Add pixels0rt filter

[namikiri]

Pixel sorting, now for all open and awesome video editors!

This filter implements 4-directional pixel sorting based on threshold with direct and reversed sorting order and transparency threshold for using it in masks.

Thresholds are keyframe-friendly and accept values from 0 to 1.

The result looks like this:

Additionally, this commit adds CMakeCache.txt into .gitignore. I couldn't remove it from the commits so please let me know how to fix that if it's a problem.

Any comments on the code are appreciated.

[namikiri]

Optional but might be useful: QML files for Shotcut which I was using during the effect development:
https://gist.github.com/namikiri/84b092891c2717ca70402054968c3b15

They can be made a bit incorrectly as I'm new to QML and just took another effects as examples.

[shadowfax65]

@namikiri: What are the values for the different directions? From the QML file I thought 0 (top to bottom), 1 (bottom to top), 2 (left to right), 3 (right to left), but the value range is limited from 0 to 1. The .c file also suggests 0/1/2/3 but when I try this in Kdenlive only 0 (top to bottom) works.

I can get it to work with 0, 0.25, 0.5, and 0.75 ;-)

[namikiri]

@shadowfax65

I can get it to work with 0, 0.25, 0.5, and 0.75 ;-)

You have guessed it right! As Frei0r parameter types are BOOL, STRING, COLOR and DOUBLE, I chose the most suitable variant to pass the direction into the filter by dividing the range 0..1 into 4 subranges.

[luzpaz]

Thanks for working on this. Looking forward to this getting merged.

[shadowfax65]

Thanks for working on this. Looking forward to this getting merged.

Any idea when this will happen, @jaromil?