assimp cannot read simple obj file

[pca006132]

I finished implementing a simple mesh dump for debugging, but apparently assimp cannot import the simple obj file properly...

For example, for the following obj file (note that vertex indices start from 1 in obj file):

v 5248.20561383250333165051415563 -20170.0219117954256944358348846 4599.79468714238464599475264549
v 5250.17329241749666834948584437 -20170.2593382045743055641651154 4599.52660192011535400524735451
v 5254.53032086375333165051415563 -19987.1410524204256944358348846 4484.25025354863464599475264549
v 5256.49799944874666834948584437 -19987.3784788295743055641651154 4483.98216832636535400524735451
v 5268.75395367625333165051415563 -20040.4808961704256944358348846 4635.88794886113464599475264549
v 5270.72163226124666834948584437 -20040.7183225795743055641651154 4635.61986363886535400524735451
f 4 2 1
f 1 2 6
f 1 3 4
f 3 1 5
f 2 4 6
f 6 5 1
f 4 3 5
f 5 6 4

Reading it with assimp via MeshIO, with debug information added:

  std::cout << "mNumMeshes: " << scene->mNumMeshes << std::endl;
  for (size_t i = 0; i < scene->mNumMeshes; ++i) {
    const aiMesh* mesh_i = scene->mMeshes[i];
    std::cout << "mNumVertices: " << mesh_i->mNumVertices << std::endl;

shows mNumMeshes: 1 and mNumVertices: 24, and this causes the import to fail...

Wondering if there is a simpler way without the need of writing a simple parser for obj files.

@elalish

[elalish]

Yeah, I'm not especially thrilled with Assimp, though this is even worse. Should we consider https://github.com/3MFConsortium/lib3mf?

[PaddiM]

Fresh checkout of assimp - could convert your sample without problems from OBJ to STL via assimp command.

[pca006132]

Just checked, it seems that assimp requires cleanup on the imported mesh even when using the OBJ format which is already an indexed format... weird

[pca006132]

No idea how to enable reading double precision float though, there is such an option but I have no idea how to enable it, and probably easier at this point to just write my own parser...

[PaddiM]

Can you show me your call for aiImportFile? I think setting the postprocessing flags to zero can help.

[pca006132]

It probably doesn't matter too much now considering I am implementing it in #1104. Not as powerful as assimp, not spec compliant, but good enough for debug use.