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 menu Edit -> Preference -> Setting -> Clipper, and be sure that "clipper tool uses caulk" is checked:

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  1. Two Points Clipping

    1. Brush Modeling

      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:

      (Image screen2a) (Image screen2b)
      (Image screen2c) (Image screen2d)

      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:

      (Image screen3a) (Image screen3b)
      (Image screen3c) (Image screen3d)

      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.

    2. Brush connecting

      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:

      (Image screen4a) (Image screen4b)
      (Image screen4c) (Image screen4d)
      (Image screen5a) (Image screen5b)
      (Image screen5c) (Image screen5d)

      Then make a second brush like this :

      (Image screen6a) (Image screen6b)
      (Image screen6c) (Image screen6d)

      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:

      (Image screen7a) (Image screen7b)
      (Image screen7c) (Image screen7d)
      (Image screen8a) (Image screen8b)
      (Image screen8c) (Image screen8d)

      Now our two brushes match perfectly and the faces you can't see are caulked.

    3. Brush Splitting

      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:

      (Image screen9a) (Image screen9b)
      (Image screen9c) (Image screen9d)
      (Image screen10a) (Image screen10b)
      (Image screen10c) (Image screen10d)
  2. 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:

    (Image screen11a) (Image screen11b)
    (Image screen11c) (Image screen11d)

    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:

    (Image screen12a) (Image screen12b)
    (Image screen12c) (Image screen12d)
    (Image screen13a) (Image screen13b)
    (Image screen13c) (Image screen13d)

You are now a pro with the clipper tool!

Here you can get the map files for this tutorial:

Written by MidiMightyMoe