Programmer here: So I've got some procedurally generated geometry, and because I suck at BSPs the mesh geometry is absolute shit. When I render said shitty mesh (in three.js) I get these artifacts in my shadows. My retarded question is: What exactly is causing these? The polys are perfectly parallel, but the shadows are breaking up in weird ways. Any explanation as to why?
Wait, those aren't shadow artefacts, they're just shading.
Is this what you guys call "pinching"?
What generated the geometry? What is it being rendered in? What are the settings for the normal smoothing/edge hardness/smoothing groups? What kind of lighting is it? Show us a wireframe of the meshes.
You have not provided enough information.
that is way too little information to say anything. Generally geometry does not affect what your shading looks like much if you use per-pixel lighting, as opposed to per-vertex lighting. If you use per-vertex lighting, you need to reconsider joining the rest of us in the 21st century.
That being said, there are still a bunch of issues that can happen when you have really ill-behaved geometry or shaders (e.g. flat interpolation between vertex attributes, bad normals, ...)