[R] RGL 'front' upwards default in rendering image

[Duncan Murdoch]

Joe Byers wrote:
> The documentation for surface3d and rgl.surface in the package RGL states
> "'surface3d' always draws the surface with the `front' upwards
>       (i.e. towards higher 'z' values).  This can be used to render the
>       top and bottom differently; see 'rgl.material' and the example
>       below."
>
> Is there a way to override this default?  I have search all the related 
> methods help and the documents on RGL's website.
There are lots of ways to override it:  as the docs say, rgl.surface is 
more flexible than surface3d, and you can draw triangles or quads 
arbitrarily.  What sort of thing do you want to do?

Duncan Murdoch