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Old 18th December 2010, 12:42 PM   #1
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Default AC3D File Format

I'm writing a program that translates datcom input files into 3d geometry and outputs that geometry in ac3d format. http://gitorious.org/datcom-modeler/

I read http://www.inivis.com/ac3d/man/ac3dfileformat.html and it left me with some questions:

- crease is not documented.

- I assume the trailing newline excluded from the length of the datablock?

- texrep %f %f is it really floats? what do the values mean?

- What exactly do the OBJECT types world, group and poly mean?
-- is world allowed to have blocks besides kids %d?
-- are group and world just polys with no surface and vertex information?
-- can world and group have data? url?

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Old 23rd December 2010, 06:32 PM   #2
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Default Re: AC3D File Format

Crease determines the point at which vertex lighting normals include/exclude neighboring surfaces from their calculation. If the angle between two surfaces is greater than the crease angle, the surface normals for those surfaces will both contribute to the vertex normal used for lighting a shared vertex.

texrep - yes, really floats. In OpenGL, use these as parameters to glScale2f( a,b ) with the matrix mode set to texture. Should get you the right effect.

world is just the top-level node in the object hierarchy. group is a node which can contain other groups or objects. Neither world nor group shoudl define polys. Objects (can) contain polys. Objects can exist at any level of the hierarchy and can represent lights or objects such as you would manipulate in 'object' mode in the AC3D editor.

world: I do not recall clearly, but I think kids is all to expect in world.

world data/url: not sure.
group data: should work.
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