. However, I would expect this to be the center of the image, where also the cross marker for moving the frame is located. Please support rotation along the center axis.

Reproducible: Always

Comment 1 Wegwerf 2016-08-09 15:07:45 UTC

3. Can the alpha operation parameter be used at all for a filter/effect?

Comment 2 farid 2017-03-05 14:56:45 UTC

Agree with all suggestions.

Comment 3 alberto 2017-09-12 12:44:08 UTC

Yes, please!

Go to the easy fast fix, moving the origin of the rotation to the center of the image instead of 0,0

This is oneliner fix :)

(Maybe more if you have to migrate old .kdenlive after the change..)

Or the complex one, allow to put set the origin of the rotation

Comment 4 alberto 2017-09-16 23:16:30 UTC

The workaround for this one is to use affine

After trying everything, affine is the only one that keeps everything good about transform (rotation, keyframes, scaling) and its able to rotate using the center of the image

Comment 5 Wegwerf 2017-09-17 18:47:48 UTC

The affine transition is not necessarilya substitute for composite&transform, or the transform effect: affine uses "atop" compositing, which often yields undesired results when working with multiple layers of transparency. Instead, often "over" compositing is desired.

For details on how affine/atop and transform/over differ, please see our toolbox article "compositing with transparency", https://kdenlive.org/project/compositing-with-transparency/.

Comment 6 farid 2021-03-03 16:20:46 UTC

Hello, both CCW rotation and rotate from center options are available since latest release. Closing, but if you encounter any issues don't hesitate to reopen.