I'd like to know how to do stylized shading.

I came across this article (PDF format):

http://home.postech.ac.kr/~sionson/cs499/r...20Animation.pdf

(I found the paper on this page:

http://www.cs.berkeley.edu/~eden/npr/meeting/index.html

which has various interesting toon-related ideas. Here is also a link to the abstract/summary )


Anyway, I'd like to know if this can somehow be done with Hash AM as is, perhaps even through a post-processing effect, or else if someone might consider even creating a custom shader plugin for it. They seem to explain the math involved for that purpose. (Do either Andy Whittock or Marcel Bricman still do plug-ins? Perhaps they might see this as an interesting or worthwhile project.)

I'd wonder if this approach could even be used on shadows and depth-shading to slightly distort them, to make toon-rendering look a little less rotoscoped, as it sometimes tends to do.

The thing is that at least shadows are renderable separately, so at least that might help in post-processing them. But specular highlights aren't renderable separately, so I'm assuming it might require a custom-made plugin to do this vector-field modification/stylization of highlights.

Stylized highlights seem like a cool way to make an object look more authentically like toon/anime instead of like a rotoscope of a 3D object. Particularly if you were rendering a mech, car, motorcycle, etc with metallic surface, your stylized highlights would make it look cooler, imho. Or even just glass window panes, windshields -- or what about the highlights specific to anime eyes?

Can anyone comment on the feasibility of what I'm talking about?

Specular Intensity-type decals work pretty darn well, look at

http://demented3d.com/3d/nancy.jpg

The squiggly highlights in the hair are created with a decal set to Specular Intensity.

When a light passes over it the highlights light up. They fade away as it passes.

Dont forget you dont have to use 1 model to complete all your shots, if you need special highlights for that *killer shot* .. duplicate your model and texture it to match what you need, then render.

Oh, and dont forget the hash toon-shader itself! Look at the Nancy picture again, the black "ink highlight" across her suit was done entirely using the toon-shaders gradient system. Similarly used on the gun.

So with decals and the shader you can pretty easily duplicate most of the effects in that pdf. Without the brain-numbing math, heh.

Hmm, well just to understand, how would I do something like a windshield? What kind of map would be appropriate? It's one thing to have a decal specularity-map to achieve a particular shape of highlight in a still shot, but under animation I'd worry that it will be fixed on the object in a way that would not animate properly.

The ink effect you showed looks cool though. Sorry, I didn't notice it before (thought it was a stripe).
That looks more like something that might animate better. Perhaps using a white ink effect, it could be made to look like a stylized specular highlight.

One idea I've had -- but which I haven't been able to try out yet -- is to apply a normal map on the surface that looks like a wave pattern. This should allow you create specular highlights that don't necessarily match the contour of the surface. It may also be possible to manipulate the specularity of an object by adding a specular-only light with a light list that affects only that object, and constraining the light to the object so that it moves independently of the main light source.

Aha, now this is what immediately came to my mind, when I was considering the problem. Because a normal map is a surface-projected vector field anyway.

Now if I go with that, I was wondering about what the normal map image has to look like, in order to produce a particular desired look.

I was also wondering if anyone has actually done anything like this for toon purposes before.

To me, stylized highlights are critical to achieving an authentic toon look.

Like I said, too bad there's no way to automate this process through a stylized shader plugin.

I remember once seeing Yves do a beautiful rendering of toon waves on a shoreline, and thought perhaps he might have some insight on this as well.