GetExportFormatDescription gets two same string, how to control different format

[kimkulling]

I hope to control assimp export format.
I use GetExportFormatDescription(index) from 0 to last one and get follow result:
0: dae 1: x 2: stp 3: obj 4: obj 5: stl 6: stl 7: ply 8: ply 9: 3ds 10: gltf 11: glb 12: gltf2 13: assbin 14: assxml 15: x3d 16: 3mf
There are two obj (3,4) and two ply(7,8).
I think that two obj or ply format, maybe one ascii and another one bin.
But how does it control or choose?

aiReturn Assimp::Exporter::Export ( const aiScene * pScene,
  const std::string & pFormatId,
  const std::string & pPath,
  unsigned int pPreprocessing = 0u )

my code as follow:

Assimp::Exporter exporter;
auto numExporters = exporter.GetExportFormatCount();
int index = -1;
for (auto i = 0; i < numExporters; i++) {
  const aiExportFormatDesc format = exporter.GetExportFormatDescription(i);
  TRACE("%d: %s\n", i, format->fileExtension);
  if  (ext.compare(format->fileExtension) == 0)
    index = i;
  }
  if (index == -1)
  {
    AfxMessageBox(L"No support format");
  }
  const aiExportFormatDesc format = exporter.GetExportFormatDescription(index);
  aiReturn ret = exporter.Export(scene, format->id, out);
}

[RichardTea]

The field aiExportFormatDesc.id is supposed to be used to identify the exporter, not the extension.

• See "cexport.h"

This already works just fine - eg to export as Collada, you have to ask for "collada", not "dae".

I see these exporters at the moment:

Id: 'assbin'   Assimp Binary - *.assbin
Id: 'assxml'   Assxml Document - *.assxml
Id: '3ds'      Autodesk 3DS (legacy) - *.3ds
Id: 'fbxa'     Autodesk FBX (ascii) - *.fbx
Id: 'fbx'      Autodesk FBX (binary) - *.fbx
Id: 'collada'  COLLADA - Digital Asset Exchange Schema - *.dae
Id: 'x3d'      Extensible 3D - *.x3d
Id: 'gltf'     GL Transmission Format - *.gltf
Id: 'glb'      GL Transmission Format (binary) - *.glb
Id: 'gltf2'    GL Transmission Format v. 2 - *.gltf
Id: 'glb2'     GL Transmission Format v. 2 (binary) - *.glb
Id: 'ply'      Stanford Polygon Library - *.ply
Id: 'plyb'     Stanford Polygon Library (binary) - *.ply
Id: 'stp'      Step Files - *.stp
Id: 'stl'      Stereolithography - *.stl
Id: 'stlb'     Stereolithography (binary) - *.stl
Id: '3mf'      The 3MF-File-Format - *.3mf
Id: 'obj'      Wavefront OBJ format - *.obj
Id: 'objnomtl' Wavefront OBJ format without material file - *.obj
Id: 'x'        X Files - *.x

All those IDs appear to be unique

[RichardTea]

I'm not certain whether the uniqueness of the format_id is currently enforced though.

[RichardTea]

I think this issue can now be closed, the unit tests added in this commit enforce unique idents.
7e8a3ec#diff-60dd585b361aadf04df9171bb2a8b084