First, I thought I exported a geometry wrong when I got the faceted specular on a model. I thought it was the soft edge issue but after I have gone through several tests, I realize that ue4 changes vertex order when it imports geometry regardless of the import option settings. Simple geometry like grid or sphere, ue4 doesn’t change the vertex order but more complex geometry, ue4 changes its vertex order. Let’s say I have a mesh in maya that looks just fine in maya’s viewport. Then when I import it to ue4, I see faceted specular issue. So I export that geometry from ue4 to maya. Then suddenly maya suffers from same rendering issue that ue4 has. Trust me, I have tested all possible cases and I am very confident that this has nothing to do with import / export settings. So just in case, I opened up the "Showdown Cinematic VR " demo scene and applied a very simple material on one of the cars and I see same faceted specular issue that I have seen in my scene. This is a major rendering problem. I posted this issue here. maya to udk 4 and weird rendering artifacts - Rendering - Unreal Engine Forums
I thought I fixed the issue by changing vertex order in maya but that test was done on very simple geometry. When I applied that to more complex geometry, same issue occurred. I don’t see this issue in unity or mari or any other package other than ue4.
While I understand vertex order was a solution for your issue on the forums, the cause of the faceting is the engine reading variations in the model’s tangents and binormals, which correcting the vertex order would have adjust these values as well.
If you take a model which is exhibiting this faceting, like the cars in the Showdown VR Demo, and recalculate Normals and Tangents via the Static Mesh Editor build settings, the faceting will be corrected by the engine itself. You can and should set the Normals and Tangents to always recompile when importing an asset unless you are doing something with an effect in which the normal direction needs to be strictly controlled.
As I said before, it doesn’t matter what options I choose, ue4 changes the vertex order and it won’t correctly display the specular and reflection right. I already tried all build settings. This is something that your engineers need to take a look. I don’t know if you answer my question after checking with your engineer or not but trust me this is a bug and has nothing to do with settings. As I said before, this is not smooth edge issue. Just check with your engineer if there is a chance that ue4 changes the vertex order. If it does, that is the source of this problem. Thank you!
The engine does not change vertex order itself, but it will triangulate the mesh if not pre-triangulated in a Modeling program and in the triangulation process the vertex order will be adjusted based on the triangulation done in the engine. If you can provide an asset in which recompute tangents and normals does not correct this issue, I can go to the engineers, but currently I have no assets which cannot be corrected with the recompute settings.
I made a simple case file and attached here.
Open “sample” in content folder.
It really doesn’t matter what import export options that I choose, it will output pretty much same image. I saw this artifacts on vr demo scene file as well.
