Disco Light Effect
First of all make a room
Now we gonna greate an arch as shown here.
When we have that just turn your arch horizontaly
Now make it func_rotating by using the to-entity button (CTRL + T)
Now only thing we need to change is the name, call it rot1
When we have that choose point_spotlight from the object selection.
Then place it on your func_rotating
Make sure the spotlight are facing the correct direction.
(you'll see yellow stripes if you click on an spotlight in 2D view, the yellow stripe shows where the light is facing.)
Then select all your point_spotlights (by holding your CTRL key) and then right click in 2D view ->Properties
Then click on spotlight length and change 500 to 1000 and click on parent and type rot1
Now deselect all spotlights and select 2 spotlights, then go to properties again then click colour > pick colour and use your favourite colour.
In this tut I'll use blue for these 2 spotlights
Then select the other 2 spotlights and choose another colour
Now go to your properties of your func_rotating and go to flags,
check start on and x-axis (you can also check y-axis)
Ok we're almost finishted you only need to put a dim light in your map, select the light entity and place it above your func_rotating, go to brightness and make it black
Now your disco light should work.