[Fluxus] load-primitive vs recalc-normals

[David Griffiths]

On Wed, 2011-05-04 at 20:52 +0200, Kassen wrote:
> 
> 
> On 4 May 2011 20:24, David Griffiths <dave at pawfal.org> wrote:
>         Hi Kassen,
>         
>         The OBJ model format is indexed, so when you save a primitive
>         and load
>         it back in it converts it to indexed mode. It's not really
>         possible (or
>         quite "non-trivial") to convert them back into straight arrays
>         again.
> 
> 
> Ah! that explains things.
>  
>         
>         Once you have an indexed mode primitive it becomes ambiguous
>         how to
>         smooth normals, as they may be shared by many different faces.
>         
>         Sorry if this is a bad explanation, will try better if needed.
>         
> 
> 
> No, I get it. Thanks.
> 
> 
> So, in practice this probably means that I can't have smooth looking
> objects that I load from file, right? 

The problem really is recalc-normals - it's a bit of a quick fix
solution, has cases where it won't work, and only acts globally on the
object (i.e. all hard or all smooth edges). It's not meant for more
advanced things.

The idea with the object loading is that they are coming from (eg)
blender, where you can specify smooth/hard transitions properly on an
edge by edge basis. 

Otherwise, for more specific things you can tweak normals manually in
fluxus in any way you like with pdata-map! etc.

cheers,

dave