UE4 POM Cost

Maximum-Dev

Hello,

I'm working on a little thingy here currently with tessellation:



But for performance reasons I'm switching to POM instead.

My material consists of 4 layers and without tessellation or POM it's about 200 instructions which is perfectly fine.
My issue is a single POM node linked to 1 Diffuse and 1 Normal map simply adds up about another 100 instructions to my material. Is this amount normal?

I also tried to limit the POM appearance distance to like even a 1 meter radius from player but the cost stays the same as if it was being rendered on the entire landscape.

Just felt like checking to see if this behavior is normal and or if there are anything to do to further optimize POM. I remember having +10 layers with POM in Cryengine without any issues so I think there are a few things that can be done in UE4 too.

Thanks.

Vailias

Don't worry about instruction count that much. Worry about FPS and actual performance.
The very nature of POM will add a lot of instructions because it has to sample through a lot of layers. 

Link for performance profiling: https://docs.unrealengine.com/latest/INT/Engine/Performance/

Maximum-Dev

With 2 layers having POM I get around 420 instructions and shader complexity turns red. And unfortunately it affects the performance quite a lot.

Simmo

I'm using tessellation in my project as well, and I found this really useful to control the performance hit:

http://oliverm-h.blogspot.com.au/2014/03/ue4-manual-distance-based-tessellation.html

Depending on what works for you, you can set the tessellation distance and transition to low values. I have mine set to 256 and 128, also I lerp to 0 tessellation multiplier. In my case it's barely noticeable and since only things close to the camera get tessellated the performance increase is much lower than using the built in adaptive tessellation. Might be worth a try and play around with different settings!

Tetranome

Thanks for that Simmo ^_^