Hard edge on low poly hair?

Aneroit · Oct 2017

Hello everyone!

I'll cut straight to the point! I'm having a problem with my low poly hair: basicly I'm seeing hard edges on my hair. It's driving me nuts! I was trying to rotate planes so they could cover each other but it does not seem to work. Densening planes, kinda helped by hiding some portions of it (I think so any way

), but it's still not enough.

Do you have any suggestions?

Thanks in advance, and have a good one!

Image: https://us.v-cdn.net/5021068/uploads/editor/wl/z8fwl996tznm.jpg

Image: https://us.v-cdn.net/5021068/uploads/editor/o4/hpp7z08rsi94.jpg

poopipe · Oct 2017

See what it's like without the textures on. I suspect it's an alpha artefact

Butthair · Oct 2017

What software are you using and do you plan on taking this into game engine? if so check it there to see if it's a software problem or graphics card.

Game engines sort transparency better than 3d softwares, so sorting is usually an issue that can't be avoided.

Sort order is determined by newest vs oldest vertex created.

Aside from sorting, I think the shading/rendering of the hair could also be an issue because of vertex normals. If they are all aligned in world z, they might reduce the dark pockets. This is usually done for foliage so they shade to the world vs self shade.

Obscura · Oct 2017

You can try adjusting the vertex normals. I don't know how much common is this nowadays, but in the past they used to project the normals of a sphere to the hair planes, because of similar reasons.

radiancef0rge · Oct 2017

Obscura said:

You can try adjusting the vertex normals. I don't know how much common is this nowadays, but in the past they used to project the normals of a sphere to the hair planes, because of similar reasons.

yeah i think thats pretty common practise. we wrap different clumps of hair in spheres like ponytails for example get their own spherical vert normals

thomasp · Oct 2017

you seem to be looking right down the flat tops of your hair strips. additionally it appears you're running unreal and probably the builtin hair shader which has a way of highlighting planes. if that sounds about right then not much you can do apart from reshaping the strips, making them messier and angling some of them them a bit more perpendicular to the camera.

do you really need that curvature from root to tip in the hair strips everywhere in the top section? might be worth a try to create the top with a solid underlayer that provides the volume and dress it up with a layer of fairly flat floating planes to minimize the issue. then you will have less of an issue with the viewing angles and more polygons to spend to mask the gaps between the strips.
the sides and rest of hair can then be done the standard way.

Aneroit · Oct 2017

poopipe said:

See what it's like without the textures on. I suspect it's an alpha artefact

It's solid grey color. I'll post image later on.

Well yes, I did transfered vertex normals from sphere. And yes, I'm going to use this hair in game... For presentation purposes.

thomasp - you are completely right! I'm using UE4 with their shader, and I made these screenshots looking right down the flat tops.

[...] might be worth a try to create the top with a solid underlayer that provides the volume and dress it up with a layer of fairly flat floating planes to minimize the issue. then you will have less of an issue with the viewing angles and more polygons to spend to mask the gaps between the strips.[...]

I'm not sure if I understand you: do you suggest to just paint solid white on the bottom of hair strips... or make hair cap with some solid color?

Butthair said:

[...]Aside from sorting, I think the shading/rendering of the hair could also be an issue because of vertex normals. If they are all aligned in world z, they might reduce the dark pockets. This is usually done for foliage so they shade to the world vs self shade.

But what's the point of aligning them if I transferred them from a sphere? The problem is, transferring vertex normals does not solve the dark pockets problem.

thomasp · Oct 2017

hey what i mean is due to the curvature of the strips you'll always be able to see 'into' the hair volume right down those planes when you view the head from the front. you need to angle the poly strips differently and/or add a lot more of them to blend over those gaps. easiest would be to make a solid underlayer to create volume and place overlapping little planes on top for the strand detail.

Hard edge on low poly hair?

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