load models

hello,
Can anyone provide a working code for loading one\group of models from .obj .mtl and some .jpg files and rendering them on screen? I was trying to load models, but I cannot load or apply textures, and it gets messy.
I looked at example folder, but it only loads model with no texture.
I'm probably not applying them correctly, but there might be other errors.

I think there is a problem with materials; first I load the model

        model = ModelImporter.Load("filename.obj");
        material = (MaterialGroup)((GeometryModel3D)model.Children[0]).Material;

then return that material:

        this.theMaterial = (MaterialGroup)faceNeutral.getMaterial();

where

                           <GeometryModel3D.Material>
                               <MaterialGroup x:Name="theMaterial">
                                   <DiffuseMaterial>
                                       <DiffuseMaterial.Brush>
                                           <LinearGradientBrush StartPoint="0,0.5" EndPoint="1,0.5">
                                               <LinearGradientBrush.GradientStops>
                                                   <GradientStop Color="LightBlue" Offset="0" />
                                                   <GradientStop Color="LightBlue" Offset="1" />
                                               </LinearGradientBrush.GradientStops>
                                           </LinearGradientBrush>
                                       </DiffuseMaterial.Brush>
                                   </DiffuseMaterial>
                               </MaterialGroup>
                           </GeometryModel3D.Material>

but object still renders as LightBlue.

also number of times I got

//Unable to cast object of type 'System.Windows.Media.Media3D.MaterialGroup' to type 'System.Windows.Media.Media3D.DiffuseMaterial'.

thanks

The casting error is in your code, right? If you want to replace the MaterialGroup with the material from faceNeutral, I think you should change the Material property of the GeometryModel3D instead. If you need to keep the MaterialGroup, try Children.Clear() and Children.Add(faceNeutral.GetMaterial());