How do I assign a "_unmanaged" pointer from a managed COM reference?

[maaron]

For context, I'm trying to create a D3D12_RESOURCE_BARRIER struct, which has a field of type ID3D12Resource_unmanaged*. How do I set this field if all I have is a ID3D12Resource?

[AArnott]

Two options:

1. Use fixed on your ID3D12Resource to get a pointer to it. This will not work if the pointer must live longer than your fixed block.
2. Use GCHandle to pin the object for an extended period, and use its AddrOfPinnedObject method.