[2.0.59] Inserter Pickup position seems not correct

[hgschmie]

This is a miniloader. It is a composite entity that has multiple hidden inserters inside (up to eight, typically two).

In this picture, the light green box is the pickup position for an inserter, the red box is the dropoff position. The dark green boxes are potential inserter pickup positions, but as this entity has only two inserters, only 1 and 2 are active.

Screenshot 2025-07-09 at 21.45.36.png (785.12 KiB) Viewed 137 times

However (as one can see in this picture), the items "disappear" from the "7" and "8" position. Even though the inserters should only pick up on "1" and "2", they seem to grab further left than they should. They are configured with 'chases_belt_items = false'

This seems to be a bug. The inserters should only pick up from the configured positions (so items on the belt should roll all the way to the "1" and "2" position and then disappear, not before.

[boskid]

Thanks for the report however there are no bugs here.

Setting chases_belt_items to false affects only one part of inserter logic: inserter hand does not need to move to the position of the item to be picked up, instead the inserter hand just moves to the pickup position and once there it assumes it can instantly grab any item it wants. This flag does not imply that it is restricted to only grabbing item exactly at the pickup position nor that it would prioritize taking item closest to the pickup position.

When inserter selects item to be picked up, it always looks for the farthest item available on the line as this usually gives it the most amount of time to move towards it and pickup it when the item chasing is involved. This is hot code path and i do not want to be adding extra conditionals here that switch the inserter behavior into selecting item that is closest to the pickup target because that would not make item positions 7 and 8 to become invalid pickup positions: if there are no other items the inserter would still be allowed to take from positions 7 and 8 and as such this behavior would be purely cosmetic behavior change to make inserter take from the head of line first.