const unsigned int numTiles = interactionCount[0];
int pos = (numTiles > maxTiles ? startTileIndex+get_group_id(0)*numTileIndices/get_num_groups(0) : get_group_id(0)*numTiles/get_num_groups(0));
int end = (numTiles > maxTiles ? startTileIndex+(get_group_id(0)+1)*numTileIndices/get_num_groups(0) : (get_group_id(0)+1)*numTiles/get_num_groups(0));