You'll still get a 1-in-3 chance of getting a tree just by using rand().

There are obviously better random number generators around which you
could use, ones which will give a better "randomness". You could look on
here:-

http://random.mat.sbg.ac.at/

Also, depending on processor speed, you will be executing several
hundred instructions in a millisecond.

--------------
Allan

-----Original Message-----
From: beginnersroguelikedevelopment@yahoogroups.com
[mailto:beginnersroguelikedevelopment@yahoogroups.com] On Behalf Of
gamer_2k4
Sent: 04 October 2005 03:13
To: beginnersroguelikedevelopment@yahoogroups.com
Subject: [Beginners Roguelike Development] Re: need help with a RNG


I use the random number generator for map creation, so if I want a 1
in 3 chance that a tree will be generated on a tile (instead of just
grass) and I have a 40 x 160 map, that's 6400 calculations in less
than a second. Even getting the milliseconds past midnight isn't
fast enough for that.

--- In beginnersroguelikedevelopment@yahoogroups.com, "allan175uk"
<allan@s...> wrote:
> I think you'd be better off just call srand() occasionally (or just
> once when your code starts).
>
> I tend to just call "srand(time(NULL))" near my program entry point
> and leave it at that, it seems pretty random to me! ;-)
>
> The last line (the return) is all you need really for a ranged
> random number.
>
> Also, even though PCs are getting faster & faster, calling time()
> once and GetTickCount() twice for *every* random number seems a bit
> excessive, especially as GetTickCount() will probably be returning
> the same number since the calls are only a few instructions apart!
>
> -----------
> Allan





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