Alright wrote a quick Tutorial:
First off construct your door. Doesn't matter wether you make it out of one or multiple func_door
groups you'll just have to include a target_relay when you use more groups for more complex door structures.
Assign these parameters to it:
the target and targetname may vary since it's assigned randomly when you link the two entities via STRG+k
Now construct your button. Now instead of turning it into a func_button as you may have thought make it into a func_breakable
with these parameters:
Construct a brush infront of your fake button. keep it's dimensions somewhere in between 48x48x88 to 96x96x88, depending on wether you want people to have to be next to the button to activate it or just roughly in the range of the button (may be helpful to smoothen gameplay).
Now assign the trigger texture to the brush and turn it into a trigger_multiple
. Link this to the func_door and assign it following parameters:
Create a target_deactivate
and link the func_breakable button to it. Now link the target_deactivate to the trigger_multiple. Now as soon as the breakable is destroyed the trigger multiple won't work anymore and *tadaa* you've got your deactivated door.
here's a top-view scheme to make it clear:
aaaaaaaaaaaaand finnaly a radiant view:
actually pretty easy once you've found out. I've fiddled with masses of triggers and target entities for about two hours until I got it working.