Looking for a brush that simulates the Zebra Super-Marble Gel Pen

[dswolf]

Hello,

I recently got a Wacom tablet and discovered Krita. It is an AWESOME application. I especially love the control of the brushes. However I am one control short.

I am trying to find online or create a brush to simulate the Zebra Super-Marble Gel Pen of the 1990s. I could not find a brush pack with something similar and although I can get close in the brush editor, I can’t quite get the effect I’m looking for.

I need, for every 50 to 100 pixels or so, a new random point selected from a gradient and for that point to continue for the next 50 or 100 pixels. I modified the “d)_Ink-3_Gpen” a few different ways and got close but no cigar:

• Color > Source = Gradient - This part works.
• Color > Mix = Fuzzy Dab. - But this picks a new color on every dab which is much too fast. I need a random generating sensor that is much slower.
• Color > Mix = Fuzzy Dab and General > Brush Tip > Spacing - Can’t get 50px and paints disconnected dots.
• Color > Mix = Distance - Produces strokes that are too repetitive. All strokes start at the beginning of the gradient and follow the same color sequence.
• Color > Mix = Pressure (and other pen sensors) - Requires I pass through the gradient continuously instead of jumping right to the next color.

I am familiar with Python and would be willing to write an extension but I can not find any API exposing the pixel brush engine. It may not exist.

I imagine a software “Sensor” that would pick a random number between 0.0 and 1.0 only every so often and the curve would map to a parameter of the brush (i.e. Color > Mix or General > Size). The “every so often” interval could be number of dabs, distance in pixels, or time in seconds. (Bonus points for also randomizing the interval with something like average and standard deviation).

I am currently using Krita v4.4.3 in Xubuntu 20.04.2.0LTS via flatpak.

Anyway, I would like to know if anyone knows how to get the effect I’m looking for.

Thanks,

-dswolf

[LaTor]

Hi,

I’m not sure if this is what you’re looking for, but @mdfm28 made a brush preset very similar to what you described.

@mdfm28

I made this single brush preset that I use for casual sketching. This supposed to imitate the look and feel of cheap ballpoint pen that I commonly use.

This brush uses multiply blending. Using this brush on a transparent layer may result in a thin white outline. Use in a flat layer or in layer with ‘darken’ blending to remove the outline.

https://drive.google.com/file/d/1T3DWFWn6TCJlc7DjceKKtVqDzvm65YJO/view?usp=sharing
https://drive.google.com/file/d/1T283_nowUHxzrSbtIZ_tLG1XhVYkuQtt/view?usp=sharing

As a tip, you can set the layer blending mode to “Darken” or “Multiply” for the brush preset to create a similar effect to an actual pen drawing on paper.

I hope this helps!

[AhabGreybeard]

Do you have a good close up picture of the stroke made by the Zebra Super-Marble Gel Pen?
That would be useful for anyone who tries to give advice.

Can you upload images of the strokes from the attempts you’ve described above? They would also be useful to see.

[hulmanen]

Some kind of python plugin to change the foreground colour seems like the best bet to do this, maybe creating a palette instead of a gradient and picking colours from that would be simpler in that case?

[dswolf]

Hello All,

Thank you for your replies so far.

@AhabGreybeard ,

Let’s see if Krita-Artists will let me upload this file… Nope, file is too big. Please see it on my dA account:

Zebra Super Marble Demonstration by dswolfstar on DeviantArt

@hulmanen ,

I was so tunnel-visioned in trying to make it work as a brush, I only thought of this after I posted this question. I don’t know how the brush engine will handle the foreground color changing as its working, or even if my script can run while the brush engine is running. But there’s one way to find out. And your right, a palette will be the way to go.

Thanks all,

-dswolf

[dswolf]

@LaTor ,

This is not the effect I am looking for. I’m looking for something that changes color as you write. What I want is demonstrated here:

Zebra Super Marble Demonstration by dswolfstar on DeviantArt

Otherwise, this is and interesting pen in it’s own right and I might download it later anyway for other stuff.

[hulmanen]

Good point about switching colours mid-stroke… most likely not going to go well.

If nothing else works, you could create an animated RGBA brushtip. The downside is, you’d need a separate frame for each distinct shade you need, which might be a lot of frames.

[LaTor]

Hi,

Thank you for including a reference, it made it a lot easier to understand. The closest brush preset that I know that’s similar would be the “moo-office-ballpoint-pretty” from Mojo MOO Draw for Krita – Saeger's Pagination. In the “Mojo Moo Draw” set, there is an additional “Office” Set where the preset is.

I really hope this helps!

[Daishishi]

Hello,

The reference really helped to visualize the effect you want. I made a simple brush mock-up, while I’m not a good brush creator maybe it can help you. If you think it is going in the right direction I’m more than glad to help.

Here the .kpp for this Brush: Zebra Marple Mock-up

[dswolf]

Hello,

Quick update:

I have looked at a couple of proposed brushes. Mojo MOO Draw for Krita moo-office-ballpoint-pretty is interesting but not quite what I want. @Daishishi Zebra Marple Mock-Up is pretty darn close and I may just use that. I like that it picks a different starting color on each new stroke giving each stroke its own flavor. I also like the texture of the stroke. Thank you.

I did explore the possibility of a Python Plugin to no avail. I got a docker with a button and a callback running. The button calls the callback which adjusts the foreground color programmatically when I click it. But I can only seem to hook my callback to my own widgets. I can’t find anywhere else in the program to hook into. And according to this thread from January 2020:

Python Scripting: Hook onto brush event and invoke tool on image possible?

I was thinking about if I could implement a similar behavior to this one as a Krita Python plug-in. However, I couldn’t find a brush stroke event I could connect to and even if I could it seems to me that there is no way to invoke a tool like the color picker at a specific place of the image. What I basically wanted to do is to hook onto the brush stroke event and invoke the color picker just before the stroke is happening to sample the current color at that coordinate, so it will be used …

… there are no on-canvas hooks. So Python Plugin is a dead end.

I may explore the possibility of creating a massive RGBA animated brush or a gradient mapped animated brush. The frames (I agree there will be alot of them, but for a different reason) would animate the transitions and swirls between the colors.

• https://docs.krita.org/en/tutorials/krita-brush-tips/animated_brushes.html
• https://docs.krita.org/en/reference_manual/brushes/brush_settings/brush_tips.html#predefined-brush-tip
• https://docs.krita.org/en/tutorials/krita-brush-tips/gradient_map_brush_tip.html#gradient-brush-tips

(Sorry, I can only post two links at my current level)

It’s late now. I’ll look at it more next weekend. For now, I’m going to use Daishishi’s Zebra Marple Mock-Up.

Thank you all again,

-dswolf

[Daishishi]

Glad you like it. I made a second version a little more tidy up. Now the strokes respect the color you choose, and the variation is predictable and constant. Hopefully is better now.

The way the color gradient work now is: The gradient will go from the chosen color to a color 90° in the color wheel and back (Picture bellow).

With this you can change the distance curve in the Hue parameter to a behaviour more to your liking. You can put negative degrees so the variation goes both way in the color Wheel.

Here the version 2: Zebra Marble Mock-up 2

Cheers

[Hocori_Yuki]

I had that pen!

I can’t make brushes, But Tried those brushes above.

So pretty and fun !!

[dswolf]

Final Update,

I have a new project now so I’m going to put this one on the back burner. @Daishishi 's v2 pen is great step forward. I’ve tweaked is some and plan on tweaking it some more. I’m about 90% happy with what I have so far. Thank you, Daishishi for your help.

I’d also like to thank all of you for your responses.

Cheers,

-dswolf