Device copy from 2D to 3D texture

Would be nice to have on-device copy from 2D to 3D texture.

You can bind the z-slices of a 3d texture as FBO, and render with 2D texturing to them.

No, that is not what I want.

I want to copy 2D texture into the slice of a 3D texture.

Just copy, no rendering!

You can blitt it and copying with a PBO should work too.