Can x1,y1,...x4,y4 describe a bounding that is non-rectangular?

[mimslim]

I want to detect objects that are more wedge shaped, or like a piece of pie. I have created a database or such objects at various sizes and rotations, but my training is failing. Are the bounding box coordinates in yolo5_obb limited to describing only rotated rectangles? Or can they describe a bounding perimeter of any shape constrained by 4 points?