So I'm planning a new portfolio piece, and for it to turn out how I want, I need some help with constraints. There is going to be a star that always faces the camera, and that much I figured out. The problem is I want the star to always be right side up from the cameras POV, so I think there needs to be an additional rotation constraint as well. I don't know how to go about it though. Advice?
Here is how to do it:
Next, add a limit rotation, and tick both axes you wish to lock or limit. Here, I have ticked the X and Y axes thus disabling them, permitting the star to only rotate around the Z axis as it tracks the camera. This of course can be arranged however you need for your specific scene.
This is the result:
Locked Track Constraint
Setup Suzanne akin to a compass needle via the locked track constraint. Suzanne faces the camera (To -Y) and can only rotate on the Z axis (Lock)
If I understand correctly, you want your star to behave as a "billboard". There are lots of tutorials out there, one for example here: https://www.blendernation.com/2019/04/27/how-to-properly-billboard-sprites-particles-in-blender/
This tutorial shows essentially the method also described by @batFINGER, using the "locked track"-constraint.