Random / noise functions for GLSL

Question

As the GPU driver vendors don't usually bother to implement noiseX in GLSL, I'm looking for a "graphics randomization swiss army knife" utility function set, preferably optimised to use within GPU shaders. I prefer GLSL, but code any language will do for me, I'm ok with translating it on my own to GLSL.

Specifically, I'd expect:

a) Pseudo-random functions - N-dimensional, uniform distribution over [-1,1] or over [0,1], calculated from M-dimensional seed (ideally being any value, but I'm OK with having the seed restrained to, say, 0..1 for uniform result distribution). Something like:

float random  (T seed);
vec2  random2 (T seed);
vec3  random3 (T seed);
vec4  random4 (T seed);
// T being either float, vec2, vec3, vec4 - ideally.

b) Continous noise like Perlin Noise - again, N-dimensional, +- uniform distribution, with constrained set of values and, well, looking good (some options to configure the appearance like Perlin levels could be useful too). I'd expect signatures like:

float noise  (T coord, TT seed);
vec2  noise2 (T coord, TT seed);
// ...

I'm not very much into random number generation theory, so I'd most eagerly go for a pre-made solution, but I'd also appreciate answers like "here's a very good, efficient 1D rand(), and let me explain you how to make a good N-dimensional rand() on top of it..." .

Answer 1

Gustavson's implementation uses a 1D texture

No it doesn't, not since 2005. It's just that people insist on downloading the old version. The version that is on the link you supplied uses only 8-bit 2D textures.

The new version by Ian McEwan of Ashima and myself does not use a texture, but runs at around half the speed on typical desktop platforms with lots of texture bandwidth. On mobile platforms, the textureless version might be faster because texturing is often a significant bottleneck.

Our actively maintained source repository is:

https://github.com/ashima/webgl-noise

A collection of both the textureless and texture-using versions of noise is here (using only 2D textures):

http://www.itn.liu.se/~stegu/simplexnoise/GLSL-noise-vs-noise.zip

If you have any specific questions, feel free to e-mail me directly (my email address can be found in the classicnoise*.glsl sources.)

Answer 2

hash: Nowadays webGL2.0 is there so integers are available in (w)GLSL. -> for quality portable hash (at similar cost than ugly float hashes) we can now use "serious" hashing techniques. IQ implemented some in https://www.shadertoy.com/view/XlXcW4 (and more)

E.g.:

  const uint k = 1103515245U;  // GLIB C
//const uint k = 134775813U;   // Delphi and Turbo Pascal
//const uint k = 20170906U;    // Today's date (use three days ago's dateif you want a prime)
//const uint k = 1664525U;     // Numerical Recipes

vec3 hash( uvec3 x )
{
    x = ((x>>8U)^x.yzx)*k;
    x = ((x>>8U)^x.yzx)*k;
    x = ((x>>8U)^x.yzx)*k;

    return vec3(x)*(1.0/float(0xffffffffU));
}

Answer 3

It occurs to me that you could use a simple integer hash function and insert the result into a float's mantissa. IIRC the GLSL spec guarantees 32-bit unsigned integers and IEEE binary32 float representation so it should be perfectly portable.

I gave this a try just now. The results are very good: it looks exactly like static with every input I tried, no visible patterns at all. In contrast the popular sin/fract snippet has fairly pronounced diagonal lines on my GPU given the same inputs.

One disadvantage is that it requires GLSL v3.30. And although it seems fast enough, I haven't empirically quantified its performance. AMD's Shader Analyzer claims 13.33 pixels per clock for the vec2 version on a HD5870. Contrast with 16 pixels per clock for the sin/fract snippet. So it is certainly a little slower.

Here's my implementation. I left it in various permutations of the idea to make it easier to derive your own functions from.

