Function gvr_buffer_viewport_get_source_buffer_index

pub unsafe extern "C" fn gvr_buffer_viewport_get_source_buffer_index(
    viewport: *const gvr_buffer_viewport,
) -> i32

Gets the index of the source buffer from which the viewport reads its undistorted pixels.

@param viewport The buffer viewport. @return Index of the source buffer. This corresponds to the index in the list of buffer specs that was passed to gvr_swap_chain_create().