mat2 rot2d(float angle){return mat2(cos(angle),-sin(angle),sin(angle),cos(angle));} float r(float a, float b){return fract(sin(dot(vec2(a,b),vec2(12.9898,78.233)))*43758.5453);} float h(float a){return fract(sin(dot(a,dot(12.9898,78.233)))*43758.5453);}

float noise(vec3 x){ vec3 p = floor(x); vec3 f = fract(x); f = ff(3.0-2.0f); float n = p.x + p.y57.0 + 113.0*p.z; return mix(mix(mix( h(n+0.0), h(n+1.0),f.x), mix( h(n+57.0), h(n+58.0),f.x),f.y), mix(mix( h(n+113.0), h(n+114.0),f.x), mix( h(n+170.0), h(n+171.0),f.x),f.y),f.z); }

// http://www.iquilezles.org/www/articles/morenoise/morenoise.htm // http://www.pouet.net/topic.php?post=401468 vec3 dnoise2f(vec2 p){ float i = floor(p.x), j = floor(p.y); float u = p.x-i, v = p.y-j; float du = 30.uu*(u*(u-2.)+1.); float dv = 30.vv*(v*(v-2.)+1.); u=uuu*(u*(u6.-15.)+10.); v=vvv(v*(v6.-15.)+10.); float a = r(i, j ); float b = r(i+1.0, j ); float c = r(i, j+1.0); float d = r(i+1.0, j+1.0); float k0 = a; float k1 = b-a; float k2 = c-a; float k3 = a-b-c+d; return vec3(k0 + k1u + k2v + k3uv, du(k1 + k3v), dv(k2 + k3*u)); }

float fbm(vec2 uv){
vec2 p = uv; float f, dx, dz, w = 0.5; f = dx = dz = 0.0; for(int i = 0; i < 28; ++i){
vec3 n = dnoise2f(uv); dx += n.y; dz += n.z; f += w * n.x / (1.0 + dxdx + dzdz); w = 0.86; uv = vec2(1.16); uv = rot2d(1.25noise(vec3(p0.1, 0.12iTime))+ 0.75noise(vec3(p0.1, 0.20*iTime))); } return f; }

float fbmLow(vec2 uv){ float f, dx, dz, w = 0.5; f = dx = dz = 0.0; for(int i = 0; i < 4; ++i){
vec3 n = dnoise2f(uv); dx += n.y; dz += n.z; f += w * n.x / (1.0 + dxdx + dzdz); w *= 0.75; uv *= vec2(1.5); } return f; }

void mainImage(out vec4 fragColor, in vec2 fragCoord){ vec2 uv = 1.0-2.0*(fragCoord.xy / iResolution.xy); uv.y /= iResolution.x/iResolution.y; float t = iTime*0.6;

vec2 rv = uv/(length(uv*2.5)*(uv*30.0));
uv *= rot2d(0.3*t);
float val = 0.5*fbm(uv*2.0*fbmLow(length(uv)+rv-t));
uv *= rot2d(-0.6*t);

#ifdef INVERT
	fragColor = 1.0-1.2*vec4( vec3(0.5*fbm(uv*val*8.0)+0.02*r(uv.x,uv.y)), 1.0 );
#else
	fragColor = 1.6*vec4( vec3(0.5*fbm(uv*val*8.0)+0.02*r(uv.x,uv.y)), 1.0 );
#endif

fragColor.rgb *= 3.8;
fragColor.rgb = fragColor.rgb/(1.0+fragColor.rgb);
fragColor.rgb = smoothstep(0.18, 0.88, fragColor.rgb);

}