[SD] any procedural paint stroke example?

bitinn

Hi,

I am wondering if anyone have seen some examples of substance material where they apply brush stamp based on an input map. Say a height map or something like that.

My problem is I want to apply the brush stamp repeatedly like an actual human painter but SD isn't designed to do that: node like Tile Sampler apply input at a certain interval (or some randomized interval), but that's not how a painter would work, especially when overlaying strokes with low alpha value to create interesting color variations.

User contributed node like https://share.allegorithmic.com/libraries/2817 isn't what I am looking for neither: I don't want to distort existing color input, I want to procedurally generate them.

Any suggestion?

poopipe

You can probably get a long way towards what you want using a tile sampler with vector maps for offset /orientation etc.

bitinn

poopipe said:

You can probably get a long way towards what you want using a tile sampler with vector maps for offset /orientation etc.

honestly, I used them before but if you take a look at the google image search result from "tile sampler + vector map", I don't think they are sufficient.

The best result by far is Matthias's work: https://www.artstation.com/artwork/4nKDn

But it's still too easy to see the procedural stamping nature of it (compare to an actual handpainted object.)

There are tons of stylized substance material on artstation of course, but the ones I look closely suggests none of them are created in the same process a handpainting texture author would use (basically the brush stroke feel were added at the end intentionally to give the "handpainted" feel, not the actual effect of procedural painting)

poopipe

I know what you mean.  

You face a problem with this sort of thing because you cant analyze a whole image at once in an fx map you can only take point samples) and therefore cannot  make an algorithm that works out how to paint it. 

Experiment with the tile sampler and vector map and try to articulate what it's not doing right.  We might be able to suggest fixes

bitinn

poopipe said:

I know what you mean.  

You face a problem with this sort of thing because you cant analyze a whole image at once in an fx map you can only take point samples) and therefore cannot  make an algorithm that works out how to paint it. 

Experiment with the tile sampler and vector map and try to articulate what it's not doing right.  We might be able to suggest fixes

You are correct.

But let me explain my problem:

- My current approach is to create procedural material that take baked maps like uv/world normal/position/occlusion, because I don't believe I can produce the paint result without knowing some mesh info (that's the information a handpainting texture artist would have.)

- I am thinking along the same line of my last year's experiment: https://polycount.com/discussion/comment/2580980/#Comment_2580980

- My issue with trying to find artstation reference is that they are 99% purely procedural and doesn't rely on mesh info (aka they tessellate geometry using height map).

- While they are awesome, in actual games we usually couldn't use tessellation due to performance budget constraint, and this is the case for my current project.

- Now look at the process of handpainting a rock, and compare it to the best stylized rock material I could find, you can see why it is so hard for procedural material to capture the handpainting feel. (see below)

So my questions are simply:

- Besides mentioned approaches, are there any other starting point to lying down brush stroke procedurally in SD?

- Have you seen anyone that does it creatively in SD?

- Or should I not try to solve it entirely with SD, but fallback to painting additional details with SP or PS?

I am not trying to be lazy and make others finish my job, just wondering if there are prior-art.

Clark Coots

If you want it to feel like there's an under painting and overlapping strokes that build up, could you just use a Tile Sampler to splatter a paint stroke shape. Either blend Max or Add/Sub, then gradient map it to add color. Do that for your larger shapes and with your smaller shapes to hopefully simulate a large stroke to small stroke then feel blend them on top of each other. You may experiment with Tile Sampler Color with alpha too, so simulate opacity in a brush stroke.

In your 2D reference above those noise patterns should be easy to do in SD if you're just looking for general painty splotches on a model.

poopipe

^^exactly 

The hard part is working out which direction you want the strokes to face in. 

What you want if you're interested in specifying stroke direction is a direction map (not the same as a flow map) and unfortunately there's no way to paint one of those in any comercially available software I've come across. 

However, if you don't need to paint in swirls etc and simply want strokes to follow the shape of the asset you can create a map with direction information from various baked maps and feed it to some tile samplers. 


if you want something that looks like the lower example - that's basically just curvature 

Steppenwolf

bitinn said:

The best result by far is Matthias's work: https://www.artstation.com/artwork/4nKDn

But it's still too easy to see the procedural stamping nature of it (compare to an actual handpainted object.)

Make sure to read my accompanying blog post to the oil painting frame. I'm not much experienced with hand painted styles but my technique there can probably be pushed a lot further to avoid procedural look. Maybe don't shy away from importing some bitmaps of paint stroke shapes for a more believable hand painted look. Not everything needs to be 100% procedural.