Back to shaders
Shader test bench
Ink Diffusion Bloom
runnable fragment
Complete GLSL fragment shader. Stronghold runs it directly when the browser can compile it.
Code
precision mediump float;
uniform vec2 resolution;
uniform float time;
float hash(vec2 p){return fract(sin(dot(p,vec2(77.7,33.3)))*43758.5453);}
float noise(vec2 p){vec2 i=floor(p),f=fract(p);f=f*f*(3.0-2.0*f);return mix(mix(hash(i),hash(i+vec2(1,0)),f.x),mix(hash(i+vec2(0,1)),hash(i+1.0),f.x),f.y);}
float fbm(vec2 p){float v=0.0,a=0.5;for(int i=0;i<6;i++){v+=a*noise(p);p*=2.02;a*=0.52;}return v;}
void main(){
vec2 uv=(gl_FragCoord.xy-0.5*resolution.xy)/min(resolution.x,resolution.y);
float n=fbm(uv*3.0+vec2(time*0.04,-time*0.03));
float rings=sin((length(uv)+n*0.28-time*0.04)*32.0);
float ink=smoothstep(0.2,0.95,n+0.25*rings);
vec3 paper=vec3(0.92,0.86,0.74);
vec3 dye=mix(vec3(0.05,0.03,0.12),vec3(0.35,0.03,0.24),n);
gl_FragColor=vec4(mix(paper,dye,ink),1.0);
}