.Obj exported from Unity3D causes System.IndexOutOfRangeException

[Mirazes]

@Robmaister
When i start example from repo to load .obj and generate navmesh i get IndexOutOfRangeException on file ObjModel.cs line 88: if (!int.TryParse(line[1].Split('/')[2], out n0)) continue;

I'm using obj exporter from http://wiki.unity3d.com/index.php?title=TerrainObjExporter
I can open .obj file generated by exporter inside blender and 3D builder so the format should not be a problem here.

StackTrace

   target SharpNav.Examples.ObjModel..ctor(String path) 
file SharpNav.Examples\ObjModel.cs:rivillä 88

   target SharpNav.Examples.ExampleWindow.LoadLevel() 
file SharpNav.Examples\ExampleWindow.Drawing.cs:rivillä 124

   target SharpNav.Examples.ExampleWindow.OnLoad(EventArgs e) file SharpNav.Examples\ExampleWindow.cs:rivillä 129

   target OpenTK.GameWindow.Run(Double updates_per_second, Double frames_per_second)
   target SharpNav.Examples.Program.Main(String[] args) file 
SharpNav.Examples\Program.cs:rivillä 16

[Mirazes]

I think i have figured out whats the problem here.. exported terrain from unity doesn't have a normal map and that causes ObjModel.cs to crash. I removed normal map from generation and example seems to work now. Also the main error which are pointed on my first message was nasty format error on my exporter.

[Robmaister]

Yeah, the ObjModel class is a bit fragile as it's meant to be part of the example and not a core part of the library.

[Mirazes]

Well i modified ObjModel a bit and i have working project now. You should check out some generic obj reader/writer and implement it to sharpnav as it would boost usage of this project alot.

[Robmaister]

I haven't looked recently, but yes, a model loading library to be used alongside SharpNav would make life a lot easier for people. The SharpNav interface just takes raw geometry, so anything that can put out triangles should work fine.

I would rather not bring on a ton of dependencies to the core of SharpNav for people who don't need model loading (already handled in-engine, or the geometry is generated), and the interfaces are easily separable.

If I had the time or energy, I would start a separate open-source project like this that exclusively did model loading, as that would be useful in a number of places.

[Deepankar1993]

Are there any solution or workaround for this?
I am also getting the same issue using TerrainObjExporter

for me it somewhat seems work by
changing

                                if (!int.TryParse(line[1].Split('/')[2], out n0)) continue;
                                if (!int.TryParse(line[2].Split('/')[2], out n1)) continue;
                                if (!int.TryParse(line[3].Split('/')[2], out n2)) continue;

to

                                if (!int.TryParse(line[1].Split('/')[1], out n0)) continue;
                                if (!int.TryParse(line[2].Split('/')[1], out n1)) continue;
                                if (!int.TryParse(line[3].Split('/')[1], out n2)) continue;

and commenting out

                                norms.Add(tempNorms[n0]);
                                norms.Add(tempNorms[n1]);
                                norms.Add(tempNorms[n2]);

Are there any other way

[Robmaister]

Well with some effort I can generalize ObjLoader to accept models without normals, but do note that SharpNav.Examples is designed to help understand how SharpNav works, not as a tool that should be used in production.

If there were a library that loaded 3d model files into float[] or equivalent, I would just switch to using that instead. If I get a chance I'll generalize this since multiple people have run into the issue, though

[Deepankar1993]

Can you give some info like
how did you make your obj for the example ?
and while comparing the difference on the obj files with the test obj file
1st difference I noticed is
Orginal obj
f 4/1/4 2/2/2 1/3/1 3/4/3

Unity's generated
f 66/66 67/67 2/2

what data the extra value in the originals obj file holds?

[Deepankar1993]

I believe that extra value has something to do with normals
but
I got it working with no changes to the code
Steps :

1. TerrainObjExporter to get the Obj file of the Terrian from Unity (Name it anything you want ie : unityterrian.obj)
2. Open Blender Go to File>Import > Select Wavefront(.obj)
3. Now go to the folder where you saved "unityterrian.obj" and select it and Click "Export OBJ"
   Once your model open
4. This time go to File>Export > Select Wavefront(.obj)
5. Go to the folder you wanna save and Give it a name (ie :: "Nunityterrian.obj")
   Done
   Nunityterrian.obj will work fine with example

Note : As @Robmaister said Example is not intended for Production use

[Robmaister]

The obj file format supports a few ways of binding faces to vertices: https://en.wikipedia.org/wiki/Wavefront_.obj_file#Face_Elements

For simplicity (and since I need normals to draw the mesh with lighting properly) I only supported the last two formats, that is, I'm assuming there will always be two / characters per vertex in a face. Not all files are like this, some can have 0 or 1. (position only, or position + texcoord)

In the case of TerrainObjExport, it was not exporting normals at all - only positions and texcoords. By running it through Blender, you have Blender calculate and export normals with the obj file.