Checking if a map cell is occupied by a building

[eduran]

Is there a smart way to do that? It's required to make a placeable custom unit. The best idea I've come up with is to use GetAllUnitsInRange. If no unit is found, great. Otherwise I'd need to check if the unit takes map space (think PZs, ore patches, air units, CRPL cores). And there are Titans and CNs (or CRPL cores with a custom size), which are not 3x3, so those need to be handled in some way. Seems like a lot of work that has to be done each game tick, while the building preview is following the player's mouse cursor.
Any ideas on how to best tackle the issue?

[planetfall]

This is rather irritating for me too... my suggestion would be a separate core that watches all units and stores a list of occupied coordinates and only updates when one moves, is built or is destroyed, but that's without having tried it and knowing if it's possible or efficient.

[Clean0nion]

This is rather irritating for me too... my suggestion would be a separate core that watches all units and stores a list of occupied coordinates and only updates when one moves, is built or is destroyed, but that's without having tried it and knowing if it's possible or efficient.

Three lists. X, Y, and UnitType.

[J]

Does GetUnitAt return the unit even if it's not the center cell of that unit?

[eduran]

Does GetUnitAt return the unit even if it's not the center cell of that unit?

Sadly, no. It also runs into trouble when multiple units are in the same spot. It could find the ore patch underneath a mine/air unit above a building/PZ under a building and tell you it's save to build there.

a separate core that watches all units and stores a list of occupied coordinates and only updates when one moves, is built or is destroyed

But how do you know if a unit moved or was destroyed? Call GetAllUnitsInRange and compare the output to your list, probably. Unless there is another way, I think keeping the list up-to-date is more work than simply calling GetAllUnitsRange without storing the output.

[knucracker]

The game has an internal occupiedMap that it keeps. It is an array that stores a count of the number of things occupying a cell. I'm looking to stop adding additional Apis to crpl but this will be trivial to expose and since I've not released the new build yet because I'm working on a couple other things...

[Clean0nion]

The game has an internal occupiedMap that it keeps. It is an array that stores a count of the number of things occupying a cell. I'm looking to stop adding additional Apis to crpl but this will be trivial to expose and since I've not released the new build yet because I'm working on a couple other things...

So is that available as a list, or just hidden at the current build?

[knucracker]

It isn't available in the current build.  I'll add an api to return the count of a given map location in the upcoming build.

[kwinse]

GetCellOccupiedCount is working great, thanks Virgil!