Review Request 120875: Krita - Fix proposal for brush speed sensor

[Damien de Lemeny]

> On Oct. 28, 2014, 11:24 p.m., Wolthera van Hövell wrote:
> > I tested it and it works well, except the values would need to be 4x more sensitive to work on my wacom graphire 3. Might be different per device.

I tested mapping the physical speed to the sensor value with a log scale and the result feel a lot more natural. It's a subjective scale, differences in high speed are a lot less important than differences in low speed.
I can follow up with a new version of the patch, but that means even more wild guessed constants, that's nowhere near sane programming to my taste :D
There's an implementation of that mapping in libmypaint : https://github.com/mypaint/libmypaint/blob/0a6ad9de9debb9786bcc23cef19446410ac042a5/mypaint-brush.c#L396


- Damien


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On Oct. 28, 2014, 11:10 p.m., Damien de Lemeny wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/120875/
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> 
> (Updated Oct. 28, 2014, 11:10 p.m.)
> 
> 
> Review request for Calligra.
> 
> 
> Repository: calligra
> 
> 
> Description
> -------
> 
> This patch intends to fix the broken speed sensor of the brush tool.
> 
> It's based on a patch I got from Wolthera, which was discarded/unfinished because the output of the sensor remained "blobby".
> 
> I added a smoothing formula to the speed output :
> 
> output_speed = current_speed * 0.1 + last_speed * 0.9
> 
> 
> The used numeric values are either eyeballed or wild guessed from usage. There's certainly room for improvements on this patch.
> 
> 
> Diffs
> -----
> 
>   krita/image/brushengine/kis_paint_information.cc 264ad43 
>   krita/image/kis_distance_information.h 70fa25e 
>   krita/image/kis_distance_information.cpp 1c1c847 
>   krita/plugins/paintops/libpaintop/sensors/kis_dynamic_sensors.cc 6b10e2b 
> 
> Diff: https://git.reviewboard.kde.org/r/120875/diff/
> 
> 
> Testing
> -------
> 
> I tested the ux of a speed bound preset before and after the patch and compared to the behaviour of a similar test brush in Mypaint.
> Results are noticeable improvements when painting strokes at different speeds with the fix.
> 
> It's also been tested by Wolthera
> 
> 
> Thanks,
> 
> Damien de Lemeny
> 
>

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