ISF - Shadertoy - SatisSpiraling
#define pi 3.141592653589793
#define PALETTE vec3(.0, 1.4, 2.)+1.5
float aspect = RENDERSIZE.x/RENDERSIZE.y;
float w = 50./sqrt(RENDERSIZE.x*aspect+RENDERSIZE.y);
float T = TIME * rate;
mat2 mm2(in float a){float c = cos(a), s = sin(a);return mat2(c,-s,s,c);}
float tri(in float x){return abs(fract(x)-.5);}
vec2 tri2(in vec2 p){return vec2(tri(p.x+tri(p.y*2.)),tri(p.y+tri(p.x*2.)));}
mat2 m2 = mat2( 0.970, 0.242, -0.242, 0.970 );
float triangleNoise(in vec2 p) {
float z=1.5;
float z2=1.5;
float rz = 0.;
vec2 bp = p;
for (float i=0.; i<=3.; i++ ) {
vec2 dg = tri2(bp*2.)*.8;
dg *= mm2(T*.3);
p += dg/z2;
bp *= 1.6;
z2 *= .6;
z *= 1.8;
p *= 1.2;
p*= m2;
rz+= (tri(p.x+tri(p.y)))/z;
}
return rz;
}
void main() {
vec2 p = isf_FragNormCoord.xy*2.-1.;
p.x *= aspect;
p*= 1.05;
vec2 bp = p;
if (rotate) p *= mm2(T*.25);
float lp = length(p);
float id = floor(lp*loops+.5)/loops;
if (offset) p *= mm2(id*11.);
if (mirror) p.y = abs(p.y);
vec2 plr = vec2(lp, atan(p.y, p.x));
float rz = 1.-pow(abs(sin(plr.x*pi*loops))*1.25/pow(w,0.25),2.5);
float enp = plr.y+sin((T+id*5.5))*1.52-1.5;
rz *= smoothstep(0., 0.05, enp);
rz *= smoothstep(0.,.022*w/plr.x, enp)*step(id,1.);
if (mirror) rz *= smoothstep(-0.01,.02*w/plr.x,pi-plr.y);
if (noise) rz *= (triangleNoise(p/(w*w))*0.9+0.4);
vec3 col = (sin(PALETTE+id*5.+T)*0.5+0.5)*rz;
if (noise) col += smoothstep(.4,1.,rz)*0.15, col *= smoothstep(.2,1.,rz)+1.;
else col *= smoothstep(.8,1.15,rz)*.7+.8;
gl_FragColor = vec4(col,1.0);
}