Hi. I don't know if Source mods are able to modify the map-loading screen, but I think it would add a lot to the game. Urban Terror is a great example of map-loading eye candy. I've attached some screenshots. As the map loads a semi-transparent mask is removed from the map picture that corresponds to the % loaded. It looks very awesome. It would also allow mappers to add a screenshot picture and map name to the loading screen. EDIT: Sorry the pictures are so small. I wasn't able to screenshot the loading screen so those were the best I could find on google images. For best effect, download the free game and load up a map.
yeah really nice idea. I want to see about 20 possible screens from the map for each map load, so that each time the map loads you get a different screen.
I think he was refering to the map fade thing, I know the custom loading background is possible, Irongrip did the same thing.
Like Bodrick mentioned, the Dystopia mod does something very much like this. When loading a map, it will show a screenshot right above the loading bar. It doesn't do any of that "semi transparent mask" stuff though.
You could probably do an animated texture there, that may work out ok. Don't know how you would get it to depend on loading times though :p
about the semi-transparency thingy, HL2 does it when you load the game. It has an image thats relevant to your progress in the game and is somewhat blurred, and when it finishes loading its a clear image.
I'm sure the Source engine can handle it, knowing that there are source based games out there that have this, I'm not so sure that Valve allows this for mods though.. Best, easiest and fastest way to find out is by sending them an email asking if this is possible for modifications. http://developer.valvesoftware.com/wiki/Help_Desk
There is only a single material displayed in the bottom left corner (this is usually the grey, rounded "loading..." message. This can be modified, but AFAIK only one can be used, so you can't get different ones for different maps. This is the only change made to the loading screen whilst connecting to a server (i.e. loading a map). It's something I'd definitely like to see, so I would go for that valve support thing, but equally don't get your hopes too high.