Technically you always have an infinite amount of edge due to the ✨coast line paradox✨

ok

It's got its limitations of course. The algorithm that finds the outline of the projection discards any points inside the shape. Therefore every shadow gets turned into a convex collider even if there should be a hole or a indentation in its outline.

The orientation of the receiving plane is reconstructed from the position of the points so you could move and rotate it at runtime if you wanted to.
This also works for multiple objects and light sources without noticeable performance cost.

It works by projecting each vertex of an object (or proxy) onto a "canvas" and then constructing a new collider from the resulting points.

„She’s brilliant! Why didn’t I come up with this? Nobody‘s buying my pre-wetted cereal!“

Yeah, it might have been at hypertalk. thx
Although I did already skip through all of this years talks on YT. I‘ll check again.

Woah. I didn't think the quality would be that bad...