# molten bismuth

​                                                                                

<iframe width="640" height="360" frameborder="0" src="https://www.shadertoy.com/embed/WdVXWy?gui=true&t=10&paused=true&muted=false" allowfullscreen></iframe>

    // created by florian berger (flockaroo) - 2019
    // License Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
    
    // single pass CFD - with some self consistency fixes
    
    // drawing the liquid
    
    // same fluid as in "Spilled" - https://www.shadertoy.com/view/MsGSRd
    // ...but with self-consistent-ish velocity field
    // the previous method was just defined implicitely by the rotations on multiple scales
    // here the calculated velocity field is put back into the stored field
    
    // use mouse to push fluid, press I to init
    
    #define Res  (iResolution.xy)
    
    #define RandTex iChannel1
    
    vec4 myenv(vec3 pos, vec3 dir, float period)
    {
        return texture(iChannel2,dir.xzy)+.15;
    }
    
    vec4  getCol(vec2 uv) { return texture(iChannel0,scuv(uv)); }
    float getVal(vec2 uv) { return length(getCol(uv).xyz); }
        
    vec2 getGrad(vec2 uv,float delta)
    {
        vec2 d=vec2(delta,0); return vec2( getVal(uv+d.xy)-getVal(uv-d.xy),
                                           getVal(uv+d.yx)-getVal(uv-d.yx) )/delta;
    }
    
    void mainImage( out vec4 fragColor, in vec2 fragCoord )
    {
    	vec2 uv = fragCoord.xy / iResolution.xy;
        
    // calculate normal from gradient (the faster the higher)
    vec3 n = vec3(-getGrad(uv,1.4/iResolution.x)*.02,1.);
    n=normalize(n);
    
    /*vec3 light = normalize(vec3(-1,1,2));
    float diff=clamp(dot(n,light),0.,1.0);
    float spec=clamp(dot(reflect(light,n),vec3(0,0,-1)),0.0,1.0); spec=exp2(log2(spec)*24.0)*2.5;*/
    
    // evironmental reflection
    vec2 sc=(fragCoord-Res*.5)/Res.x;
    vec3 dir=normalize(vec3(sc,-1.));
    vec3 R=reflect(dir,n);
    vec3 refl=myenv(vec3(0),R.xzy,1.).xyz;
    
    // slightly add velocityfield to color - gives it a bit of a 'bismuty' look
    vec4 col=getCol(uv)+.5;
    col=mix(vec4(1),col,.35);
    col.xyz*=.95+-.05*n; // slightly add some normals to color
    
    //fragColor.xyz = col.xyz*(.5+.5*diff)+.1*refl;
    fragColor.xyz = col.xyz*refl;
    fragColor.w=1.;
    }