Here is an example of a problem I have recently noticed:
collision-rotation error example.mfa
When an image that has a transparent border is rotated using "Set angle", even to only multiples of 90 (a situation where, as far as I can tell, the rotation should be pixel-perfect with no blending of pixels), it is sometimes triggering collisions with objects that should be overlapping only fully transparent pixels, which usually do not trigger collisions. The transparent border is necessary to ensure smooth looking edges at every angle, but now it's causing problems of its own.
I know you could work around the problem by having two objects- an invisible one with no transparent border to handle collisions, and another with the transparent border to follow it and provide the visuals- but I still would like to understand this problem more and find out if there are any easier fixes.
I wish I knew what the rotation algorithm was like in general. Because it also causes another problem of an image sliding a couple of pixels when rotating in place when the dimensions of the image are odd (which, if anything, you would think would be more likely to be prevent that issue, since there's a perfect center).
Does anybody have any insight into this?