How to do anisotropic hair mesh with flow map?

joeyq

There is no documentation or tutorial on the internet of how to do anisotropic hair in Godot. How the flow maps should look like, tips or tricks, nothing. In the official documentation (https://docs.godotengine.org/en/3.0/tutorials/3d/spatial_material.html) there is a screenshot and short description, but no sample project.

If anyone has a sample project or detailed instructions with pictures would be appreciated. Thanks in advance

Megalomaniak

godot demo projects repo should include a material tester project that should have some materials in there, looks like the aluminium material has a flow map and might be a brushed aluminium which would involve anisotropic specular, but it's been a while since i last looked at the demos so you'd have to confirm yourself: https://github.com/godotengine/godot-demo-projects

joeyq

Unfortunately unhelpful demo, the flow map isn't even used in the project.

cybereality

You might be able to find the common format in other engines and see if it works in Godot.

Megalomaniak

OK, but I did see a aluminium flowmap included in the project file structure. What happens if drag and drop it over that [empty] field?

Calinou

I believe the flowmap texture is expected to only contain red, green and alpha channels – the flowmap's blue channel is ignored. The red channel represents X distortion while the green channel represents Y distortion of the specular reflection. A value of 128 on either channel represents no distortion. A value of 0 represents maximum negative distortion, while a value of 255 represents maximum positive distortion. The alpha channel is optionally used to scale anisotropy intensity in specific parts of the texture (fully opaque = full effect, fully transparent = none).

That's what the shader code tells me at least.

Edit: I opened a pull request to document this :)

Megalomaniak

That's how most derivative maps(dfdx/dfdy) work, flow maps are just a derivative of the concept(no pun intended) far as I can tell.