curvature shader

[aphexx]

hi, i wonder if there will ever be a geometry based shader that is oriented on covexity of the geometry.
you might want to say, that you can use a dirt shader to render the concavitys/AO of a mesh and invert it in an outputmap, but for small and detailed effects on corners of meshes, this is not enough. and what if there are no concavitys that can produce AO?

my idea is, to simulate dirt or rust effects like these on the corners, without using vertex colors or UV and Textures:


to have such a shader in vray would be killer...also it would be a world premiere i think?

[dlparisi]

Should be pretty easy to do with the vraydirt shader and a noise map in the radius slot.

[joconnell]

There's also a map called tension written by grant adam at rpmanager.com that does this. Great for things like whitecaps on waves and so on.

[raymarcher]

http://www.neilblevins.com/cg_educat...x_map_wear.htm

or this way

[duke2]

As Neil points out, it's geometry based so it certainly has it's limitations. I think what the original poster is after is something like this:

http://www.finalrender.com/products/...PID=45&FID=587

If those silly people made those shaders work with MR and VRay, they'd sell a whole lot more!

[raymarcher]

I wouldn't mind paying for vray 2.0 if such shaders as curvature, layered shaders (mix8layer/frlayerdshader), fast occlusion, etc weere included.

[Da_elf]

even if they are not im sure its going to be way cool

[duke2]

I hope Vlado doesn't kill me for this, but it's probably worth telling you guys that VRay 2.0 will, in fact, make you coffee.

[aphexx]

Should be pretty easy to do with the vraydirt shader and a noise map in the radius slot.

really? i will give it a try, but i doubt one can achieve those corners on any covexity of a mesh.
did you ever used the map for this effect?

There's also a map called tension written by grant adam at rpmanager.com that does this. Great for things like whitecaps on waves and so on.

thanks for the tip,but i know this modifier.
its no map, but a modifier. and it needs a reference pose and it uses vertex color so its not what i search for.

http://www.neilblevins.com/cg_educat...x_map_wear.htm
or this way

yes i know this and i use this. but it is vertex color based.
see this link for a piece where i use it.

As Neil points out, it's geometry based so it certainly has it's limitations. I think what the original poster is after is something like this:
http://www.finalrender.com/products/...PID=45&FID=587
If those silly people made those shaders work with MR and VRay, they'd sell a whole lot more!

indeed, this is what the original poster is after
i wanted to post this link in the initial post, but i feared that then many people would suggest a vraydirtmap to achieve the effect, due to not really understanding what i meant.

I hope Vlado doesn't kill me for this, but it's probably worth telling you guys that VRay 2.0 will, in fact, make you coffee.

i'm totally speechless

[MasterBercon]

Curvature shader wouldn't probably return anything for a box. The surface doesn't have any curvature, its just 6 independet planes (unless smoothed). If it would be chamfered box it would be a different case. At least thats what I think.

If somebody has some clever idea of how to compute surface curvature I could try implementing it.

[raymarcher]

Yeah, you can always count on MasterBercon, autodesk should pay you big bucks to implement your shaders into max, or chaosgroup should buy and perfect them as an asset for vray.

Another solution, perhaps a distorted vray edge shader as mask in a mix?

[MasterBercon]

Distorting vray edge texture would be preeetty hard thing to do because of how the distance to the nearest edge is computed. And if you thrown in something like displacement you can forget it. I think I saw curvature shader for mental ray but I'm not sure if its source codes were available or if it was just a blackbox like fR's shader.

[instinct]

This one has sources available so it might be worth a look. Havent checked myself tho.

http://www.tomcowland.com/mentalray/...ure/index.html

Regards,
Thorsten

[aphexx]

This one has sources available so it might be worth a look. Havent checked myself tho.
http://www.tomcowland.com/mentalray/...ure/index.html
Regards,
Thorsten

yes it is a mental ray shader from tom cowland.
you can get it into max, when placing the dll from folder "lib (win)" here:
...\Autodesk\3ds Max 2009\mentalray\shaders_autoload\shaders

and the .mi file from folder "include" here:
...\Autodesk\3ds Max 2009\mentalray\shaders_autoload\include

but i never got it working properly..nor understood it...

[aphexx]

@masterbercon: thank you for your help.
i'm no programmer, so i got no real clue on what to do...
isnt it like angle select in 3dsmax? so that can find out angles between the triangles?

we want to create a map that renders black and white masks just like any noise map but that is based on the angles that are defined by the triangles.
so that we can place this map i.e. in the mix amount slot of a mix map.

we want to find out angles between 90° and 180° at shading time.
and we want all noise/output controls in there, that are also in the other procedural maps.
also we want the ability to put nested maps in the color slots, so that the map can also function as a standart color shader that creates i.e. cascading effects like undercoatpaint under an intact paint and at the bottom comes the rust.
like here


and that all without vertex color or other workarounds.
fully automated.

so perhaps the face normals of a mesh have to be sampled for each shading point by a given radius, so that we get some kind of topology map?