t > 0 && (
        all(id == vec3u(0u))    // start of buffer
        || (id.x == 0 && (!readPreviousRow      // start of non-compact row
            || (id.y == 0 && !isCompactImage)   // start of non-compact image
        )));
let readDstBufAtEnd: bool = coordE.x >= srcBoundary.x;