SOFA - Topic: [SOLVED] How to convert obj to msh format file?

Tagged: Gmsh Loading

This topic has 6 replies, 7 voices, and was last updated 5 years ago by Eyad.

Viewing 7 posts - 1 through 7 (of 7 total)

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9 January 2018 at 07:13 #10283
BennyYan
Blocked
How to convert obj to msh format file?
No sample source code about it.
I try to make a ConvertObjToMsh function with MeshObjLoader/MeshExporter class, but it failed to execute.

The source code is as follows:

================================================================
```
#include <sofa /core/objectmodel/SPtr.h>
#include <sofaloader /MeshObjLoader.h>
#include <sofaexporter /MeshExporter.h>
#include <sofa /core/objectmodel/DataFileName.h>

bool ConvertObjToMsh()
{
using sofa::component::loader::MeshObjLoader;
using sofa::core::objectmodel::New;

MeshObjLoader::SPtr loaderFixed = New<meshobjloader>();
loaderFixed->setName(“loader”);
std::string filenameObj = “D:/skull_and_teeth_coarse.obj”;
loaderFixed->setFilename(filenameObj);
bool bResult = loaderFixed->load();
if (!bResult) {
return false;
}

using sofa::component::misc::MeshExporter;

// class BaseLoader : public virtual objectmodel::BaseObjec
MeshExporter::SPtr exp = New<meshexporter>(); //loaderFixed
sofa::core::objectmodel::BaseContext* pContextLoad = loaderFixed->getContext();
sofa::core::objectmodel::BaseContext* pContextExt = exp->getContext();
pContextExt = pContextLoad;
exp->init(); // Execution here failed
exp->writeMesh();
return true;
}
```
How to convert obj to msh format file?
22 November 2018 at 17:00 #12511

Hugo
Keymaster

dear @bennyyan888888

In a simple way, you can load you *.obj mesh in blender, export in *.stl, then load the *.stl in the software gmesh and export a *.msh format.

If you really want to get it automatic in C++, you need to create the two classes (MeshObjLoader, MeshExporter) and specify each Data of the MeshExporter (position, edges, triangles, quads, tetras, hexas) from the loader info.

If you face issue, could you share the error output ?

Note that for mesh format loading and exporting, a project is going on to use the assimp library. Stay tuned.

Best

Hugo

22 November 2018 at 19:47 #12520

Harris
Blocked

Hi @bennyyan888888

The way I convert .obj files into .msh:
1)Convert .obj to .stl in blender or in meshlab
2)Use tetgen to tetrahedralize the surface model.Tetgen make a .mesh file
3)Convert .mesh to .msh in gmsh software

hope this helps,
Harris

24 April 2019 at 15:39 #13431

Zahra
Blocked

Hi,

maybe this is simple question but I’am confused.
I am doing this as @Hugo mentioned: “load *.obj mesh in blender, export in *.stl, then load the *.stl in the software gmesh and export a *.msh format.” but there is some translation and rotation when I load the .obj file in blender. Anybody knows how I can have the exact file without translation and rotation?

Best,
Zahra

11 June 2019 at 07:26 #13620

simon
Blocked

I used MeshLab to convert *.obj to *.stl and then used GMsh to convert *.stl to *.msh. There *.msh format I received is diffent from the *.msh given by Sofa

28 November 2019 at 15:25 #14661

vicky
Blocked

hi Harris,
1. Convert .obj to .stl in blender and import in gmsh {http://gmsh.info/} from gmesh tool exported as mesh-Gmesh MSH(*.msh) .msh . this is not working.

<MeshGmshLoader name=”GmshLoader” filename=”Sphere.msh” />
<Mesh src=”@GmshLoader”/>
<MechanicalObject name=”dofs” scale=”10″ src=”@GmshLoader” />
<TriangularBendingSprings name=”FEM-Bend” stiffness=”300″ damping=”1.0″ />
<TriangleCollisionModel />

error:file’Sphere.msh’ finally appears not to be a Gmsh file

23 December 2019 at 10:40 #15084

Eyad
Blocked

To get a .msh that works with SOFA, I imported a .stl file into gmsh, then exported into a “Mesh – Gmsh MSH (*.msh) format”.
When prompted for the msh options, select “Version 2 ASCII” format, for some reason ticking “select all elements” or not generates the same file for me, it works in both cases. Just don’t tick the “save parametric coordinates” box.

Hope this helps!
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