Mesh.AcquireReadOnlyMeshData

Parameters

Returns

MeshDataArray Returns a MeshDataArray containing read-only MeshData structs. See MeshDataArray and MeshData.

Description

Gets a snapshot of Mesh data for read-only access.

When you pass one or more Meshes to Mesh.AcquireReadOnlyMeshData, Unity returns a MeshDataArray of read-only MeshData structs. You can access the resulting MeshDataArray and MeshData structs from any thread. Creating a MeshDataArray has some overhead for memory tracking and safety reasons, so it is more efficient to make a single call to Mesh.AcquireReadOnlyMeshData and request multiple MeshData structs in the same MeshDataArray than it is to make multiple calls to Mesh.AcquireReadOnlyMeshData.

Each MeshData struct contains a read-only snapshot of data for a given Mesh.

You must dispose of the MeshDataArray once you have finished working with it. Calling Mesh.AcquireReadOnlyMeshData does not cause any memory allocations or data copies by default, as long as you dispose of the MeshDataArray before modifying the Mesh. However, if you call Mesh.AcquireReadOnlyMeshData and then modify the Mesh while the MeshDataArray exists, Unity must copy the MeshDataArray into a new memory allocation. In addition to this, if you call Mesh.AcquireReadOnlyMeshData and then modify the Mesh, your modifications are not reflected in the MeshData structs.

This method will throw an InvalidOperationException if isReadable is false for one or more input meshes. When working in the Unity Editor, use MeshUtility.AcquireReadOnlyMeshData to skip this check.

Use Dispose to dispose of the MeshDataArray, or use the C# using pattern to do this automatically:

using Unity.Collections;
using UnityEngine;

public class ExampleScript : MonoBehaviour
{
    void Start()
    {
        var mesh = new Mesh();
        mesh.vertices = new[] {Vector3.one, Vector3.zero};
        using (var dataArray = Mesh.AcquireReadOnlyMeshData(mesh))
        {
            var data = dataArray[0];
            // prints "2"
            Debug.Log(data.vertexCount);
            var gotVertices = new NativeArray<Vector3>(mesh.vertexCount, Allocator.TempJob);
            data.GetVertices(gotVertices);
            // prints "(1.0, 1.0, 1.0)" and "(0.0, 0.0, 0.0)"
            foreach (var v in gotVertices)
                Debug.Log(v);
            gotVertices.Dispose();
        }
    }
}

Additional resources: MeshDataArray, MeshData, AllocateWritableMeshData, ApplyAndDisposeWritableMeshData.