1. The Sky Texture
2. Adding a 3D Skybox

We have briefly covered the sky texture previously in the basic texturing tutorial, but we're going to go into depth on the subject now we're more advanced mappers.

Which Sky to Use?

Many mappers think that it's an arbitrary choice to select a sky texture. But it's not a matter of picking something that's pleasing to the eye. By the time you're ready to texture the sky, you should have the basic layout of the map and major architecture completed. This way, you can intelligently select a texture and time of the day that will best show off your architecture.

For example, Half-Life 2 Ravenholm in broad daylight probably woudln't have nearly the effect it has at night. The Highway 17 level along the coast would not be suitable at night. Imagine driving the airboat in pitch darkness. It wouldn't be very fun.

In addition, Counter-Strike: Source is a multiplayer game. A lot of mappers make their maps with a night sky texture, so most of the map is cloaked in darkness. It may be fun hiding in the shadows, but it can get tedious trying to tell friends from foes when a firefight breaks out in a dark outside area.

Generally speaking, night-time maps are not appropriate for Counter-Strike gameplay. There are exceptions, of course. If we tweak the ambiant light setting, we can make an excellent map set at night time. But this would take skill and considerable planning.

Another matter is the pitch of light_environment. Frequently, beginner mappers set this angle to -90, so the sunlight shines straight down. Lighting in high-noon doesn't provide very interesting shadows. If you pay close attention to de_dust or de_dust2, even though it's set in the afternoon, the pitch of the sunlight isn't exactly perpendicular to the ground. It's slightly off, just enough to create all sorts of beautiful contrasting shadows. We should learn from these official maps when we make our own.