Mesh vertex info per frame

Questions & Answers
1

I have a piece of cloth in my game and I want tot extract the vertex position in each frame. However the numbers in the list do not change. How can I update these positions? In my code I try to access the mesh component of the cloth then extract the vertex positions but it only shows the initial positions and when I hit start the list won’t get updated.

public Vector3[] clothMeshVerts;
    public int numOfVerts;
    Vector3[] normals;
    public int[] trianlges;
    SkinnedMeshRenderer smr;


    void Start()
    {
         smr = GetComponent<SkinnedMeshRenderer>();
     }

    void Update()
    {
        
        clothMeshVerts = smr.sharedMesh.vertices;
        numOfVerts = smr.sharedMesh.vertexCount;
              
    }
2

In the past there was no way to access the current state of a SkinnedMeshRenderer as the skinning happens either on the GPU or in the engine’s core. Of course the sharedMesh it the “unskinned” Mesh or the “source” Mesh.

They now added a way to access the current state of the skinned mesh. You just have to use BakeMesh of your SkinnedMeshRenderer and pass a temp Mesh object which will be “filled” with the current snapshot of the skinned mesh.

Since you want to access the data every frame you might want to re-use that temp Mesh, so don’t create a new one each frame. If you do create a new Mesh, keep in mind that the old one need to be Destroy()-ed or it will hang around in memory and cause a memory leak.

edit

Ahh, ok that’s just another “oddity” of how Unity implements certain things ^^. It seems that BakeMesh doesn’t work with cloth objects. However the Cloth component itself has a “vertices” property which return the current “skinned” vertex positions. I quickly created this script and used a standard plane mesh and it works as intended:

using UnityEngine;

public class ViewClothMesh : MonoBehaviour
{
    Cloth cloth;
    int[] tris;
    void Start ()
    {
        cloth = GetComponent<Cloth>();
        Mesh mesh = GetComponent<SkinnedMeshRenderer>().sharedMesh;
        tris = mesh.triangles;
    }
    
    void Update ()
    {
        var verts = cloth.vertices;
        for(int i = 0; i < tris.Length; i+=3)
        {
            var v1 = transform.TransformPoint(verts[tris[i    ]]);
            var v2 = transform.TransformPoint(verts[tris[i + 1]]);
            var v3 = transform.TransformPoint(verts[tris[i + 2]]);
            Debug.DrawLine(v1, v2);
            Debug.DrawLine(v2, v3);
            Debug.DrawLine(v3, v1);
        }
    }
}

ps: the Cloth component also has a “normals” property in case you need the skinned normals as well.