Quote Originally Posted by Sensei View Post
Have Polygon Statistics window all the time open.
When n-gon (> 4 vertex polygon) is made, you will see, if it's caused by it.
OpenGL is calculating normal vector of polygon from 1st, 2nd and the last vertex of polygon.
If two points share the same position, delta between them is 0, and normal is also 0,0,0.
Which disallows properly shade such polygon.
5-gon with two points positions shared looks to human as 4 point polygon.
LW renderer prior rendering converts everything to triangles, so it often disappears during rendering.
Even if we accept that LW can't be fixed to not make such "junk" in the first place (which isn't the case, but let's presume it is), it would be fairly trivial for LW to occasionally scan through the poly definitions for "coincident vertices", and when the same poly has em within a nano-margin, just merge them (or at least offer to do so). Make the cleaning a pref that comes enabled, but can be disabled in case some hermit up on a mountain requires those to exist for their workflow.

The real answer is to be more diligent about detecting and queuing junk geometry for later inspection/merging during tools' operations (with tool context, so the inspection can log context of generation as well as potentially remove, to isolate "problem tools"). Unfortunately it appears that kind of defensive coding is apparently inconceivable, so having something hanging off the event loop that periodically scans/cleans such cruft would be a fine alternative answer.