Rune Skovbo JohansenOct 16

I had an impulse to see if I could make a basic hair shader that doesn't require any specially made meshes or textures.

The shapes below are just standard Unity spheres and capsules and only a simple normal map is used; no other textures. Left is Unity's Standard shader; right is the same, but with brute force anisotropic shading, running the BRDF function up to 50 times and taking a weighted average.

Of course, non-brute force approaches are possible too, but way harder to make look good.

Show threadRune Skovbo JohansenOct 16
Ok, I think this hair shader experiment is done for now.
Show threadRune Skovbo JohansenOct 16

My partner saw the previous video and commented it looked like hair dye commercials. I had her help me tweak the parameters to look more natural. Increased normal map strength and slightly decreased smoothness did the trick. Parameters I did nothing to implement; they come from Unity's shading model.

I'm also messing with the parameters a bit in this video.

Show threadRune Skovbo JohansenOct 16
I found some characters on the Asset Store and tried changing the hair material to use my shader. Luckily they all already had hair aligned vertically in the UV map, although not 100% for wavy/curly hair, which compromises my shader slightly.
(This asset: https://assetstore.unity.com/packages/3d/characters/humanoids/humans/npc-casual-set-00-326131)
Show threadtoerror
@runevision Looks better, but it does lose some of the depth on more textured hair; Maybe just incorporating some lighting from the original normals would restore some of that lower frequency detail? ( or possibly just the shadows )
Oct 16 at 10:27pmWeb
Show threadRune Skovbo JohansenOct 17
@toerror Ah, well I intentionally turned the normal strength down since I thought that looked more natural. My interpretation is that the original materials used exaggerated normals to compensate for lack of anisotropic lighting, since very strong directional normals can produce a crude version of it.
Show threadtoerrorOct 17
@runevision Hmm.. I'm really imagining a half lambert term pushed through AO, but maybe it would make it start looking like plastic again..