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/*
=======================================================
SIGGRAPH 2019 submission paper_0306
=======================================================
This code is for reviewing only.
!!! Do not distribute !!!
=======================================================
HowTo:
------
Copy-paste the code into https://shadertoy.com/new/
=> Please be careful not to save the shader in shadertoy
Click on the play button at the bottom left of the
code window.
Comment/uncomment lines at the bottom to try different
noises and profiles.
Thank you!
=======================================================
*/
# define M_PI 3.14159265358979323846
//phasor noise parameters
float _f = 25.0;
float _b = 8.0;
float _o = 1.0;
float _kr;
int _impPerKernel = 32;
int _seed = 1;
vec2 phasor(vec2 x, float f, float b, float o, float phi)
{
float a = exp(-M_PI * (b * b) * ((x.x * x.x) + (x.y * x.y)));
float s = sin (2.0* M_PI * f * (x.x*cos( o) + x.y * sin(o)) + phi);
float c = cos (2.0* M_PI * f * (x.x*cos( o) + x.y * sin(o)) + phi);
return vec2(a*c,a*s);
}
///////////////////////////////////////////////
//prng
///////////////////////////////////////////////
int N = 15487469;
int x_;
void seed(int s){x_ = s;}
int next() { x_ *= 3039177861; x_ = x_ % N;return x_; }
float uni_0_1() {return float(next()) / float(N);}
float uni(float min, float max){ return min + (uni_0_1() * (max - min));}
int poisson(float mean)
{
float g_ = exp(-mean);
int em = 0;
float t = uni_0_1();
while (t > g_) {
++em;
t *= uni_0_1();
}
return em;
}
int morton(int x, int y)
{
int z = 0;
for (int i = 0 ; i < 32* 4 ; i++) {
z |= ((x & (1 << i)) << i) | ((y & (1 << i)) << (i + 1));
}
return z;
}
void init_noise()
{
_kr = sqrt(-log(0.05) / M_PI) / _b;
}
vec2 cell(ivec2 ij, vec2 uv, float f, float b, float o)
{
int s= morton(ij.x,ij.y) + 333;
s = s==0? 1: s +_seed;
seed(s);
int impulse =0;
int nImpulse = _impPerKernel;
float cellsz = 2.0 * _kr;
vec2 noise = vec2(0.0);
while (impulse <= nImpulse){
vec2 impulse_centre = vec2(uni_0_1(),uni_0_1());
vec2 d = (uv - impulse_centre) *cellsz;
float rp = uni(0.0,2.0*M_PI);
noise += phasor(d, f, b ,o,rp );
impulse++;
}
return noise;
}
vec2 eval_noise(vec2 uv, float f, float b, float o)
{
float cellsz = 2.0 *_kr;
vec2 _ij = uv / cellsz;
ivec2 ij = ivec2(_ij);
vec2 fij = _ij - vec2(ij);
vec2 noise = vec2(0.0);
for (int j = -2; j <= 2; j++) {
for (int i = -2; i <= 2; i++) {
ivec2 nij = ivec2(i, j);
noise += cell(ij + nij , fij - vec2(nij),f,b,o );
}
}
return noise;
}
float PWM(float x, float r)
{
return mod(x,2.0*M_PI)> 2.0*M_PI *r ? 1.0 : 0.0;
}
float square(float x)
{
return PWM(x,0.5);
}
float sawTooth(float x)
{
return mod(x,2.0*M_PI)/(2.0*M_PI);
}
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
vec2 uv = fragCoord/iResolution.y;
uv.y=-uv.y;
init_noise();
float o = _o + uv.x*M_PI/2.0;
vec2 phasorNoise = eval_noise(uv,_f,_b,o);
float Phi = atan(phasorNoise.y,phasorNoise.x);
fragColor = vec4(vec3(PWM(Phi,0.5+0.4*cos(iTime)*(0.1+0.9*uv.x))),1.0); // animated PWM
//fragColor = vec4(vec3(sin(Phi)*0.4+0.5),1.0); // sinewave
//fragColor = vec4(vec3(sawTooth(Phi)),1.0); //sawtooth
//fragColor = vec4(vec3(square(Phi)),1.0); // square wave
}