The clipper tool is one the most useful tools in Radiant when it comes to brushwork. Think of it as your knife for cutting brushes. You can access the clipper tool by pressing x when you are in Radiant. Before you start, go to Edit>Preference>Setting>Clipper, and be sure that "clipper tool uses caulk" is checked:
Two Points Clipping
We will make a basic brush and try to cut the corner. First, do a basic brush, press x, go to the top view, and place your two clipping points with a left click like this:
You now see a plane cutting your brush in your 3D view and a line in
your 2D view, your brush will be cut along this.
But before doing so, you may notice that one side of the plane is blue
(the other is not). Everything behind this blue plane will be erased,
the rest of the brush will remain.
If the blue plane is not in the correct direction press ctrl+Enter" to reverse it.
Now press Enter to proceed:
You can repeat the operation to cut the three other corners, and you can do it in other 2D views as well.
Notice that when you use 2 point clipping you only need one plane to work, for example if you use the top view, moving clipping points along the Z axis will have no effect.
You may have heard that overlapping brushes is not a good idea. However sometimes you want to connect complex brushes together, which can be hard ... if you don't use the clipper.
First, go to the left view and make a slope by using the previous method:
Then make a second brush like this :
Our two brushes or now overlapping. To prevent that, we will just clip this second brush along the exact same line we did with the previous one:
Now our two brushes match perfectly and the faces you can't see are caulked.
You may also want to split your brush rather than deleting one part of it. To proceed press Shift+Enter intead of Enter.
It is very useful for texturing:
Three Points Clipping
Two points clipping can only cut along three directions. But you
sometimes want more advanced clipping than that, that's where you use
three point clipping. As three points define a plane in space, you will
be able to do anything you want with three points clipping.
First, use your clipper to make a brush that looks like this:
Then we want it to be 45 degrees from the wall to the slope as well,
and you can't do that with two points clipping.
Now it can be a bit confusing, but there is a simple method you can
always use: find three non aligned points which will be on your final
face of the clipped brush.
One way do this could be:
You are now a pro with the clipper tool!
Here you can get the map files for this tutorial: