Smooth Minimal

One of most commun one found : Quadratic :

code:smoothsmin.glsl

// quadratic polynomial

float smin( float a, float b, float k )

{

k *= 4.0;

float h = max( k-abs(a-b), 0.0 )/k;

return min(a,b) - h*h*k*(1.0/4.0);

}

Mix factor

code:smoothsmin_mixfactor.glsl

vec2 smin( float a, float b, float k )

{

float h = max( k-abs(a-b), 0.0 )/k;

float m = h*h*0.5;

float s = m*k*(1.0/2.0);

return (a<b) ? vec2(a-s,m) : vec2(b-s,1.0-m);

}

https://scrapbox.io/files/66c6dd5398da7e001de47f88.png