# Unable to properly load Blender-exported obj files in FleX

I apply some mesh simplification operations on a mesh in Blender and then use the export function in Blender to save the mesh in an obj file. I then load the modified mesh in FleX to run some simulations. However, FleX gives me the following warning/error:

Face with more than 4 vertices are not supported


Here is the mesh I load in FleX after applying the operations: bus-modified.zip

And here's the mesh before applying the operations: bus-original.zip

I am doing the simulation in the background but I noticed that the simulation is not being done properly (materials go through the shape). So I exported the mesh through FleX and loaded it in Blender to see if the shape is consistent. However, the mesh seems to have lost a lot of vertices and is very inconsistent. Here is what FleX exports: bus-flex.zip

Here is an screen shot of the shape after applying the operations:

And after exporting the object from FleX (it also seems that the shape has been scaled):

This also happens if I just load the mesh in Blender and export it (without applying any operations). So my guess is that FleX cannot handle slightly different obj file formats and that's why this happens. In contrast, the simulation will be fine if I directly load the mesh in FleX. But I need to apply those mesh simplification operations to fix the incorrect Normals before running the simulation. I wonder, am I doing something wrong when loading the obj files in FleX? If not, how can I save the obj files from Blender so that the format is compatible with what FleX expects? Any help would be highly appreciated.

• Does anyone have an opinion on this?
– Amir
Jan 10 '18 at 19:39
• maybe not many people here know or use "FleX" (whatever it is)... Feb 17 '18 at 12:21
• Could it be that you have ngon (more than 4 verts) faces in the mesh, and flex only supports triangles (3) and quads (4)? Feb 17 '18 at 12:43
• @batFINGER Maybe ... . So if that's the case how can I output triangle meshes in Blender?
– Amir
Feb 17 '18 at 16:36
• ngon to tris Feb 17 '18 at 16:56