/*
    static.frag
    by Spatial
    05 July 2013
*/

#version 330 core

uniform float time;
out vec4 fragment;



// A single iteration of Bob Jenkins' One-At-A-Time hashing algorithm.
uint hash( uint x ) {
    x += ( x << 10u );
    x ^= ( x >>  6u );
    x += ( x <<  3u );
    x ^= ( x >> 11u );
    x += ( x << 15u );
    return x;
}



// Compound versions of the hashing algorithm I whipped together.
uint hash( uvec2 v ) { return hash( v.x ^ hash(v.y)                         ); }
uint hash( uvec3 v ) { return hash( v.x ^ hash(v.y) ^ hash(v.z)             ); }
uint hash( uvec4 v ) { return hash( v.x ^ hash(v.y) ^ hash(v.z) ^ hash(v.w) ); }



// Construct a float with half-open range [0:1] using low 23 bits.
// All zeroes yields 0.0, all ones yields the next smallest representable value below 1.0.
float floatConstruct( uint m ) {
    const uint ieeeMantissa = 0x007FFFFFu; // binary32 mantissa bitmask
    const uint ieeeOne      = 0x3F800000u; // 1.0 in IEEE binary32

    m &= ieeeMantissa;                     // Keep only mantissa bits (fractional part)
    m |= ieeeOne;                          // Add fractional part to 1.0

    float  f = uintBitsToFloat( m );       // Range [1:2]
    return f - 1.0;                        // Range [0:1]
}



// Pseudo-random value in half-open range [0:1].
float random( float x ) { return floatConstruct(hash(floatBitsToUint(x))); }
float random( vec2  v ) { return floatConstruct(hash(floatBitsToUint(v))); }
float random( vec3  v ) { return floatConstruct(hash(floatBitsToUint(v))); }
float random( vec4  v ) { return floatConstruct(hash(floatBitsToUint(v))); }





void main()
{
    vec3  inputs = vec3( gl_FragCoord.xy, time ); // Spatial and temporal inputs
    float rand   = random( inputs );              // Random per-pixel value
    vec3  luma   = vec3( rand );                  // Expand to RGB

    fragment = vec4( luma, 1.0 );
}

---

Screenshot:

I inspected the screenshot in an image editing program. There are 256 colours and the average value is 127, meaning the distribution is uniform and covers the expected range.

Answer 4

Just found this version of 3d noise for GPU, alledgedly it is the fastest one available:

#ifndef __noise_hlsl_
#define __noise_hlsl_

// hash based 3d value noise
// function taken from https://www.shadertoy.com/view/XslGRr
// Created by inigo quilez - iq/2013
// License Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

// ported from GLSL to HLSL

float hash( float n )
{
    return frac(sin(n)*43758.5453);
}

float noise( float3 x )
{
    // The noise function returns a value in the range -1.0f -> 1.0f

    float3 p = floor(x);
    float3 f = frac(x);

    f       = f*f*(3.0-2.0*f);
    float n = p.x + p.y*57.0 + 113.0*p.z;

    return lerp(lerp(lerp( hash(n+0.0), hash(n+1.0),f.x),
                   lerp( hash(n+57.0), hash(n+58.0),f.x),f.y),
               lerp(lerp( hash(n+113.0), hash(n+114.0),f.x),
                   lerp( hash(n+170.0), hash(n+171.0),f.x),f.y),f.z);
}

#endif

Answer 5

A straight, jagged version of 1d Perlin, essentially a random lfo zigzag.

half  rn(float xx){         
    half x0=floor(xx);
    half x1=x0+1;
    half v0 = frac(sin (x0*.014686)*31718.927+x0);
    half v1 = frac(sin (x1*.014686)*31718.927+x1);          

    return (v0*(1-frac(xx))+v1*(frac(xx)))*2-1*sin(xx);
}

I also have found 1-2-3-4d perlin noise on shadertoy owner inigo quilez perlin tutorial website, and voronoi and so forth, he has full fast implementations and codes for them.

Answer 6

There is also a nice implementation described here by McEwan and @StefanGustavson that looks like Perlin noise, but "does not require any setup, i.e. not textures nor uniform arrays. Just add it to your shader source code and call it wherever you want".

That's very handy, especially given that Gustavson's earlier implementation, which @dep linked to, uses a 1D texture, which is not supported in GLSL ES (the shader language of WebGL).