# Curvature analysis rt shader?

Hi all , is there a real time shader for curvarture analysis ? Basicly mesh analysis that already is there but real time without collapsing the modifier stack.

Thanks in advance

Real time as in game engine? Make a curvature map.

If you mean at render time in a scene, you can use something like this:

can you elaborate on the group node and what it does

a sample file would be nice to work with

thanks
happy bl

the rest of the group is just my way of manipulating the output of that color ramp. Here’s what it looks like on smooth shaded, subsurf Suzanne:

All it does is take the tangent of Geometry tangent and pointiness, and feed it through a 1, 0, 1 color ramp so the edges are white and cavities are black. Relies on mesh density, so it really only works on high face counts. The rest just lets me control the output using math nodes. I use it as a Fac input for mixing.

Not sure what you mean by analysis. I don’t think there is a way to do curvature combs, but here is a quick zebra hack “shader” that allows you to check curvature continuity. The shown is a bevel with 0.9 in profile. It’s basically mapping stripe(s) using reflection coordinates. Either use a image with a stripe (top) or some function creating a stripe (bottom) leaving you whatever controls you desire (power curve is just a sharpness, and the mix let’s me choose between vertical and horizontal stripes).

sirmaxim

interesting way to show it indeed
not certain if you can extract any info from it
but at least you can look at it

would it be possible to upload sample file for this set up

thanks
happy bl

Τhanks all , i think what i want is more complicated than a simple zebra texture. I think i found a solution (in case somebody else wahts it)using a shader i found in blend swap that shows topological lines and mix it with the cavity map. Pointiness works for me cause i have a dense mesh.

Where is that Tangent node from?

it’s a math node set to tangent, but it’s not valid in 2.80+ as the second input socket was removed.

So you can get a similar effect with just a color ramp or map range.

here’s my current experiment trying to get flat to be 0.5:

example result in viewport (cycles only, because pointiness)

Ah ok that explains it. To bad pointiness is only Cycles …

Coming from CAD a good - somewhat usable curvature shader would be fantastic

The 3d print mesh add-on has also a good tool for checking hard edges.

Yeah… I’ve been looking for a solution based solely on normals so it works in both cycles and eevee, however all the solutions for that I’ve found require dFdx(normal) and dFdy(normal) which appears to be impossible in nodes…

Anyway, there’s also an AO node solution that sometimes works for low poly (the cube in the pointiness example has to increase vertex count via insetting all the faces).

so with AO (also only in cycles, sigh):

here is a link to my other post with some of my test results - using mesh add-on or cycles render.

works but not ideal