if (currentTransform == null) {
currentTransform = transform;
}
ExtentBlockCopy blockCopy = new ExtentBlockCopy(source, from, destination, to, currentTransform);
RegionMaskingFilter filter = new RegionMaskingFilter(sourceMask, blockCopy);
RegionFunction function = sourceFunction != null ? new CombinedRegionFunction(filter, sourceFunction) : filter;
RegionVisitor blockVisitor = new RegionVisitor(region, function);
ExtentEntityCopy entityCopy = new ExtentEntityCopy(from, destination, to, currentTransform);