I just spent two hours trying to figure out why my starfield-with-custom-rendering-code wasn’t rendering unless I put it somewhere which ought to have been behind the camera, and why all the tests for which stars were visible weren’t working correctly.
Completely forgot that the camera transform needs to be supplied to the rendering code, for these custom-rendering entities. It’s not done for you automatically, the way it is with vsSprites and vsModels. :)
I started out planning to steal the starfield from the old Asteroids testbed game. But having looked at it again, it’s only six single-pixel dots. So maybe that’s not ideal for use here. I’m putting in a 3D starfield behind the 2D game, just because it looks nice. :)