from steveroll over @ discord

shockwave.glsl

extern number minRadius = 0.05;
  extern number maxRadius = 0.1;
  
  extern number mul = 0.01;
  
  extern vec2 center = vec2(0.5,0.5);
  
  number dist(vec2 a, vec2 b){
    return sqrt(pow(b.x-a.x,2)+pow(b.y-a.y,2));
  }
  
  vec4 effect(vec4 color, Image tex, vec2 tc, vec2 sc){
    number d = dist(tc,center);
    if(d >= minRadius && d <= maxRadius){
      number td = 1-abs((d-minRadius)/(maxRadius-minRadius)-0.5)*2;
      tc.y += td*mul;
    }
    return Texel(tex, tc) * color;
  }