// Overexposure — generated from https://github.com/gl-transitions/gl-transitions/blob/master/transitions/Overexposure.glsl
// Author: Ben Zhang
// License: MIT
// Description: A crossfade through a washed-out, overexposed white

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))); }

uniform float strength; 
const float PI = 3.141592653589793;

vec4 transition (vec2 uv) {
  vec4 from = getFromColor(uv);
  vec4 to = getToColor(uv);

  
  float from_m = 1.0 - progress + sin(PI * progress) * strength;
  float to_m = progress + sin(PI * progress) * strength;
  
  return vec4(
    from.r * from.a * from_m + to.r * to.a * to_m,
    from.g * from.a * from_m + to.g * to.a * to_m,
    from.b * from.a * from_m + to.b * to.a * to_m,
    mix(from.a, to.a, progress)
  );
}

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);
}