Nicolas Alvarez wrote:

>> Gilles Tran <gitran_nospam_@wanadoo.fr> wrote:
>>> AFAIK, instantiation is not a property of the file format, but a 
>>> feature of the renderer.
>>
>>   If you tell the renderer "copy this mesh 1000 times over the scene" 
>> (but
>> the mesh data is kept only once in memory), thus getting a nice scene, 
>> and
>> then you want to save this scene into a file, how do you do that if the
>> file format doesn't support saying "copy this mesh here" commands?
>>
> 
> Keeping it only once in memory is a feature of the renderer, which 
> requires such a command on the file format. Having the triangle list 
> only once in the input file is a feature of the file format. A (quite) 
> stupid parser could duplicate data in memory even if it's not duplicated 
> on the file!

Basically I like the idea of having the flexibility of being able to 
export to a fairly universal format like .obj.   But if .obj doesn't 
support instantiation, and if my model is (or will be) a collection of 
tens if not (perhaps) hundreds of thousands of non-unique meshes (save 
the for transformation of each), then man oh man will that be a big 
file.  I can't imagine most file formats would leave out such a basic 
thing.

Anyway unless somebody can answer somewhat definitively about a good 
format, it looks like I've got some studying to do.  Paul Bourke's page 
that Vincent linked to looks useful especially with that handy search 
button.

Charles

Post a reply to this message