// GlitchMemories — generated from https://github.com/gl-transitions/gl-transitions/blob/master/transitions/GlitchMemories.glsl
// Author: Gunnar Roth
// License: MIT
// Description: A crossfade with glitchy, color-shifted blocks

uniform shader _from;
uniform shader _to;
uniform float2 _resolution;
uniform float progress;
uniform float ratio;

vec4 getFromColor(vec2 uv) { return vec4(unpremul(_from.eval(vec2(uv.x, 1.0 - uv.y) * _resolution))); }
vec4 getToColor(vec2 uv) { return vec4(unpremul(_to.eval(vec2(uv.x, 1.0 - uv.y) * _resolution))); }

vec4 transition(vec2 p) {
  vec2 block = floor(p.xy / vec2(16));
  vec2 uv_noise = block / vec2(64);
  uv_noise += floor(vec2(progress) * vec2(1200.0, 3500.0)) / vec2(64);
  vec2 dist = progress > 0.0 ? (fract(uv_noise) - 0.5) * 0.3 *(1.0 -progress) : vec2(0.0);
  vec2 red = p + dist * 0.2;
  vec2 green = p + dist * .3;
  vec2 blue = p + dist * .5;

  return vec4(mix(getFromColor(red), getToColor(red), progress).r,mix(getFromColor(green), getToColor(green), progress).g,mix(getFromColor(blue), getToColor(blue), progress).b,1.0);
}

half4 main(float2 _coord) {
  vec2 _uv = _coord / _resolution;
  vec4 _c = clamp(transition(vec2(_uv.x, 1.0 - _uv.y)), 0.0, 1.0);
  return half4(_c.rgb * _c.a, _c.a);
}