[Beginner] Help with random-colored Circles

[Cadisol87]

Hey Guys, I'm here again with my problem:
I got some circles bouncing around in a window. But I want that the circles change their color when they collide with a wall.

This may seems very simple, but trust me, it's harder than It looks.
The problem I have, is that the colors are always similar.

Let me explain the problem more in detail:

I got a random function, which generates a random number between 1 and 255. I uses the elapsed time of a clock in microseconds as seed. The function works fine.

But now theres a problem: When I try to set the FillColor of the Circle like this:

Circle.setFillColor(sf::Color(Random(clockSeed) , Random(clockSeed) , Random(clockSeed));
 

The Circle will always get a grey color, because Red, Green and Blue have the same value.

Then I tried something like this:

Circle.setFillColor(sf::Color(Random(clockSeed * 2) , Random(clockSeed * clockSeed) , Random(clockSeed));
 

And a LOT of other methods to give each color a different value.
But that works neither, now the Circles have similar colors, because the 'proportions' of the color's values are always the same.

I have some Ideas for nasty solutions, but does anyone have an smart solution?

(Probably the solution is obvious and my brain is just stuck...)

Thanks In advance for your answers!

[G.]

Show your Random function.
Seed your random generator only once, you'll get different random numbers each time you call your function.

[Jesper Juhl]

If you seed a PRNG multiple times with the same number (which it looks like you are doing) you'll get the same sequence of numbers each time. So it's no surprise that you get grey colors like 100,100,100 or 42,42,42 with what you are doing.

[Laurent]

Moreover, using a random value for each RGB component will always give more or less grey colors. To have a better distribution within the color space, you should use HSV components to define your colors.

[Njifra]

This might help you:

srand(time(NULL));
Circle.setFillColor(sf::Color(rand() % 255, rand() % 255, rand() % 255));
 

[Cadisol87]

This might help you:

srand(time(NULL));
Circle.setFillColor(sf::Color(rand() % 255, rand() % 255, rand() % 255));
 

Haha, no sorry First of all, this method would only generate random numbers from 0 to 254, not 255.
Moreover, every number generated would be the same for every color, using this method. And if you use the time as seed, the seed will only change every second, so if two different balls collide with the wall within a second, they will have the same color.

If you seed a PRNG multiple times with the same number (which it looks like you are doing) you'll get the same sequence of numbers each time. So it's no surprise that you get grey colors like 100,100,100 or 42,42,42 with what you are doing.

I know, but I said that in my first post too :

But now theres a problem: When I try to set the FillColor of the Circle like this:

Circle.setFillColor(sf::Color(Random(clockSeed) , Random(clockSeed) , Random(clockSeed));
 

The Circle will always get a grey color, because Red, Green and Blue have the same value.

... you'll get different random numbers each time you call your function.

But that isn't the problem! I get different numbers each time I call the function...

Moreover, using a random value for each RGB component will always give more or less grey colors. To have a better distribution within the color space, you should use HSV components to define your colors.

Hmmm, Okay I will try to implement that, but I think I have to write a function to convert HSV to RGB?

[Laurent]

And if you use the time as seed, the seed will only change every second, so if two different balls collide with the wall within a second, they will have the same color.

The seed is just the initial value. You still get a new random value everytime you call std::rand().

[BaneTrapper]

srand(time(NULL));
Circle.setFillColor(sf::Color(rand() % 255, rand() % 255, rand() % 255));
 

Haha, no sorry First of all, this method would only generate random numbers from 0 to 254, not 255.
Moreover, every number generated would be the same for every color, using this method. And if you use the time as seed, the seed will only change every second, so if two different balls collide with the wall within a second, they will have the same color.

Every call to rand() will give you different result.
Seed is the starting point of the algorithm that is used to produce the number.

If you want to be fancy you can just create your own pallet of colors and random from those, that will provide you with nice choice of colors and to the user "random" color each time.

From "Laurent"s post the "HSV" , googling "HSV components to define your colors." gave a great result/answet to the post.

[Cadisol87]

Oh, Okay... Thanks for pointing that out, I didn't know that... I rarely used random numbers in C++, thanks for your help