Special Shift brush question

[kelanhordos]

I have a question regarding how this Special > Shift brush functions. One very confusing thing for me when I started trying to replicate blending brushes in other programs was trying to use the first built in custom brush under the smudge & spread "Drop" brush. It has a nice paint pushing quality, but it wouldn't behave as I expected it to on both sides of an image(demonstrated below). After recently revisiting trying to make some blending brushes, and figure out exactly how the SHIFT parameter functions I have narrowed down the issue, but am still at a loss so am wondering if anyone here could explain. The closest I could find of previous discussion on the forum is this on from 2019, but I couldn't find more: https://forum.tvpaint.com/viewtopic.php ... sh#p116623

The video below demonstrates me using the default Special Shift brush with a bit of size and power increased. Shift behaves normally as you would expect, pushing and pulling paint in the direction of your brush stroke, until you get to both Aspect and Angle being set to random at the same time(which is part of what the "Drop" blending brush has for settings). When these are both set to random, going from right to left behaves as you would expect, but going from left to right cause the shift to occur backwards seemingly, in that it moves the pixels to the left. My expectation would be that it would continue to go in the direction of your strokes so you could paint similarly on both sides of something but maybe I am missing something? These two settings being random(along with size) adds a nice jitter/scatter to the brush that I haven't figured out how to mimic otherwise, and I just want to double check if this is intended behaviour or not.

https://www.youtube.com/watch?v=pV2OUolBlWw

[Peter Wassink]

The brush engine is at least 20 years old, i hope that whatever was intended is still available in some archive... but i am not sure.
By the way... I love how deep you dive in what is possible with tvpaint, and lets hope we will seem some new brush engine improvements soon.