Thanks for your detailed answer!! That’s help a lot!
I also wonder how editor know which actors is considered selected when left mouse button is clicked?
Generally, in game logic we will project the location of cursor to world space (FVector Start, FVector End) and then use LineTraceByChannel to find which actors is under cursor when clicking. This solution require the collision of actors is enabled.
However, we can select collision-disabled actors in editor by left mouse button. How editor achieve? What happen between “clicking on level editor” and “actors is marked selected”?
Thanks your patient answer again!