Export meshes as OBJ

[andburn]

Implemented basic OBJ exporting, works for the unity 4 & 5 bundles I have.

Elements not implemented:

• topology triangles
• compressed meshes
• half-floats (16 bits)

Don't know how widespread these missing features are, but I didn't encounter them.

[andburn]

Updated:

• change string concatenation to list joins
• remove single quotes
• remove Vec4 rgba aliases (not used)
• remove unnecessary temporary variables
• fix possible trailing slash on face definitions, if normals were empty

[andburn]

Updated:

• Comments addressed.
• Make vecX_str methods static (I think they fit better inside the OBJMesh class, as they are specific to the OBJ format).
• Added MeshData class to hold vertex and index info, moved top-level methods into it too.

[jleclanche]

I think they fit better inside the OBJMesh class, as they are specific to the OBJ format

I wouldn't disagree if these were generic vectors but... just call them OBJVector2, OBJVector3 etc and you should be fine.

[andburn]

Ok. One other thing. Its outputting the values to 15 decimal places, does rounding it down to 6-8 seem sensible?

[jleclanche]

We can figure that out another time.

[andburn]

Updated to use __str__

[jleclanche]

Thank you!