Scripting Setting mesh.uv throws Null Reference Error

I don't see any warnings about uv or uv2 being deprecated, so I'm assuming this is a bug.

Example code:

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4.  
5. [RequireComponent(typeof(MeshFilter))]
6. [RequireComponent(typeof(MeshRenderer))]
7. public class DoPlane : MonoBehaviour
8. {
9.     void Start ()
10.     {
11.         Mesh m = new Mesh();
12.  
13.         m.vertices = new Vector3[]
14.         {
15.             Vector2.zero,
16.             Vector2.right,
17.             Vector2.up,
18.             Vector2.one
19.         };
20.  
21.         m.normals = new Vector3[]
22.         {
23.             Vector3.forward,
24.             Vector3.forward,
25.             Vector3.forward,
26.             Vector3.forward
27.         };
28.  
29.         m.triangles = new int[] { 0, 1, 2, 1, 3, 2 };
30.  
31.         // NullReferenceException: Object reference not set to an instance of an object
32.         // UnityEngine.Mesh.SetArrayForChannel[Vector2] (InternalShaderChannel channel, UnityEngine.Vector2[] values) (at C:/buildslave/unity/build/Runtime/Export/Mesh.cs:82)
33.         // UnityEngine.Mesh.set_uv2 (UnityEngine.Vector2[] value) (at C:/buildslave/unity/build/Runtime/Export/Mesh.cs:117)
34.         // DoPlane.Start () (at Assets/DoPlane.cs:32)
35.         //
36.         // at this line
37.         m.uv = new Vector2[]
38.         {
39.             Vector2.zero,
40.             Vector2.right,
41.             Vector2.up,
42.             Vector2.one
43.         };
44.  
45.         m.uv2 = null;
46.  
47.         GetComponent<MeshFilter>().sharedMesh = m;
48.     }
49. }
50.  

 

In this example it doesn't make sense, but with the plugin I work on I regularly rebuild the positions and uv arrays which throws uv2 out of sync. As an optimization I don't clear the entire mesh unless the vertex count changes (because some of the mesh properties aren't cached, they would need to be recalculated which can be heavy). Leaving uv2 intact can look bad if lightmaps were baked to an object, so hence setting null.

As an aside, I really like the way UVs are implemented now. Access to 3 additional vec4 channels is awesome

 

https://fogbugz.unity3d.com/default.asp?757963_0tmnjv1kk7s09g13

 

Awesome, thanks Alexey!