Optional bytesThe stride, in bytes, between the beginning of each block row and the subsequent block row. Required if there are multiple block rows (i.e. the copy height or depth is more than one block).
Optional offsetThe offset, in bytes, from the beginning of the image data source (such as a GPUImageCopyBuffer#buffer|GPUImageCopyBuffer.buffer) to the start of the image data within that source.
Optional rowsNumber of block rows per single image of the texture. rowsPerImage × bytesPerRow is the stride, in bytes, between the beginning of each image of data and the subsequent image. Required if there are multiple images (i.e. the copy depth is more than one).
A buffer which either contains image data to be copied or will store the image data being copied, depending on the method it is being passed to.