My goal is generate 2D or 3D geometry without having to store it on disk, so my goal is to have any sort of function than generate the same values according to a small seed. I don't mean to seek random values, but if the same "random" garbage data is returned when given the same seed, that's something I'm looking for.
If I give srand() the same integer, I get the same sequence out of rand(). Is that an intended feature? If not, are there known standard functions designed to do the same thing?
Although I tried this on ideone and on my computer and I get different results, I can understand that those function's implementations are not described, so that explains it.
If I give srand() the same integer, I get the same sequence out of rand(). Is that an intended feature?
Yes, see 7.20.2.2:
7.20.2.2 The srand function
[...] Description
The
srandfunction uses the argument as a seed for a new sequence of pseudo-random numbers to be returned by subsequent calls torand. Ifsrandis then called with the same seed value, the sequence of pseudo-random numbers shall be repeated.
However, that's only true for the same implementation of srand/rand. Another implementation might not use the same algorithm, and therefor won't produce the same sequence.
If not, are there known standard functions designed to do the same thing ?
Well, the functions are standard, but only in their behaviors, not the actual values (see implementation remark above). You're better off by using a specific generator from the C++11 predefined random number generators, since they're standardized.