Hello,

I figured this was the best place to ask some help on recreating a brush.
I am an artist who used SAI for a long time and I grew very fond of some of it's default brushes. there are 2 in particular that, despite my efforts, I couldn't recreate accurately (or even inaccurately) in Krita, and I'm starting to think it is not possible to do it. that's where I need some help I doubt it's impossible to recreate these tools as they seem pretty basic.

The first tool is the marker tool. I have made a picture to show how it works on SAI, and how the closest brush I could find looks on Krita works in comparison (the basic_tip_default) , please look below.


I tried to do the same gesture as accurately as I could in SAI and Krita, and ended up with 2 wildly different results. the marker has, as my friend described, some kind of persistance and dillution, and acts like wet paint, unlike the Krita tool. If I lift the pencil and put it back on the tablet to continue the line, you'll have a hard time seeing where I did it on SAI, but on Krita, it's very obvious. or look at every place where the lines cross, on Krita the lines "stack" and end up looking much darker.
I have toyed with options everywhere in Krita and couldn't find one that reproduces the SAI tool's effect. Is it possible to do it?



The second tool is the blur tool on SAI. it's a brush which, obviously, blurs.
I could kinda reproduce that tool (I tool the FX_blur_light tool, and just toyed with the values), but the two big problems is that it has a significant performance hit (like, the brush lags a lot, especially when compared to the absolutely instant blur brush on SAI). Is there a better way to blur through a brush? lastly, the big problem with my solution is that this brush doesn't support pressure at all. I can't make it apply a stronger blur if I press harder, or the opposite. Can it be done?


Thanks in advance for the help.

That's because Sai's marker actually uses subtle color smudging.

I have a brush bundle here, check out the 'paint_dull_radius' for my best attempt at something similar.

oh cool! thanks TheraHedwig!

I have given them a try, they emulate the feel of the marker tool pretty well but they aren't perfect (and I dare guess, that's because they're "color smudge" brushes and not just "pixel" brushes. of course I don't know for sure!).
for example you can't go from light grey to pure black in one motion, you have to keep coloring the same area for it to become fully saturated, and it looks jittery if you try to draw an almost horizontal/vertical line (especially easy to see if you reduce the size of the brush to <7 px). so because of those, these brushes are very good but not perfect.
I'm kinda bummed, I guess there is no way to reproduce that tool easily!

What about the blur tool? am I doing it right or is there a better (and more instant) way? I'm basically using a filter brush, but it doesn't seem to register pressure (so it applies 100% of the filter whether my pen crushes my tablet or I lightly touch it).

In the case of filter brushes, what can be done is changing the spacing or the strength of the filter. They should be much faster in the 3.0 release though. You might also want to check the light-blue brushes in that pack. Strength can be done with opacity, if I recall correctly.

The thing with colorsmudge is that it doesn't have subpixel precision, because otherwise you get artefacts. It's something that is on the todo. Edit: I just made an experimental commit involving fixing this. Let's hope it's accepted (probably will)

BTW, considering you're such a SAI user, could you maybe explain what people mean with 'Sai just has better color blending', we can't seem to get people to give actual comparisons between Krita and Sai blending, meaning we can't improve our blending method... :/

Based on some quick tests I did, SAI seems to replace the RGB values on the current layer with the selected color, compares the alpha value on the layer with the alpha value from the marker, then uses the alpha from the layer if it was higher. (I had blending disabled during this, so I was only looking at how it deals with the opacity of multiple strokes.)

I don't see anything that does the same in Krita, but if you use the "Alpha Darken" brush blending mode, you'll get something that ends up working a little more like the marker in SAI, as long as you're only using one color. However, at this time, alpha darken doesn't seem to work when using a brush that changes opacity based on pen pressure, rendering it a bit useless (I've filed a bug report for this).

