RE: [AD] Patch for the documentation of polygon_z_normal()

["Robert Ohannessian" <ROhannessian@xxxxxxxxxx>]

> Also, do you think that one of the 3D examples needs to use the
> "camera->poly dot normal" method instead of polygon_z_normal()? 

That's probably too difficult for a beginners guide. You can't just do
camera->poly dot normal > 0 and have that work, you need to compare
against a range of values (which can be negative), based on the
projection transform, and clip against that.

If you don't do that, then you need to convert your geometry to
screen-space. In that case, you might as well just use
polygon_z_normal().