Fastest shader for trees

Unity Engine
1

Hi, from these 4, which is the fastest shader for trees? (for mobile game)

a) Nature / Tree Soft Occlusion Leaves
b) Transparent / Vertex Lit
c) Transparent / Cutout / Soft Edge Unlit
d) Transparent / Cutout / Diffuse
e) Transparent / Cutout / Vertex Lit

Thanks…

Edit: Also found this → Unlit / Transparent Cutout. This may be also fast, isn’t it?

2

Unlit cutout will be the fastest, but comes with the obvious drawback of having no lighting, so if this doesn’t look out of place in your scene, go with that. E would be the fastest out of the versions with lighting though.

Vertex lit always tends to be the fastest lighting calculation, and cutout transparencies are faster than alpha transparencies because they just clip anything below the threshold rather than doing complex alpha rendering.

3

Not necessarily; on quite a lot of mobile devices, cutout (alpha test) is actually substantially slower than alpha blending due to the way their GPUs work.

So Transparent/Vertex Lit might be the fastest… but it’s still a surface shader. You might want to pick one of the mobile shaders that comes with Unity instead - they’ll have a bit less overhead.

The downsides to using an alpha blend shader rather than an alpha test shader are the alpha sorting issues… depends what you’re willing to put up with, slower framerate or dodgy alpha sorting :stuck_out_tongue:

4

Ah ok, good to know. Looks like my inexperience with mobile GPUs is showing!

Is that pixel clipping in general which is slow for mobile devices?

5

I think so. Something to do with the way it renders the screen in cells of a given pixel dimension, so if there’s a clip shader being rendered anywhere in that cell it has to render the entire cell again, but with alpha test it can carry on as per normal.

Honestly I don’t know the full technical reasons - that’s the explanation I was given and it doesn’t make 100% sense to me! - but some googling should answer it.

6

Thanks for the detailed asnwers… Since the shaders under mobile section didn’t look good in my game, I go with the unlit / transparent cutout. I hope there will be no problems.

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