But unlike lego bricks where you are limited to the number, shape and colour of the bricks in your lego set, in Radiant you can create as many bricks, with whatever size, shape and colours as you want.

To create a brush click and drag in the 2D window.  A newly created brush is automatically selected, so it shows in a dashed red outline.  To deselect your selection, press ESC.  To select a brush, press shift+click.  You can keep adding to a selection by selecting additional brushes.  You can delete a selection by pressing Backspace.

You can see your brush in the 3D window - move the 3D view around until you can see your brush nice and centrally (right click in the 3D window and use the mouse/arrow keys).  It will be a blue/black check (when not selected) with "Shader not found" written on it.  We'll sort out some proper textures later.

The size of the brush you create is up to you, but its edges are always aligned to the grid.  It is very important to use the right grid scale when creating brushes.  You can specify the grid size by using the keys 1 to 9.  Use 8-9 for large scale creation; use 5-7 for medium; use 3-4 for small.  Use 1-2 only when you really need to get down to the tiny level.  By default Radiant starts up with a grid size of 4, which is quite small.  If you make large walls etc using a small grid scale, you will find it very hard to get the major structures to line up as you put walls together. So use the largest grid scale you can for your large scale building blocks.  It will be painful later on if you don't! It doesn't matter for this first build-a-room tutorial, but it certainly will when your development projects are bigger. Quick mention of scale: the grid unit measurement equates more or less to 1 inch in the real world.  So I assume a player is 72 units high and make ordinary doors 84 units high to give about a foot clearance.

To move a brush in the 2D window, put the cursor within the brush outline and click/drag.  You can move in any axis by first changing the 2D view (cycle through the view by ctrl+tab).  Generally if you have used ctrl+tab, make sure you end up in the overhead view (the blue Z will be large and in a box).

To move a brush in the 3D window, put the cursor within the brush and click/drag.  The axes you can move it in will depend on your viewpoint and in which direction you are looking.

Have a go at moving the brush in each of the 3 dimensions.  When you're done, leave the brush roughly around the 0,0,0 co-ordinate, ie where the XYZ axes are shown on the grid.  

To resize a brush in the 2D window, put the cursor just outside the edge of the brush and click/drag.  When you drag you resize in the direction you drag in - drag away to make larger, drag inward to make smaller.

Have a go at resizing the brush in each of the 3 dimensions.  When you're done, leave the brush as shown in these pictures (a flat square).  On subsequent views of the map you may need to reverse a little in the 3D window in order to see the square.  This is because the camera will start at the origin (0,0,0) and will be looking at the inside.

Overhead view	Side view

A texture is the name given to the image applied to the face of a brush.

A brush typically has 6 faces, all of which will have a texture applied.  At the simplest level a texture on a face will be a JPG or TGA file of anything from a single colour up to an image of the Mona Lisa.  Some special textures are used for the faces that don't need to be drawn, for example where two faces are flush against each other, or a face faces away from any player and will never be seen (and so need not have a visible texture applied to it).

One special texture for this purpose is called Caulk.  Faces with caulk on them are not drawn, and so must never be somewhere that a player could look at it.  You've probably played a map where a caulked face is accidentally visible, and you get a weird hall of mirrors effect while you look at it.  So you must ensure all caulked faces cannot be seen.

In making a map you should be trying to achieve your design aims using the least number of brushes and the least number of visible faces as possible.  One way to achieve the latter is to create your brushes initially entirely from the caulk texture.  Then you "paint" the visible faces with the required texture, safe in the knowledge that all the other faces are caulked.

For example, say you created a brush to be used as floor in a room.  You decide to make the whole brush a wood texture and you slot the brush into place.  You forget to later caulk the bits you can no longer see, so you end up with 5 other faces that the engine must consider when deciding what to draw, when if they had all been caulk it would not present this overhead.  It may seem like small fry, but a map like 2tanks has 8,000 brushes, and so about 48,000 faces, which translates to around 96,000 triangles to be considered and possibly drawn.  As you want to try to keep the maximum number of triangles drawn to under perhaps 40,000 you need to ensure you use caulk wherever possible.

So let's start correctly with the flat square we've created.  We're going to make that the floor.  We caulk an entire brush by selecting the brush and clicking the Caulk button.

Textures are applied in the 3D window.  Point at the top face of the flat square and press ctrl+shift+click.  (To cancel the face selection, press ESC.  You can select multiple faces by pointing at more faces one at a time and ctrl+shift+click them into the selection.  You can also deselect a selected face in the same way.)

Now we need to tell Radiant what texture to apply.

At this stage it is unimportant that your \etmain folder contains extra PK3 files, like custom maps.  But as you get deeper into the mapping it becomes important that your \etmain folder doe not have them.  Radiant will show you the textures in those PK3s as available for you to choose.  And you will not realize that the town you have lovingly created uses 25 textures scattered across lots of other PK3s, and because they won't be in your PK3 when you proudly distribute your new map, everyone else will see the ugly yellow/black squares texture all over the place - oops :(

Click the "textures" menu item.  You can now choose to see the textures available under the various folder names.  It's a bit of trial and error here as you go looking for the texture you'd like.  For now choose Wood.  All the textures in the folder will now show in your textures window.  Don't worry about those that show as red/black squares.

Click on one you like; I am using wood_m05a_usata.

Ok, we've created a floor!

Next lesson