Math::Random(float, float) ?

[aiaf]

Have a look at the output of this program run for a couple of times:

 

int main(int argc, const char *argv[])
{
srand(time(NULL));

for (int i = 0; i < 5; i++) {
 printf("%d ", rand() % 360);
}

printf("\n");

for (int i = 0; i < 5; i++) {
 printf("%f ", Math::Random(0.0, 360.0));
}

 

 

159 153 117 103 57

293.300507 48.771721 326.085083 300.603088 45.715256

 

168 350 54 276 33

293.300507 48.771721 326.085083 300.603088 45.715256

 

181 136 214 26 243

293.300507 48.771721 326.085083 300.603088 45.715256

 

I dont understand what happens with Math::Random, it returns the same numbers.

Using rand%360 looks ok.

[Thirsty Panther]

Math::Random is a pseudo random number generator.

 

This will explain it better than me.

[aiaf]

Yes and i use the current time as a seed.Still it doesnt change the values.

 

Below is a pseudo random generator from c++, it doesnt behave as Math::Random i just tested:

 

std::random_device seed;
std::mt19937 gen(time(NULL));
std::uniform_int_distribution<int> dist(0, 360);
for (int i = 0; i < 5; i++)
{
printf("%d ", dist(gen));
}

[macklebee]

Usually, when a program starts, it initializes the generator with a fixed seed. That means that, every time you run your program, it generates the same sequence of pseudo-random numbers.

 

]LE's Math:Random() doesn't have a way to change the seed.

[aiaf]

It should have is confusing.

Thanks for help, seem ill use the c++ random facilities.

[macklebee]

I lied to you!

 

It looks like Josh has added that at some point but doesn't have it documented yet. I can see from a lua global variable dump there is this command:

 

Math:SeedRandom(float)

 

EDIT-- just tried it and it appears to work properly. I get different numbers each time i run the program.

[aiaf]

Works!

Should be added in api documentation:

http://www.leadwerks.com/werkspace/page/api-reference/_/math/

[Einlander]

Amazingly I get the same first number every time even if I use the time as the seed. :/

[AggrorJorn]

Amazingly I get the same first number every time even if I use the time as the seed. :/

Are you using system time or application time?