PostFX - random numbers?

[peaman]

Hello

Anybody knows how to generate random numbers in glsl? I'm trying to write a blur effect with jitter. I know there are functions like noise1, noise2 etc. but somehow they seem not to do anything but return zero. Maybe I'm doing something wrong?

best regards

[Laurent]

I've read somewhere that noise functions where not implemented for some version of GLSL.

Why don't you just pass these numbers as variables from your C++ code ?

[peaman]

Hi

I don't pass the numbers because I need different ones for each pixel that is processed.
I'm thinking now about using a texture that contains the noise. That might be a workaround.

[deps]

I'm haven't used GLSL at all, ever, but you can still create functions in it? If so, why don't you make your own random function?

It won't be truly random, but there doesn't exist anything remotely like a truly random function on home computers. Yet it might be good enough to do what you want. You can pass values to it from C++ to use as a random seed. I'm sure you would find info about this rather quickly using google.

[peaman]

I'm haven't used GLSL at all, ever, but you can still create functions in it? If so, why don't you make your own random function?

It won't be truly random, but there doesn't exist anything remotely like a truly random function on home computers. Yet it might be good enough to do what you want. You can pass values to it from C++ to use as a random seed. I'm sure you would find info about this rather quickly using google.

thanks for the tip, but glsl has no static variables. Another problem is that there are no bitwise operations.

[deps]

Make it simpler?
Psuedo code:

Code: [Select]


int table[] = { 0,9,1,8,2,7,3,6,4,5 }
int random()
{
  int v = table[i];
  i++;
  if( i > 9 ) i = 0;
  return v;
}

Make the table bigger, is a nice suggestion.

But then again, a texture might be a better solution.

[workmad3]

texture is a better idea as textures are arrays for glsl

so a noise texture is the same as that idea, but with a large, auto-generated array