How do I create non-rectangular sprite?

Is it possible to create a non-rectangular sprite object? Like a triangular or circular sprite object?

The bounding box affects how the system perceives an object's shape, the actual shape is a rectangle since that is the simplest shape that makes sense.

Then how do I make circular or eclipse object? The collision polygon only has 4 sides.

You can add more for up to 8 - which is good enough to approximate a circle.

If it's a physics object, you can change the bounding box shape in the physics properties, too (but only to one of a few preset shapes, including a circle; no triangles, tho, iirc).

You can add more for up to 8 - which is good enough to approximate a circle.

How do I add more? When I create a new sprite object the "Add point" is gray out.

You have to click on a previous point and then it will add another in-between. It also, apparently lets you add more than 8, but with a warning message.