Re: 3d file type

[Chris <chris@starforge.co.uk>]

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[Tue, 12 Nov 2002 22:09:34 -0600] Message from Steve Baker:

> The 'MODELLER FORMAT' will probably be something like '.obj' *UNLESS*
> you are lucky enough to own a modeller that supports file I/O
> plugins - in which case, you would probably be well advised to write
> an 'exporter' for a format that holds exactly the information you need 
> as input to your 'model compiler' - and yet is easy to read and write
> so as not to slow down your modelling process.

I agree with everything you say except this paragraph. If your models are
fairly simple, and the modeller supports the features you need just in a
different way than you need in the game, then exporter plugins are fine.
But if you need to include a lot of game-specific information then exporters
may actually make life more complicated. 

To illustrate this, the models in my game can have up to three different
"layers" - one visible from the outside, one that is only visible when
inside (don't ask, long story ;) and a special layer used in certain game
screens. The first layer has up to 8 level of detail stages, the second
layer has two. The format also contains information about which sections can
move and rotate, where specific entities are, how impacts on faces are
mapped to the damage model, where other objects can be joined to the object
and a load of other information. Now I could write an exporter for a modeler
that generates some of this, but I absolutely need a tool to define the
rest - and if I change the game format then I not only have to recompile
bits of the custom tool but also the exporter and make sure everyone using
the exporter has updated both the tool and the exporter to the latest
versions. However, by keeping all the format loading in the tool only the
game format reader and writer in the tool need be updated. Harsh experience
has taught me that keeping the number of things people need to update to
a minimum is the only way to avoid minor disasters each time you change the
file format..

Chris
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