TheraHedwig wrote:BTW, considering you're such a SAI user, could you maybe explain what people mean with 'Sai just has better color blending', we can't seem to get people to give actual comparisons between Krita and Sai blending, meaning we can't improve our blending method... :/

I have been using Krita for about half a year (since 2.9 came out!) so my memories aren't completely fresh about how SAI works. all I can say is that it feels more smooth/smudgy. but I asked a friend of mine who still uses SAI what he thinks of it, and I agree with what he said, so I think it might be of use to you as you are a dev!

sai has three blending options : dilution, blending, persistence. now persistence is like smudge but what it does is it sort of, as you put the brush down it picks up the colour youre painting over, and applies some of that colour to your brush. so it gives the illusion of "smudging", ie, the colour underneath 'persists'.

Basically, it's what the marker does. if the color you're trying to use is lighter than the color that's already on canvas, then it is not added (and stacked and ends up looking darker). that's how I'd describe it at least, and most tools work this way except for the airbrush tool. I hope this can be of use. I notice that's how brushes work as well on Krita when you enable pressure opacity (until you lift the pen off the tablet, then the colors will stack and get darker).

Why don't you try to use SAI and see for yourself? I think trying it first hand would be better than a million explanations and descriptions! (although, I guess you have tried SAI before, since your brush feel very close to the marker tool).

Well, the thing is, I am on Linux. And I did use Sai a long while ago, but it's been a while, and it's very tricky to get working on Linux, hence why I would like to see image-examples...

it looks like you want Painting Mode: Wash behavior but with all strokes and not only with the active stroke.

TheraHedwig wrote:Well, the thing is, I am on Linux. And I did use Sai a long while ago, but it's been a while, and it's very tricky to get working on Linux, hence why I would like to see image-examples...

Here's an example of stacking strokes of varying opacity.

TheraHedwig wrote:Well, the thing is, I am on Linux. And I did use Sai a long while ago, but it's been a while, and it's very tricky to get working on Linux, hence why I would like to see image-examples...

oh don't tell me about it. I gave up running it through wine/playonlinux and I run it through a virtual machine now (fiddling with virtualbox a little allows you to use your tablet through it), maybe you could try to look into that?
But if you for some reason you can't I'd be glad to supply pictures of SAI examples, although I think nicholasl does a much better job than me, because unlike me it seems he can explain/describe things in a technical way

Hm... I recalled a patch from a while back that never got in because of lack of manpower, but it was supossed to do the same thing: viewtopic.php?f=156&t=119773

I have messaged the author, let's hope he gets back to us

tresmon, even if you can't explain technically, just examples of pure colours like red+blue or red+green is really helpful
Here's an example of what I am able to diagnose from the result you get when mixing red and green. Someone suggested that Sai might be mixing linearly(resulting in the first mixture with the quite bright yellow) but I am doubting that.

SAI's own tools act different from each others, too. the marker tool has bleeding and persistence, while the pencil brush does not. The pencil brush acts pretty much like Krita's brushes in term of how colors mix.

here's some strokes done with the marker tool. I have tired all kind of values for the sliders (persistence and bleeding), I hope it can be of use.
http://postimg.org/image/ua34tfbpj/

again, it's just a few strokes with different options, but it shows only so little (and coupled with my lack of knowledge of what does what exactly and the fact English is not my main language thus limiting my understanding), it's hard to really get a firm idea of how colors would mix. For example, sometimes, the marker tool could even act like a color smudger (not pictured), it just depends on how much you press on the stylus).
so I'd like to mention again that trying the brushes first hand directly on SAI would provide a lot more information than this

tresmon wrote:so I'd like to mention again that trying the brushes first hand directly on SAI would provide a lot more information than this

Nope, sadly enough this actually helps a lot

We have a brush here which is able to choose to smudge the alpha(transparency) and the colour seperately.

No bleeding = no color smudge.
Full bleeding = colors mixing.
No persistence = alpha smudge.
Full persistence = alpha is fully maintained and only painted if the smudge alpha is 0...

So this would be a separate option from Dulling and Smearing in the color smudge brush. It's not really easy to implement, because there still seems to be a blending mode involved somehow. The bleeding part is easy, but it'll take some time to exactly describe how the persistence slider should exactly be interpreted in code.