Funnel Algorithm Unwrap

Could someone explain the benefit of unwrapping a set of triangles to the 2D plane for the funnel algorithm, over not unwrapping them. How does unwrapping actually affect the funnel algorithm? Should it not work in 3D space?


This is primarily useful when the world has a curved surface. For example a spherical world.
For mostly planar worlds it doesn’t make much of a difference.
It is required for 2D games though because otherwise it will assume the funnel lies in the XZ plane, which is not very accurate in that case.

The funnel algorithm is inherently 2D, so it is possible to disable the unwrapping to gain a bit of performance if you know the funnel lies mostly in XZ space.