This tutorial is a mostly advanced tutorial but a beginner can do it if they really wanted too.
Lets first start off by downloading the COD4 godray texture in TGA format.
Extract the image to your IMAGES folder in the MAIN directory of COD2/4/W@W/BO (this technique can be applied to any new COD that has mod tools)
Now open ASSIST MANAGER:
1. Go to the white box, scroll down to "MATERIAL"
2.Press "New Entry"
3. Type in "cod4_godray"
Now do these next steps carefully.
5. set materialType to UNLIT (i did a mistake in the picture, thus is why UNLIT looks weird...lol)
6. Change surface type to "NONE", do NOT keep it at "error", cause if you dont, when you compile the image you will get *drumroll please*....an error, surprising right?
Keep "sort" the way it is, now change "usage" to SKY.
7.Put the "locale" as "Kiev"
8. Change "blendfuc" to "ADD"
9.Change "CULLFACE" to "NONE", this prevents the texture from "disappearing" when you go "behind" it, the texture will now appear at all angles now instead of only from the "Front"
(DON'T LISTEN TO THE Z-FEATHERING STUFF!) Unlit has no Z-feathering.
11. Find the image, I had my image in a custom named folder, you should have yours in the IMAGES folder.
READ CAREFULLY BELOW!!!
12. Go to advanced options at the bottom, change platform to PC/XENON, DONT FORGET THE NEXT STEP!
13. Go to ALPHA and change it to "ENABLE", now to go FILE, and save, make a gdt file.
Now after thats done, convert the image, and you are done! Now go to Radiant > TEXTURES (At the top of the toolbar) >USAGE >SKY It should be at the very top, sometimes it can be at the bottom also or in between.
IF NOT! Make a "caulk block" in the middle of the blank map, deselect everything, now to go TEXTUREs> FIND/REPLACE. put in "FIND": "caulk"
Put in "REPLACE": "cod4_godray" (the name of the material)
Fire textures are bit harder to do, dont use these settings for fire textures, it wont work...