// zoomInOut — GLSL ES 3.00, generated from https://github.com/gl-transitions/gl-transitions/blob/master/transitions/zoomInOut.glsl
// Author: OllyOllyOlly
// License: MIT
// Description: Zooms into the outgoing image until it blurs into a flat color, then out to the incoming one
// Tags: zoom, blur

vec2 zoom(vec2 uv, float amount) {
  return 0.5 + ((uv - 0.5) * (1.0 - amount));
}

vec4 transition (vec2 uv) {
  float zoomFrom = smoothstep(0.0, 1.0, progress * 2.0);
  float zoomTo = smoothstep(0.0, 1.0, (1.0 - progress) * 2.0);
  float crossfade = smoothstep(0.4, 0.6, progress);
  return mix(
    getFromColor(zoom(uv, zoomFrom)),
    getToColor(zoom(uv, zoomTo)),
    crossfade
  );
}