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Best method for hair?

Development Discussion Rendering
#1

I’m trying to get reasonable looking hair on a female player model. The hair style is very basic to keep things simple, but it’s still posing problems. I tried using double-sided transparent polys in a layered approach which looked good in blender. Unfortunately, it didn’t work so well in UE4. UE4 doesn’t seem to like double-sided translucent materials.

Is there another way? I thought about poly hair, but I’d like something more sophisticated in appearance. I saw some sample content using hair works which rocked. But it doesn’t look like support was ever officially adopted in UE4.

#2

Currently the only good way is to do it with hair planes + a transparent material -> https://udn.epicgames.com/Three/CreatingHairUsingAlpha.html

#3

I would use alpha tested hair. Simple and works nicely with temporalAA. If you need realistic simulation then you should try Nvidia hairworks or AMD tressFX.

#4

I started to do the hair using alpha masking. But I ran into an issue where the polys were not displaying correctly because the engine was doing odd things with double-sided alphas. There was clipping take place that was making some of the polys come and go seemingly at random.

#5

You need to use alpha testing not alpha blending. If you use transparency with hair you really need per pixel sorting which is extremely expensive to get correct back to front order. But you need set Material blend mode to Masked. https://docs.unrealengine.com/latest/INT/Engine/Rendering/Materials/MaterialProperties/BlendModes/index.html

Then you don’t get any problems with depth order because you always just get single layer of hair and all shading stuff works like normal. Usually alpha tested hair look like a **** but with temporal anti-aliasing it’s actually look pretty good. Then just test which shading mode look best. I would suggest either two sided foliage or any of the subsurface models.

Or if you have performance then just go with Nvidia hairworks and call it a day.