ripple.glsl

#ifdef GL_ES
precision highp float;
#endif

// General parameters
uniform sampler2D from;
uniform sampler2D to;
uniform float progress;
uniform vec2 resolution;

uniform float amplitude;
uniform float speed;

void main()
{
  vec2 p = gl_FragCoord.xy / resolution.xy;
  vec2 dir = p - vec2(.5);
  float dist = length(dir);
  vec2 offset = dir * (sin(progress * dist * amplitude - progress * speed) + .5) / 30.;
  gl_FragColor = mix(texture2D(from, p + offset), texture2D(to, p), smoothstep(0.2, 1.0, progress));
}

uniforms.default.json

{ "amplitude": 100, "speed": 50 }