Complex geometry:part 1

Now I will show you how to use the clip tool and how to make doors, windows, etc.

First of all, load an example map. Make a wall and select it. Click on the clipping tool and drag your mouse in one of the 2d views. The mouse will make a white line which should intersect with your brush. It should look this

You may have noticed that the brush is divided into 2 red and white portions. Clyou ick on the clipping tool to interchange the red and white portions and click on it the 3rd time to make both the portions white. The white portion indicates the part which is going to remain after the cut while the red portion indicates the portion which is going to be deleted after the cut. For this example click the clip tool till both the portions turn white. Click on enter to confirm the cut.

Now you have 2 brushes. Select the bottom brush and clip it vertically. See the screenshot below if you get confused. Now clip the brush again and delete the middle portion forming a door(sort of).
Done?
Now select the brush on the left side(or the side which has the most space) and make 2 cuts both horizontally and select the middle brush and clip it 2 times vertically. Delete the brush in the middle. There, you have formed a window and a doorway. My example looks like this: