I would like to project a number of separate 3D meshes onto a 2D plane and create a 2D polygon representing the outline of all the meshes. I would also like to to create multiple 2D polygons if the projection creates separate islands (see blue and green polygons in the image below). I would like to do this so I can use the generated 2D geometry for 2D collision detection.
If anyone knows of an algorithm to do this or even just some better search terms that would be very helpful, thank you!
3D view of the meshes to project:
View of what the 2D polygons would look like when projected from the top (blue and green shapes):