6 replies to this topic

[TheOrestes]

Hi,

I was trying to understand obj file loading for 3d models. I am referring to DirectX 9.0 sample "MeshFromOBJ" to understand how it has been done. I tried creating a simple cube in Maya2012 & exported to obj file format. I tried replacing default "cup" model from the sample to my newly exported model. Please refer to the screenshot for the output I am getting.



Please also refer to the obj file content which I got after exporting.

[source lang="plain"]# This file uses centimeters as units for non-parametric coordinates.mtllib cube2.mtlg defaultv -0.762213 -0.812331 0.873061v 0.762213 -0.812331 0.873061v -0.762213 0.812331 0.873061v 0.762213 0.812331 0.873061v -0.762213 0.812331 -0.873061v 0.762213 0.812331 -0.873061v -0.762213 -0.812331 -0.873061v 0.762213 -0.812331 -0.873061vt 0.375000 0.000000vt 0.625000 0.000000vt 0.375000 0.250000vt 0.625000 0.250000vt 0.375000 0.500000vt 0.625000 0.500000vt 0.375000 0.750000vt 0.625000 0.750000vt 0.375000 1.000000vt 0.625000 1.000000vt 0.875000 0.000000vt 0.875000 0.250000vt 0.125000 0.000000vt 0.125000 0.250000vn 0.000000 0.000000 1.000000vn 0.000000 0.000000 1.000000vn 0.000000 0.000000 1.000000vn 0.000000 0.000000 1.000000vn 0.000000 1.000000 0.000000vn 0.000000 1.000000 0.000000vn 0.000000 1.000000 0.000000vn 0.000000 1.000000 0.000000vn 0.000000 0.000000 -1.000000vn 0.000000 0.000000 -1.000000vn 0.000000 0.000000 -1.000000vn 0.000000 0.000000 -1.000000vn 0.000000 -1.000000 0.000000vn 0.000000 -1.000000 0.000000vn 0.000000 -1.000000 0.000000vn 0.000000 -1.000000 0.000000vn 1.000000 0.000000 0.000000vn 1.000000 0.000000 0.000000vn 1.000000 0.000000 0.000000vn 1.000000 0.000000 0.000000vn -1.000000 0.000000 0.000000vn -1.000000 0.000000 0.000000vn -1.000000 0.000000 0.000000vn -1.000000 0.000000 0.000000g pCube1usemtl initialShadingGroupf 1/1/1 2/2/2 4/4/3 3/3/4f 3/3/5 4/4/6 6/6/7 5/5/8f 5/5/9 6/6/10 8/8/11 7/7/12f 7/7/13 8/8/14 2/10/15 1/9/16f 2/2/17 8/11/18 6/12/19 4/4/20f 7/13/21 1/1/22 3/3/23 5/14/24[/source]
Is there anything that I am missing or doing wrong while exporting. I used all default settings in the exporter.

Edited by TheOrestes, 07 October 2012 - 08:11 AM.

[Amr0]

The obj loading code that is used in the DX SDK is not that robust - it's meant to be a demonstration, but it will fail when tested with models created from various content authoring tools as you've seen. The official obj loader is the fbx sdk. It's robust, supports more formats than obj, and I think it's the way to go if you don't need to use your own custom format. You'll have to write the code that reads model data in the fbx sdk format and converts it into a D3D-compatible format, but there are samples that show how to do that, so you will not be starting from scratch.

That said, I have written a more robust obj loader and a Direct3D 9 sample that demonstrates its usage. I've tested it with models exported from Maya and zbrush. You can find the loader and the sample on my blog here.

[TheOrestes]

Hey Amro,

Thanks a lot for your reply. I was actually wondering if am missing out something during mesh exporting assuming the code works correctly. I will go through your blog page ( looks interesting ) & Obj loader as well.

Thanks a lot.

[kubera]

For me, this sample project is very good.
The shown problem is depended on CullMode.
You would swap vertices in such triangle for see the correct model.

[TheOrestes]

The shown problem is depended on CullMode.

I tried setting the cullmode to NULL inside shader technique, though i was able to see the backfaces, the graphical glitch remained.
Did you try creating mesh in Maya, exporting it as OBJ & then loading?

[kubera]

I have loaded 3D scans.
I am sorry, I was wrong in this case.

[TheOrestes]

That said, I have written a more robust obj loader and a Direct3D 9 sample that demonstrates its usage. I've tested it with models exported from Maya and zbrush. You can find the loader and the sample on my blog here.

Hi Amr0,

Your code works like a charm. Thanks a lot for sharing it. By the way, I tried making any mesh inside Maya to "Triangulate" first then export. This makes the face data inside OBJ file to vary accustoming triangle indexing. Interestingly, as expected, this triangulated mesh is getting rendered absolutely fine even in DirectX OBJ sample.

Thanks a lot for sharing your code.

Cheers,
TheOrestes.