[solved] How correctly use MemCpy, to copy NativeArray <Matrix4x4> to Matrix4x4 []?

I know I asked pretty much same question here
https://forum.unity.com/threads/entity-highlighting-in-jobs-material-uv-atlas-shader.745190/
but I think this question deserves dedicated attention, in own thread.
And since I am such noob using pointers, therefore my question.

So if I got NativeArray <Matrix4x4> or NativeArray <float4x4>, how to copy it to Matrix4x4?
As far I understand, this is called copying native to managed data.
Obviously using 'for loop' works. But is slow for large arrays.
I tried using MemCpy, but at best so far I managing crash Unity

I have noticed that NativeArray <Matrix4x4> has GetUnsafePtr. But even using it, results no avail.

Best I was able to get, is

Code (CSharp):

1. unsafe
2. {
3.     var arrayOfMatrices4x4 = (byte*)  ( UnsafeUtility.SizeOf <Matrix4x4> () * nativeArrayOfMatrices4x4.Length  ) ;              
4.     UnsafeUtility.MemCpy ( arrayOfMatrices4x4, nativeArrayOfMatrices4x4.GetUnsafePtr <Matrix4x4> (), nativeArrayOfMatrices4x4.Length );
5. }

I am pretty sure sure thats wrong. Even if I replace nativeArrayOfMatrices4x4.Length for 1, still got crashes.


Any thoughts on guidance?

 

I think you also need to pin the managed array for the duration of the copy.

 

Doesn't NativeArray have a CopyTo(T[] array) method built in?

 

Oh me daft. Indeed.
And works for what I needed.

Just side question, any functional difference between
CopyTo (T[] array)
and
T[] array = ... ToArray () ?
Both output same, form what I see. Other than that, in first case array size need to be preallocated.

Thx as usual.

 

CopyTo lets you reuse an array so you don't have to keep creating allocations.

 

Ah, good to know. so I will use CopyTo.

 

I am looking to do the same thing, but I have a multidimensional array, not a flat array so I cannot use the NativeArray.Copy methods. Would appreciate any pointers, pardon the pun.

Edit:
Some good data here:
https://forum.unity.com/threads/is-there-a-utility-method-for-faster-copying-of-nativearray.543888/