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Re: [Gnu3dkit-dev] 3D file formats

From: Matt Brandt
Subject: Re: [Gnu3dkit-dev] 3D file formats
Date: Mon, 30 Sep 2002 21:00:21 -0500

On Monday, September 30, 2002, at 02:01 PM, Philippe C.D. Robert wrote:


On Sunday, September 29, 2002, at 08:13 PM, Matt Brandt wrote:
I guess I would lean toward something halfway between a bunch of reader/writer classes and a database. It seems to me like the scene graph really is the database, but we might need to add a little bit of information to make things more explicit. Named nodes would be the main thing I can think of, so that a scene object could be reused without a great deal of work. If we try to get into the idea of merging nodes I think we can end up breaking things inadvertently. In some scenes an object might seem like a static object most of the time and just need to be dynamic for one thing. Only the creator will know for sure. Optimizations like that can be left up to the program that creates the scene (or the person).

I agree that a database should mainly be used to serve as a clean import/export interface. But I can imagine some sort of optimisations which can be done on that level, ie. when optimising for a specific target rendering device.

What do you mean by 'named nodes'? You already can name G3DGraphNodes, can't you?

Probably, you'll have to forgive my lack of fluency in the current design. I'm thinking of a facility to attach a name to a scene during import so that it can be used multiple times. It doesn't have to be symbolic, but that seems the most general case. If such a facility already exists then all the better...

I lean toward doing a protocol for a reader/writer and then implementing the file formats separately without an intermediate format.

My first design proposal is more influenced by the NSImageRep class cluster, thus every concrete reader/writer is a subclass of the G3DDatabase but has to implement only the scene format specific code.

I think the NSImageRep cluster is a pretty good model to go with. How about "G3DSceneRep" instead of "G3DDatabase" to make the model and purpose clearer?


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