if( mRasterizeTasks.end() == std::find( mRasterizeTasks.begin(), mRasterizeTasks.end(), task ) )
{
mRasterizeTasks.push_back( task );
if( mRasterizeTasks.end() == std::find( mRasterizeTasks.begin(), mRasterizeTasks.end(), task ) )
{
mRasterizeTasks.push_back( task );