Strange result from specific configuration: Perspective Camera + Normal Map + Rotated Sprite

Figured I'd post about this in case anyone else runs into the same issue. Took me a couple hours to figure out what was going on here I'm not sure if its a bug or not.

The issue:
The normalmap for this Player character would become 'offset' seemingly randomly:




The setup:
1) Project is using a Perspective camera (so we can parallax easily).
2) A Light2D as Point Light with Use Normal Map selected (its positioned near the Player's feet in the screenshot)
2) A big grass-sprite that is underneath the Player. It is rotated on the X-axis.
3) The Player character who has a normal-map on top of the grass. Nothing rotated or anything abnormal with this.



I had accidentally rotated the grass-sprite beneath the character. If you are using a Perspective camera, with the 2D Lights, with Normal Maps, then rotating a sprite on the X or Y axis causes the normal-map to become offset/skewed. Here is the Frame Debugger at the step where the rotated-grass sprite was drawn:



Another thing worth noting is that a similar behavior (normal-maps becoming 'offset') happens if your Perspective Camera itself rotates on the X or Y axis. I don't imagine anyone should be rotating the camera like that for a 2D game, but just wanted to mention it - if you accidentally let the camera get rotated even a little bit, everything with the Lights will get out of whack (at least if you're using normal-maps).

Hoping that the "Use Normal Map" part of the 2D Lights system gets a little TLC - there are a couple weird behaviours with it, such as the "Distance" value affecting falloff, etc.