def copyBlocksFromIter(destLevel, sourceLevel, sourceBox, destinationPoint, blocksToCopy=None, entities=True,
                       create=False, biomes=False, tileTicks=True, staticCommands=False, moveSpawnerPos=False, regenerateUUID=False, first=False, cancelCommandBlockOffset=False):
    """ copy blocks between two infinite levels by looping through the
    destination's chunks. make a sub-box of the source level for each chunk
    and copy block and entities in the sub box to the dest chunk."""

    (lx, ly, lz) = sourceBox.size

    sourceBox, destinationPoint = adjustCopyParameters(destLevel, sourceLevel, sourceBox, destinationPoint)
    # needs work xxx
    log.info(u"Copying {0} blocks from {1} to {2}".format(ly * lz * lx, sourceBox, destinationPoint))
    startTime = datetime.now()

    destBox = BoundingBox(destinationPoint, sourceBox.size)
    chunkCount = destBox.chunkCount
    i = 0
    e = 0
    t = 0
    tt = 0
    sourceMask = sourceMaskFunc(blocksToCopy)

    copyOffset = [d - s for s, d in zip(sourceBox.origin, destinationPoint)]

    # Visit each chunk in the destination area.
    # Get the region of the source area corresponding to that chunk
    #   Visit each chunk of the region of the source area
    #     Get the slices of the destination chunk
    #     Get the slices of the source chunk
    #     Copy blocks and data

    for destCpos in destBox.chunkPositions:
        cx, cz = destCpos

        destChunkBox = BoundingBox((cx << 4, 0, cz << 4), (16, destLevel.Height, 16)).intersect(destBox)
        destChunkBoxInSourceLevel = BoundingBox([d - o for o, d in zip(copyOffset, destChunkBox.origin)],
                                                destChunkBox.size)

        if not destLevel.containsChunk(*destCpos):
            if create and any(sourceLevel.containsChunk(*c) for c in destChunkBoxInSourceLevel.chunkPositions):
                # Only create chunks in the destination level if the source level has chunks covering them.
                destLevel.createChunk(*destCpos)
            else:
                continue

        destChunk = destLevel.getChunk(*destCpos)

        i += 1
        yield (i, chunkCount)
        if i % 100 == 0:
            log.info("Chunk {0}...".format(i))

        for srcCpos in destChunkBoxInSourceLevel.chunkPositions:
            if not sourceLevel.containsChunk(*srcCpos):
                continue

            sourceChunk = sourceLevel.getChunk(*srcCpos)

            sourceChunkBox, sourceSlices = sourceChunk.getChunkSlicesForBox(destChunkBoxInSourceLevel)
            if sourceChunkBox.volume == 0:
                continue

            sourceChunkBoxInDestLevel = BoundingBox([d + o for o, d in zip(copyOffset, sourceChunkBox.origin)],
                                                    sourceChunkBox.size)

            _, destSlices = destChunk.getChunkSlicesForBox(sourceChunkBoxInDestLevel)

            sourceBlocks = sourceChunk.Blocks[sourceSlices]
            sourceData = sourceChunk.Data[sourceSlices]

            mask = sourceMask(sourceBlocks)
            convertedSourceBlocks, convertedSourceData = convertBlocks(destLevel, sourceLevel, sourceBlocks, sourceData)

            destChunk.Blocks[destSlices][mask] = convertedSourceBlocks[mask]
            if convertedSourceData is not None:
                destChunk.Data[destSlices][mask] = convertedSourceData[mask]

            def copy(p):
                return p in sourceChunkBoxInDestLevel and (blocksToCopy is None or mask[
                    int(p[0] - sourceChunkBoxInDestLevel.minx),
                    int(p[2] - sourceChunkBoxInDestLevel.minz),
                    int(p[1] - sourceChunkBoxInDestLevel.miny),
                ])

            if entities:
                destChunk.removeEntities(copy)

                ents = sourceChunk.getEntitiesInBox(destChunkBoxInSourceLevel)
                e += len(ents)
                for entityTag in ents:
                    eTag = Entity.copyWithOffset(entityTag, copyOffset, regenerateUUID)
                    destLevel.addEntity(eTag)

            destChunk.removeTileEntities(copy)

            tileEntities = sourceChunk.getTileEntitiesInBox(destChunkBoxInSourceLevel)
            t += len(tileEntities)
            for tileEntityTag in tileEntities:
                eTag = TileEntity.copyWithOffset(tileEntityTag, copyOffset, staticCommands, moveSpawnerPos, first, cancelCommandBlockOffset)
                destLevel.addTileEntity(eTag)

            destChunk.removeTileTicks(copy)

            tileTicksList = sourceChunk.getTileTicksInBox(destChunkBoxInSourceLevel)
            tt += len(tileTicksList)
            for tileTick in tileTicksList:
                eTag = deepcopy(tileTick)
                eTag['x'].value = tileTick['x'].value + copyOffset[0]
                eTag['y'].value = tileTick['y'].value + copyOffset[1]
                eTag['z'].value = tileTick['z'].value + copyOffset[2]
                destLevel.addTileTick(eTag)

            if biomes and hasattr(destChunk, 'Biomes') and hasattr(sourceChunk, 'Biomes'):
                destChunk.Biomes[destSlices[:2]] = sourceChunk.Biomes[sourceSlices[:2]]

        destChunk.chunkChanged()

    log.info("Duration: {0}".format(datetime.now() - startTime))
    log.info("Copied {0} entities and {1} tile entities and {2} tile ticks".format(e, t, tt))
 copy blocks between two infinite levels by looping through the
    destination's chunks. make a sub-box of the source level for each chunk
    and copy block and entities in the sub box to the dest chunk.
pymclevel/block_copy.py