Note: if you've never used BSP before, I suggest that you review some of my General BSP tutorials to get a feel for using the editor. These tutorials for Quake-specific items will be geared to people who are already comfortable with BSP.

Hi again everybody! Glad you came back. In this lesson, I thought we would learn a couple of neat lighting tricks. If you've ever played E1M5 of Quake, you might have noticed the shadow of a Quake symbol on the ground but there is nothing visible to cast the shadow. This is called 'sourceless shadowing' and is a really cool trick we'll learn in this lesson. Also, we'll learn how to make a spotlight.

Before we get started, we'll need a room to play around with, so I have one available here. It's the same room we used in the last lesson, but I removed all the prefabs we made. Load this level into BSP and we'll get started.

Okay, for sourceless shadowing to work, you have to use the sky brush. One trick of Quake is that light shines through sky brushes as if they aren't there, but the player can't see through them. This is really useful. In the map you just loaded, select the ceiling brush and give it a sky texture.

Now, if we put a light above this 'ceiling', we could make our shadow, but since the Light entity would be outside the map, QBSP would generate a leak. In order to get around this, we need to make a 'false' ceiling, lower than the original ceiling, so copy your sky brush and move the copy down to 128 on the Z axis.

Once you've got your false ceiling positioned, let's make a shape to cast a shadow. As a bonus in this lesson, I'll show you a method for making a Quake symbol. The brush count is kind of high for this shape, so you won't want to use it in a very large room, but it looks fairly decent. We'll start by making a brush 128x128 in the Top View. Give this any texture you want as long as it's not a liquid texture or sky texture. We won't see this brush, so the texture we use doesn't matter. Switch to a side view and position the bottom of this brush at 140 on the Z axis and make the brush 8 units tall.

Now, click on the cylinder button (remember we used that in the last lesson?) and enter the following information - Sides: 12, Strips: 1, Inner Radius: 4, Outer Radius: 64. Click OK and you will see a cylinder appear in place of the brush you drew. (If you want to lower your brush count, you could make these N-sided brushes instead of cylinders - just thought you might want to know.) All the brushes which make up this cylinder are selected, so copy them and paste a new copy. Manuever this copy so that it lies in the same place as the original, then with the pasted copies still selected, click on the Scale button. Scale these brushes .85 in the X dimension and .85 in the Y dimension. Once you've done this, switch to the Top View (if you're not already there) and drag these brushes 16 units towards the top of the screen.

Click on the subtract button. It may take a few seconds to do this, since you're subtracting a lot of brushes here. When it's finished, click on the trashcan button to delete the subtracted brushes. If there are any stray brushes left over (where the center of your subtracted brushes were for instance) delete them also. You should see something like this:

That's the hard part of making the Quake symbol. For the rest, simply make a brush from (-136, -56) to (-120, -152). Make it 8 units tall and set the bottom of the brush on 140, just like the cylinder you drew earlier. Now clip this brush from (-128, -152) to (-136, -128) and from (-120, -128) to (-128, -152). Make another brush from (-140, -52) to (-116, -56), also 8 units tall in the same vertical position as the others. At this point, your screen should resemble this:

Okay, that should provide us with something that will cast a shadow. Now all we need to do is add a light source and we're done. Make a light and center it directly over the Quake symbol and drag it up until it sits against the upper ceiling. I gave my light a value of 500. That way it provides a nice contrasting shadow in Quake. One thing to note here: the higher up you put your light source, the smaller the shadow it casts will be, but it won't be quite as sharp around the edges. Now, compile your map and run it in Quake. You should see something like the following screenshot. I used the 'fly' cheat code so I could get a better viewing angle in this picture.

Pretty cool, huh? This technique could be useful for more than just decoration. For instance, you could hide a secret door in the floor and make the shadow of an 'X' where the door is. Kind of an 'X marks the spot' thing. Just an idea.

Okay, now that we can make shadows, let's learn how to make a spotlight. This is really pretty simple, and you can use these to provide interesting lighting effects. Again, like the shadows, they could be used to highlight a secret door, or just for decoration. So, what do you say we get started?

Returning to your map, let's start out by making our original light a little dimmer. That way we can see our spotlight easier. Select the light entity that is above your Quake symbol and switch over to the Entity window. In the central box, select the key/value pair that reads 'light' '500'. These values will appear in the two boxes at the bottom of the screen. Change the 500 to 400 and click the '+' button to make the change take effect.

Now we're ready to make our spotlight. Start out by making a light entity, centered at (-44, 100) in the Top view. In a side view, move it up so that it is about halfway between the floor and the false ceiling we made earlier. Give this entity a light value of 300. Now draw a new brush and make it into an 'info_null' entity. This will be the target of our spotlight. Drag this brush so that it sits against the northern wall (in the Top View) directly north of the Light entity we drew earlier. In the side view, drag this 'info_null' entity up so that it is on the same vertical level as the Light.

Okay, now to make the spotlight work, select the Light entity and then CTRL-CLICK on the 'info_null' entity. This connects them together by assigning a Target/Targetname pair to each one. That's all there is to it. Run your level in Quake and you should see a bright spot of light on the wall. Pretty neat! If you did yours like mine, it should look something like this:

Remember that these two entities are linked. Wherever you put the 'info_null' entity, the spotlight will shine on that location. See, I told you it was easy!

Before we wrap this lesson up, there's something else you need to know about lighting. When compiling your level Light may bomb out if you have too many light styles on a given brush face. Each type of light you make (flicker, flourescent, spotlight, etc) counts as a light style. I'm not sure what the limit is, but if you get an error message complaining about 'Too many light styles on a face' this is the cause. Go into your map and remove some of the light styles - in other words, change some of the flickering lights to normal lights - and the problem should go away. The real trick is finding out where the error actually is in your map, since you don't get a coordinate with the error message. As a general rule, it's wise not to use too many flickering lights anyway, since flickering lights slow down your map, especially in deathmatch.