Die with mesh collider

hi
i have created a 3d die (d8) model in Blender,
i want do detect witch side (or face) is up,i also added a mesh collider to the game object, so i am using a ray cast like so

Code (CSharp):

1. ray = new Ray((transform.position + new Vector3(0, 15, 0)), -Vector3.up);
2.         //ray = new Ray(transform.position, ts.position);
3.         RaycastHit hit;
4.  
5.         if (Physics.Raycast(ray, out hit))
6.         {
7.             if (hit.transform.tag != "die")
8.             {
9.              
10.                 return;
11.             }
12.            
13.             Debug.DrawLine(ray.origin, hit.point,Color.black);
14.             Debug.Log(hit.triangleIndex + "  hit.textureCoord=" + hit.textureCoord);
15.             Debug.Log(hit.transform.tag);
16.  
17.         }

this is working fine, but when i add a rigidbody and mark the mesh collider as Convex i get
hit.triangleIndex=-1
hit.textureCoord=(0,0,0)

can some one explain to me way?
and how i can over come this problem?

 

You mean a dice?

 

Yes

 

RaycastHit.textureCoord doesn't work if the meshcollider is set to convex. Which sucks when you are trying to detect the texture on a physics object, since you can't use non-convex colliders in that case.