Modifying UV coordinates in the editor problem

Hi,
I've developped a script to be able to modify the UV coordinates of my plane "models" (simple plains with uv coordinates inside a texture alias) based on the scale of the model and an offset.

I've managed to make it work correctly for runtime, but I can't see it in realtime in the editor unless I use the ExecuteInEditMode attribute on my script. The problem is, if I do that, I get errors from the editor (in the console) saying that using MeshFilter.mesh makes the editor leak meshes and I should use MeshFilter.sharedMesh. The thing is, my needs are instance by instance, not for an entire model. And when I use the ExecuteInEditMode, wether I use mesh or sharedMesh, the UV coordinates of my "models" are modified (and kept as the original UVs) each time I hit "Play" and "Stop" and the operations add up to something really out of hand.

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using System.Collections.Generic;
4. using System.Linq;
5.  
6. public class UvAligner : MonoBehaviour {
7.  
8.     List<Vector2> OriginalUvs = new List<Vector2>();
9.  
10.     List<Vector2> alignedUvs = new List<Vector2>();
11.  
12.     Vector3 lastScale = new Vector3();
13.  
14.     public Vector2 UvOffset = new Vector2 ();
15.  
16.     Vector2 LastUvOffset = new Vector2();
17.  
18.     Vector2 minValues = new Vector2();
19.  
20.     // Use this for initialization
21.     void Start () {
22.         OriginalUvs = new List<Vector2> (GetComponent<MeshFilter> ().sharedMesh.uv);
23.         alignedUvs = new List<Vector2>(OriginalUvs.ToArray());
24.         lastScale = new Vector3(1,1,1);
25.         var minX = OriginalUvs.Min (vector => vector.x);
26.         var minY = OriginalUvs.Min (vector => vector.y);
27.         minValues = new Vector2 (minX, minY);
28.     }
29.    
30.     // Update is called once per frame
31.     void Update () {
32.         AlignUvs ();
33.     }
34.  
35.     private void AlignUvs() {
36.         var currentScale = this.transform.localScale;
37.         if (currentScale.x == lastScale.x && currentScale.y == lastScale.y && currentScale.z == lastScale.z &&
38.             LastUvOffset.x == UvOffset.x && LastUvOffset.y == UvOffset.y) {
39.             return;
40.         }
41.         lastScale = currentScale;
42.         LastUvOffset = UvOffset;
43.         for (var i=0; i<OriginalUvs.Count; i++) {
44.             var uv = OriginalUvs [i];
45.             var x = ((uv.x - minValues.x) * lastScale.x) + minValues.x + UvOffset.x;
46.             var y = ((uv.y - minValues.y) * lastScale.z) + minValues.y + UvOffset.y;
47.             alignedUvs [i] = new Vector2 (x, y);
48.         }
49.  
50.         GetComponent<MeshFilter> ().mesh.uv = alignedUvs.ToArray();
51.     }
52. }
53.  

In Start(), I get the sharedMesh UVs to always base on the original ones (or so I thought), the original scale and the original offsets.

On Update, I check if anything has changed, if not, I return. Otherwise, I process the new UVs from the original ones and the current scale and offsets. I set the new UVs to GetComponent<MeshFilter>.mesh.uv.

For some reason, when using prefabs (because my planes must have colliders), it creates meshes instances and I must always use the "reset to prefab" function in the editor. Is there an equivalent in code so I can always reset? Am I doing something wrong?

Thanks a lot.

 

I am not sure, but this sounds like perhaps before you set the new mesh (when running in editor mode), you should Destroy() the old mesh first. This might also be a cause to use DestroyImmediately(), which is a dangerous little function specifically designed (mostly) for use in-editor.

 

Thanks for the answer. I have updated my original post to include the code I'm using. I'm not really sure how I should use the Destroy() and DestroyImmediately() methods. I've tried to destroy the mesh in different parts of this script, but the mesh only disappears and I have to "reset to prefab" again. Using the code in my original post, where should I use Destroy or DestroyImmediate?

Thanks again.

[Edit]
I have uploaded my test project so you can see what I'm trying to achieve and how the script works. Here is the link : https://drive.google.com/file/d/0BwbWwcCjL9EJdmV3YmxtX3RaZ0E/view?usp=sharing

I have commented the line with the ExecuteInEditMode attribute. If you want to see the behavior I am trying to achieve, uncomment it and rebuild (if it's not done automatically), then move the offset or the scale of the planes (grey brick).
[/Edit]

 

So... does anyone have any idea? Thx