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After careful consideration to use middleware, I have decided on creating my own 3d file format format to export meshes from 3D authoring application (Softimage) into my game.

I will need to export the following:

  • Vertices
  • Indices
  • Normals
  • UVs
  • Material Information
  • Animation information (no clue, how to import it)
  • Collision mesh
  • Game Properties defined within 3D authoring tool (object intelligence, aggressivity, etc..)
  • ..another assets..

Can I kindly ask for a hint, how to construct my custom file format. How to organize data within my files, please? Does anoybody have a good adivce on exporting animation information, especially when the mesh changes its geometry?

I would be thankful for advices that could point me into right direction. It would be nice to save some time instead of wasting it on incorrect approaches.

I use Softimage as my 3D authoring tool. Target platform is OpenGL ES 2.0 running on mobile devices (iOS, Android). Programming language: C++.

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  • \$\begingroup\$ Personally it seems like you're going in the reverse order. Figure out what your engine needs (and how it's organized), and then just put that data in a file format. \$\endgroup\$
    – Tetrad
    Apr 29, 2011 at 20:32
  • \$\begingroup\$ @Tetrad: Thanks for your comment. I have already created the core of my game, so it is basically up to me, how I decide to format the data. I will have to write file importer in my game as well. \$\endgroup\$ Apr 29, 2011 at 20:35
  • \$\begingroup\$ What sort of animation are you doing? Keyframed mesh interpolation (one new mesh per animation frame), or keyframed skeletal animation (mesh with vertex weights, bones, etc.)? \$\endgroup\$
    – ChrisE
    Apr 29, 2011 at 20:58
  • \$\begingroup\$ What sort of collision meshes do you need? Actual meshes, or can you fake it with a cylinder, or what? \$\endgroup\$
    – ChrisE
    Apr 29, 2011 at 20:59
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    \$\begingroup\$ I don't mean to be mean--I'm just trying to figure out the bare minimum subset you need for what you are doing. I've done a (pretty fast) binary static mesh format, and some of these questions let us simplify your problem space. Also, you don't mind writing a tool to handle import to your format, do you? If you don't, that also significantly simplifies your issue--you can just use AssImp to digest whatever Softimage puts out, and convert to your own file format (would suggest this, in fact). \$\endgroup\$
    – ChrisE
    Apr 29, 2011 at 21:01

1 Answer 1

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Because, I haven't received any answer so far, to provide you with some solution, let me tell you how I solved it.

In the beginning, I use text file format. It is easier to read and debug my application. The text format is based on WaveFront .obj file architecture, and I simply add the tags, as needed.

When I have complete text file format, I will create binary format, that will reflect the data stored directly in my application, so I will minimize the need for parsing, to make the format as fast as possible.

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  • \$\begingroup\$ Am I missing something, but couldn't you just save to a binary format and just adjust your loading algorithm (thus much faster load/read times)? \$\endgroup\$ May 18, 2011 at 10:27
  • \$\begingroup\$ @The Communist Duck It's usually much better to save in a interchange format that can be reopened again in your DCC app, and then compile it to a app specific format. This will reduce a lot of engine/game code and you will have a lot foster loading since you don't have to translate data or change layout. \$\endgroup\$
    – void
    May 18, 2011 at 10:58
  • \$\begingroup\$ @The Communist Duck: The reasons that led me toward text file format firstly were my skills level. I needed to see what data gets exported from 3D authoring application. When sloving bugs, I needed to quickly edit and change data in the file, to search for the causes of problems. If I go with binary file format from beginning, I thought, things would be too messy for me to progress quickly. \$\endgroup\$ May 18, 2011 at 13:28

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