Dx11 Tessellation Broken in 4.2, completely and totally broken

[Rama]

Dear Friends at Epic,

Tessellation appears to be totally broken in 4.2

Remember the earlier post someone had with dx11 tessellation in their landscapes and spikes appeared everywhere?

And they narrowed it down to the tessellation

Landscape Spikes Due to Tessellation

Why am I seeing problems with Landscape Spikes?

well

I am getting those spikes on my character model!

I am using PN_Triangles with adaptive tessellation enabled

And

my character’s spikes go nuts the closer I get to them!

#Adaptive Tessellation Issue is Distance Related

The closer I get to the character, the more the spikes go bonkers!

#Material

It’s simple, no displacement at all, just Tessellation Factor of 1, for the PN_Triangle smoothing

#Far Away

#Closer

#Closest

(see first comment)

#Summary

The closer the camera gets to my character with the spike tessellation material applied, the more the spikes distort.

I have no displacement on this material at all.

#Non-Adaptive Measurable Just by Tess Factor

If you disable adaptive tessellation and use any value higher than 1, then all the crazyness starts that I’ve never seen ever before 4.2

#Non-Adaptive Tessellation of 1.5

(see second comment)

#This is a Very Big Problem

I have to completely disable my use of Dx11 tessellation until this is fixed or I can’t even see my character in the ocean of bugged tessellation vertex positions that ensues.

[Rama]

#Closest

[Rama]

#Non-Adaptive Tess 1.5

PN_Triangles with tess factor 1.5, non-adaptive

[Lovecraft_K]

Hi -

Okay, first the landscape post that you reference is a limitation of the engine, tessellation cannot be used on landscape materials. Tessellation is always distance based as well, the engine has a built in a way of allowing the tessellation to LOD correctly based on the camera’s distance from the object, which is causing the error to become worse with distance because you are getting more triangles as you get closer to the character.

PN Triangle Tessellation smooths the object, but it does require smoothing groups to be set up ahead of time. So that would be the first thing I would ask you look at to ensure that your smoothing groups are set up correctly and importing correctly. Moreover, if you are not using any displacement, I would absolutely suggest that you add smoothing via the character’s model and not through tessellation in the material. That’s adding unnecessary triangles to your character that you probably will not need to get the smoothing results you could in a modeling program.

Could you give me a screenshot of your character’s wireframe and the material setup?

Thanks

Eric Ketchum

[Rama]

All of your info is helpful Eric but does not address the elephant in my original post

#Why did this never happen in Beta 3 through 4.1.1 and it is happening now?

That’s what I want to know

what changed, and why did it change, and is it a bug?

PS: working on getting you a screen shot

[Rama]

#My Material and Pics

Dear Eric,

I made a utterly simple Tessellation Material test, Tessellation is definitely broken (never happened in Beta3 to 4.1.1 with exact same character model, smoothing groups, and everything)

#Utterly Simple Material Test

PN_Triangles With Adaptive

[Rama]

#Pics of Results

#Far

#Close

[HypnoticShark]

Hello,

I can confirm that I am noticing the same issues as . Tessellation worked fine for me in 4.1.1 and is now broken in 4.2.

[HypnoticShark]

I just reimported the model and recompiled all my shaders and the issue seems to be gone

[Rama]

#Take This Very Seriously Please

I need you to take me very seriously here

I’ve been playing with Dx11 tessellation in UE4 since Beta3, and have been a huge fan of it!

This is the FIRST time I have seen this behavior

It is not my model, or at least my model worked fine until 4.2

#Something is wrong with Tessellation in 4.2

[Shadowriver]

Tellesation is not just dx11 ; p small note

[Rama]

Glad you got it working!

#New Import Did Not Work

I just did a completely new import (not a re import) and nothing has improved

[Rama]

#I checked My Smooth Groups Not a Fix

Dear Eric,

I reimported my model after re applying my smoothing groups, smoothing groups is checked during import, and still the issue persists exactly the same

#I can see my smooth groups

I am using my mesh daily and I know the smoothing groups are working cause on non-tess materials the spikes look great / smoothed!

#Max 2013

Is the fact that I am using 3ds Max 2013 possibly an issue? Older FBX file format issues?

Did 4.2 change the way FBX is handled at all, older to newer versions?

[Lovecraft_K]

Hey -

We always take any question asked seriously, but I wanted to eliminate the easier answer before I start looking for the harder one. I would much rather have found a simple fix that one small tweak would solve your issue.

In the meantime though, we actually have found this bug and were able to reproduce it. The bug actually traces back to before 4.1.0 though it does seem to have gotten much worse in 4.2.

Thank you for helping us track this down, but I want to confirm one thing about your character setup to see if it is matching how we had to reproduce the bug here in house, and HypnoticShark also, if you could. Do you do any sort of scaling to the character model and does that make the error worse, better, no different?

Thank You

Eric Ketchum

[Rama]

Dear Eric,

" but I wanted to eliminate the easier answer before I start looking for the harder one."

ahh okay

" The bug actually traces back to before 4.1.0 though it does seem to have gotten much worse in 4.2."

Oooh glad I helped you find it!

#Scaling IS the Bug!

" Do you do any sort of scaling to the character model and does that make the error worse, better, no different?"

Dear Eric,

When I use a static mesh actor that I drag into the world, using the simple material posted in this thread

with a Tessellation factor of 20 (yes I know that’s huge!!!

#Without Scaling

There is absolutely no distortion!

#You found the source of the bug!

Yaaaay!

#

[HypnoticShark]

My model is scaled but recompiling shaders and reimporting the model fixed it for me. Good to know you found the source of bug! My model is scaled in scene (not through the build settings in the static mesh editor) if that helps

[Rama]

#Final Proof of the Bug We Found

We found it!!!

Scaling of 2.781 was sufficient to case distorting even in the component viewer UWorld

[Lovecraft_K]

Hey guys -

Thanks for your help just wanted to confirm that scaling is involved in your issues. We are working on a fix, but I do not have an ETA for it just yet.

Thanks Again -

Eric Ketchum

[Rama]

alright thanks, do keep us posted!

Have fun today!