Mission editor in arma3 is now called “eden”, it is 3D editor unlike the previous one ever since OFP beginning.
This page explains many mission editor features and how to do something with it, but this is not total beginner tutorial. If you are first time user then go through the eden editor tutorial (top right corner you see red “!” character on the icon) as it explains pretty nicely all the basics of the editor.
Trigger attributes “C” field is the height of the trigger. If you use value -1 it means its endless, goes as high/low as you can see.
Trigger condition you can use TriggerActivated command to check if another trigger has been activated.
Systems → Combat Patrol → Combat Patrol Init. This is all you need to start combat patrol mission on the current terrain using your squad.
Systems → Strategic → Open Strategic Map → Strategic Map → Mission. Then synchronize open strategic map to your player character.
This is the single selectable mission setup, you can add many more missions.
Play → Play In Multiplayer (MP) allows you to start mission in MP environment with hosted server.
This option works the same for Missions and MPMissions directories, there is no difference between these two directories, use them as you wish to organize your missions.
Importing 2D editor mission.sqm format is easy, just open such mission and eden asks you confirmation to convert the sqm file and to create backup file called mission.sqm.OldBackup in the same directory.
This old 2D editor mission.sqm must be up to date and valid with currently loaded addon classes because if it is not, eden editor just simply deletes the missing classes! Note: you can restore them from the mission.sqm.OldBackup file. Make sure you can load the mission in 2D editor without ANY errors before opening / importing it with eden editor.
How to move a group inside a vehicle, select the group and ALT-LMB drag it over the vehicle, units are put in.
CTRL-SHIFT-V pastes your copied objects into their original location.
Note that some objects may get funky pitch/bank, for example CUP NAPA weapon box gets placed sideways. You can fix this by selecting the box, ALT-LMB dragging the object up and setting it down again snapping to ground, now its aligned properly.
Align to ground all “entities”.
Select chracter, vehicle or object, RMB → transform → snap to surface.
Note that triggers and gamelogics cannot be aligned to ground unfortunately… unless you select chracter/vehicle/object along with them (yep, makes no sense but thats how it is).
When I want to make sure all my entities are aligned to ground properly I'll make sure the mapview is all the way zoomed out/back then do CTRL-A (select all) and then on the entities tab RMB to chracter/vehicle/object → transform → snap to surface. Works nicely.