A regular func_glass window will break from 1 hit,
something that's not looking good in terms of realism,
especially when the window sizes over 2 meters...

The SP mode has a realistic feature where glass
breaks into a huge amount of smaller bits and pieces.
For my knowledge, this option is not available in mp.

If you still want real glass into your maps, do what I do:

Split the glass.
Hit "x" for the cutting tool,
select 2 points across the brush and press shift + enter.
Reselect only 1 of the new brushes, split it again.



Repeat as many times as you see necessary.
A good cutting pattern in my opinion is a "spiderweb":

Start all lines at the outer edges and end them near the center of the window. Then split each brush seperate again
at the tip of it, near the center.



Good so far, but note it's treated as one group
if you made it "func_glass" before splitting it.



Leaving the window like this would be pretty stupid, since when damaged, ALL the parts break at once, in spite of all the splitting work...

(step A) So now comes the slow part: make every single brush alone "func_glass".



There you go. Now it will break more realisticly into multiple bits when hit in the game. Oh, and remember to select all those brushes and make them detail (ctrl + m) !

NOTE: Do not make this selection "func_group" after this point any more, 'cos this will overwrite the "func_glass" setting and you would have to repeat 'step A' again !

So if you want to make glass like this, first make sure you have a window slot(s) set up for it that you aren't going to resize anymore. Then make a brush that fits,
split it. If you got more window slots the same size, select the glassparts one by one, copy it (space), and move it into place.

Something I'm not sure about,
and I'd like to get an answer to is:

How much does a window like this eat up memory/fps ?
My hotel has already 6 floors, each with at least 20 windows,
that's 120 func_glass brushes. Is it okay if I have them all split, say into 8 bits, making the total count of func_glass brushes sum up to ... uhm...
(gets calculator )
... ~ 1000 ???

Came to think about the inner bits.
If the outer bits are smashed, the inner ones won't have any contact and will look pretty odd just "hanging in air".
This is a minor downside in the looks on
making a window like this.

And I think the inner bits are more likely to get smashed anyways at first. And if not, then a few seconds after for sure.
AAAAAND... even if they stay untouched that far, the next player looking at them will for sure spend only 1 sec wondering to himself :"Man, those little pieces of glass hanging in the air like that really get on my nerves", and smash them.



Or, just leave the inner bits out.
Make a "simple" split into it. One brush at the time, from one end to the other. This way all brushes touch the wall in some way and there won't be any "magic bits" hanging around later.

theres another way to do it where the glass doesnt float but these extra bits of window will create a LOT of tris, so i recommend you dont make them! besides, if you continue the way your going you will quickly reach the limit of glass in the map, its 512 or 1024 -- somewhere around there. just be happy with normal one pane windows, 6 floors is probably pushing it as it is.

Got the info on other limitations like max brushes, etc ?
All the map info figures ?

Hotel is 60%done, has 3500 total brush counted...

You do realise that a high amount of func brushes causes lower fps?

elemenz i see you are ignoring the sticky post too! all the limits and much more are listed in the FAQ, everyone is supposed to read it before posting - go read it now

the limit is 2048 for all ents, i dont know if windows have their own limit, probably not. the brush limit is 8192.

the recommended range for r_speeds: 8000 to 10,000 on average. if you go too far over that then the map wont be playable on older computers. you should check your r_speed to make sure its not too high.

speaking more on the FPS, it doesnt even matter the size of the brushes you make [to a certain extent] because each tris counts the same. and its often the small details you try to add that sends the r_speed through the roof. ive tried to make my map look fairly realistic and in doing so my r_speed is up to 15,000 in some areas... not good for an older computer at all -- it goes to 5 FPS there on an old pc of mine. i might make things look uglier just so i can play it on my lan.

Detail should be added from models. Not brushes.

Well thats from my experience from mapping.