Included in the attached zip is some pictures of a lighting/smoothing anomaly I am seeing in UE3.
Each example’s left side model has triangulation in which all diagonal
edges are parallel to each other. This is making apparent what
appears to be some strange shading interpolation across the shared
edge of coplanar triangles.
Each example’s right side model has a winding triangulation on the
diagonal shared edges of the coplanar triangles, which is eliminating
the issue.
If anyone could provide some insight into why this is happening, I would appreciate it.
This seems like something common that could almost be replicated in Max with how real time lighting renders a light’s inverse decay. In the preview you’ll certainly see these types of artifacts as there’s only one apparent omni light source, but try dropping the sucker in a room with multiple lights and see if it’s the same scenario. I personally have never had any issue with my triangulation of smoothed objects and think it’s just a common issue with smoothing and having an object render with one source light.
Test something similar in a Max scene with an omni light right near the top center of the middle face and set the decay to inverse (similar to UE3’s falloff) and turn the triangles.
I tried your suggestion with the light but was unable to replicate the result in max with their standard material.
More specifically the problem appears to only happen on back faces to the light/s. So assuming there is a shadow then the artifact would not be visible.
So I believe you are right about it being the way the lighting is done, and after all it seems this would be rare to see in a real world game environment.
Just thought I’d chime in and say it’s very similar to what Eric said. I recently just added a ton of static meshes into the scene and was getting tons of those errors that seemed like they were smoothing/triangulation ones. I noticed the default material also had a ton of stretching in the same areas as the lighting issues occured, so I threw a quick flatten map on the assets (as they were not unwrapped yet) and the problem completely went away. I’m sure if you applied an actual texture to those assets you’d see the same issues with the flow in the current UV as you are getting with the lights.
Why this didn’t come to my attention thinking about per pixel or vertex lighting right away I’ll never know…