Quote from NocturnalGhost on November 17, 2007, 11:06 am

Nice to see that you are taking the time to make a tutorial on this.

However, the way you describe making the "light tubes" is incorrect, and as you have noted in the wiki, bad mapping practice.

The tubes you describe are different dimensions to the valve ones, which isn't so bad, but also only contain 8 sides in total, which detracts considerably from the detail. Also, you should never carve something like this.

I have written a small guide detailing the way I make these. It is somewhat similar to how Valve appear to have made theirs, but not identical, mainly due to the fact they seem to have gone off the grid, which I personally think is bad, unless unavoidable.

Feel free to use any of the following in your tutorial, or modify it as you see fit for your purposes. I know it is a bit long, but I tried to be as detailed as possible. Sorry for the image-heavy nature of this post.

Observation Room Light Tubes

Make a square hole in the ceiling that measures 96 x 96. Make it 40 depth from the ceiling upwards, and add nodraw to the walls and new ceiling.

Using the arch tool, make a brush that is 80w x 80l x 48h
In the dialog, set:
Wall width : 16
Number of sides : 6
Arc : 90

The result will look like this.
[img]http://img80.imageshack.us/img80/1082/93661273iw0.jpg[/img]

Enter vertex manipulation mode, and align each part of the brush with the grid, as shown here, so the only "curve" is the inside part of the brush. This will make life easier for the compile process later.
[img]http://img207.imageshack.us/img207/7056/52711715mg6.gif[/img]

Using the clipping tool, clip the sides off your brush, so you are left with the following shape.

Copy > paste this brush, flip the new brush horizontally, and align it with the original brush to create a semicircular shape.

Select both brushes, copy>paste, flip the new brush vertically, and align to create a circular shape.

Build a frame around the base of the completed brush. Make each piece 8 units high, and 16 wide.

Texture the inside of the cylinder with plastic_light002c, and the base with plastic_light002a. For the base, check "treat as one", and use the "fit" button, to easily texture here.

Now, you should make a trim for where the base of the light tube meets the ceiling, although this is down to preference and room size.
Build an 8 high, 8 wide, 128 length block, and use the vertex tool to turn it into a triangle as shown. Click "yes" to merge the vertices.

Now, use the vertex tool to angle the outside corners to 45 degrees, so that when you have one of these on each side, the corners will meet up.

Copy>paste and flip as before, until you have the trim on all 4 sides. Texture the visible sides with plastic_wall002a

Turn the entire thing into a func_detail, and move it into the hole you created earlier. (Now might be a good time to save it as a prefab, so you don't need to do this again)
[img]http://img441.imageshack.us/img441/7654/12kl2.jpg[/img]

Texture the ceiling in your hole with the white009 texture.
[img]http://img441.imageshack.us/img441/6763/13kb3.jpg[/img]

It is worth noting that the texture scale you choose here can have a big impact on your room's lighting. The default scale of 0.25 will give a nice, bright effect, whereas scale 1.0 will be much dimmer. This can alter the mood of a map considerably.

[img]http://img206.imageshack.us/img206/1628/obstest1dy3.th.jpg[/img]

Also of note, in the example map, Valve used a texture scale of 50, so virtually no light was given off, and they just faked the effect of light with a light and a light_spot. Why they did this is a mystery, but it was probably to give more control over the lighting in that scene.