Help creating pencil brush

[hulmanen]

I’m trying to create a brush that emulates drawing with pencil on paper. Specifically, I’m looking to create a brush that has a strong texture to it, but when pressed very hard, especially with the tip of the pencil, negates the texture and just produces a solid color. Like how a pencil, when pressed to paper, will collapse the texture of rough paper enough to produce a smooth line.

Here’s what I have, on the left, and what I want to get, on the right.

I was thinking if I could just control the contribution of the texture pattern with e.g. pressure, that should do it. I can’t find any way to get the texture contribution to go to 0, though. I would do this with masked brush instead, but unfortunately if I select a large texture for the masked brush, it strays outside the bounds of the brush tip and affects areas already drawn on.

Does anyone have any ideas?

[AhabGreybeard]

This is a total hack, the texture is wrong, and I don’t really understand most of the things I did but it seems to getting there:

Here is the .kpp file:
Hacked-Pencil.kpp

The key point is that the Masked Brush Brush Tip is set to Colour Dodge blending mode. (Please don’t ask me why that works.)
I had to bring the pressure controlled main Opacity down to a low level at the high pressure end to get an even distribution of ‘filling’ effect along the line.

You may want to experiment with it to see if you can make it better.

[Lynx3d]

Patterns, especially in Subtract Alpha mode, are really quite tricky to adjust, unfortunately.
You basically have to play with contrast and brightness of the pattern until you’re satisfied, and to make matters worse, every pattern has somewhat different brightness distribution that needs to be tweaked again.
Especially the extremes in the pattern are hard to deal with, and the cutoff modes don’t really help either, a clamp mode would be nice to get rid of some persistent holes.

I’ve spent plenty of time on tweaking pattern parameters already, and yet it never feels perfect

Maybe I can come up with an idea for a more intuitive pattern blending algorithm.

[tiar]

There is one pretty interesting feature request here: 375155 – Add option to texture each dab instead of stroke . I believe that Masked Brush with Height blending mode, whatever that mode is, could help too, but for that, we need to figure out what the formula for the Height blending mode is…

[hulmanen]

Texturing each dab might work. I’m not quite sure if it would solve the case I’m looking for. The biggest issue I have is that the pattern strength doesn’t do what I think it should - it multiplies the whole stamp, not just the pattern being applied.

[hulmanen]

You’ve hit on something there, although I don’t understand what the masked brush does here, exactly. The problem for me is that once I add size controls to the equation, masked brush starts breaking. See video here:

2021 03 10 20 29 32

Notice how the stroke keeps darkening. This is because the masked brush is not restricted to the current stamp but is applied to the whole stroke, I think.

Also at the end, I switch to white to erase and something really breaks.

[tiar]

Nice artifacts at the end… (must be some nasty bug :/)

Size of the masked brush is not restricted to the size of the brush tip, so it’s best to kind of link them together - which isn’t really convenient on the current brush editor…

[hulmanen]

Well, I seem to have created a whole slew of threads around what ends up being the same issue. Sorry!

I’ll keep my brush testing here. On that note, I do think I got somewhere - this is all with one brush, no size adjustments etc. between strokes.:

@Deevad mentioned using the masked brush to just darken out the high-pressure end of the brush. I tried that, but then I was left with the problem that the only compositing options for the texture pattern are multiply and subtract. None of those produce the hard look I want, since they will output a lot of graytones.

That, and @tiar mentioning that the size settings of the brush and masked brush should be the same got me thinking and after a lot of experimentation I arrived at:

• base brush with a stamp I made, with size linked to tilt elevation.

• Texture pattern for the base texture. I used Subtract alpha.

• Pattern strength mapped to pressure and to tilt elevation. The latter is set up so that as the pen reaches the most upright angle, the pattern strength is boosted to max so that the pattern has the least effect possible. (It still kind of gets me that higher strength is less pattern effect here)

• For masked brush:

• I created a heavily textured version of the brush stamp I used in brush tip settings. This is to ensure the masked brush occupies the same footprint as the main brush does. The brush tip is animated, too, so that at higher pressure it is more of a solid color and at lighter pressure a very heavily textured thing. (Or the other way around? It’s kind of hard to figure out how the animated brush works, so I created two versions with opposite layer orders…)

• Inversely mapped Flow to pressure, and adjusted the overall strength to 64% or so.

The texture is maybe a bit extra rough now, the pressure response is very finicky as is the tilt response, and the stamp shows through a bit too much for now, but this is as close as I’ve gotten so far. I can’t get 100% coverage at full pressure still as I have to use the masked brush to get the hard texture I want. It seems we can get one or the other, I prefer this option. I’ll post a preset if you folks want, but I think I need to work on usability still.