Note: This editing technique does not cover colored lighting used in MotS.
Lighting... where should I start? How about at the basics? First, lighting is an essential part of a JK level. Without it you would wander aimlessly in the dark, and we all know what it's like trying to find your way to the refrigerator late at night. :) One thing people may not know about lights is that they are not part of a normal JK level. Light information is only stored in a .jed file. It is important to remember while editing that lighting is static. Players cannot cast shadows. That is one reason JK runs so well; lighting is precalculated. There are two kinds of lighting covered in this technique: 1) - Light from positions and 2) - Light from sectors. We'll start with light from positions.
Light from positions comes from light objects (just referred to as lights) and is your basic form of light. To add a light to a level, switch to light mode by pressing "L" or the Light button, place the cursor where you want to have the light, and press "Insert". You may want to switch to a side view to make sure it's at the right height. In the Light editor you will notice two important sections: Intensity and Range.
Intensity - Intensity changes the brightness of the light. The values for lights run from 0 to 1. Anything over 1 acts as 1,
fully lit. Because light intensity decreases with range, a light with a value of 1 can give off a light value less than 1. So, values above
one are supported. Also, values below zero are supported (negative light) to completely darken a room.
The Light editor.
Also, there is one, single flag for lights: Not blocked. As you can probably guess, when this flag is checked, the light is not blocked by walls or other objects.
Since lighting is only stored on vertices, it may be a good idea to add lights with small ranges near vertices to specifically light a corner. Also, JED light calculations may give strange results when a light is placed directly on a surface. To avoid this, just place the light really close to the surface but not on it.
The second kind of light is Light from sectors. This may sound a little confusing, but you'll understand in a minute. Under the Sector editor you will notice a section titled Extra Light. This setting is like the intensity setting mentioned above but has no range because the entire sector is lit with this setting. The Extra Light setting is usually used for special effects in COGs.
Sector editor with Extra Light Setting.
Now, let's calculate the lighting. There are two ways to calculate lighting: 1) - Normal, which adds lights to the .jed file and 2) - On visible layers, which will calculate lighting only on layers that are set to visible. To access these, select Tools menu; they should be the first two.
Well, that just about wraps up the basics of lighting in JK. Remember, this editing technique does not address colored lighting used in MotS.