func_areaportal

Well I know this is everywhere and in tut's and posts and stuff like that... But i still don't get it, does the engine render the props when the func_areaportal brush is VISIBLE to you or is it when the door it's inside, opens?

(Does it HAVE to be inside a door? I'm planning on using it in a vent, and doors aren't very common in vents :rolleyes: )

PLEASE, again, no linking to tut's that explain the same old cr*p, unless it's very clear that it answers my question! And answer me in a very n00b-friendly way

take a brush, made from the areaportal texture, and make it into a func_areaportal entity. this is non solid and invisible in-game. it works something like this.

when you are looking through a func_areaportal, the engine will do real time calculations of the faces that can be seen, and render only them. this causes an extra load on your system, and how much that is will depend on the scene being rendered. (the portal is open)

when the func_areaportal is not in your line of sight, then everything behind it gets dropped from all 'what can we see' calculations. (the portal is closed)

if you have an areaportal inside a door, then because the door isn't a vis blocker even when it's closed, the portal would normally still be considered viewable and would remain open. however, the areaportal properties allow you to name a door, and when the door is in an open or closed state, then the areaportal is forced to follow.

[post edited after i realised i'd been talking bollocks again]

a very important point to remember when using areaportals of any description, is that the area you seal with it must be 'leak-free' from any other sealed area. for example, if you made a corridor that went around in a big circle, and only used one func_areaportal(or door with a areaportal textured brush tied inside), then you'd get an error. this is because the ant that does the calculations for the engine gets disoriented, and doesn't understand how the same door is at both ends of the same corridor. this is when it starts running around making messy marks on your compile log.

when you use two or more areaportals, then the ant can go about its business, and take notes that portal1 is between the back of doors 1 and 2, and portal2 is in front of them etc.

and please dont leave cracks or gaps that the little guy will crawl through, he's got a hard enough time as it is. :wink:

---

i eat paint

So, i have to put a func_areaportal brush with areaportal texture up in the vent, and a non-solid brush with areaportal texture in the door?

Hope i get it right :eek:

hmm, not quite. it appears that what i said about the door is bollocks, so i've edited my post so as not to lead anyone else astray. it might even make a little sense now. :smile:

---

i eat paint

Oh now i get it, both types is the same, only the difference that you have to link the second to a door?

aye, that's about it in a nutshell. the one linked to a door gets told to forget about everything behind it when the door is closed.

---

i eat paint