How to get item positions on a transport-belt?

[uukgoblin]

I would like to know the precise positions of items held by a transport belt's lane.

I couldn't find any appropriate method in LuaTransportLine, except can_insert_at(), which is a very indirect way of finding where the items might be placed. It also doesn't say what items there are.

Using the LuaTransportLine's operator[] does tell me what items there are on the lane, but I can't figure out a way to get the LuaItemStacks' positions.

I also tried find_entities() on the nauvis LuaSurface, but that only seems to find the transport belt itself, not items lying on it.

Are items lying on the belt also LuaEntities? Can I find them somehow?

[eradicator]

Are items lying on the belt also LuaEntities?

No. Historically they once were, but belts have been heavily performance-optimized.
I don't think there's a way to get the pixel-perfect stack position. The index of a stack in a LuaTransportLine - as you already know - covers a range of positions on the belt.

[DaveMcW]

I also needed to find the items on a single transport-belt, and I found a workaround.

If you mark a transport-belt for deconstruction, this breaks its connections. Then get_transport_line() returns a LuaTransportLine containing exactly the items on that belt.

[eradicator]

I also needed to find the items on a single transport-belt, and I found a workaround.

If you mark a transport-belt for deconstruction, this breaks its connections. Then get_transport_line() returns a LuaTransportLine containing exactly the items on that belt.

LuaEntity.get_transport_line() always returns a transport line for just that one belt.