// FilmBurn — generated from https://github.com/gl-transitions/gl-transitions/blob/master/transitions/FilmBurn.glsl
// Author: Anastasia Dunbar
// License: MIT
// Description: Glowing film-burn light leaks wash over the image and reveal the incoming one

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 Seed; 
float sigmoid(float x, float a) {
    float b = pow(x*2.,a)/2.;
    if (x > .5) {
        b = 1.-pow(2.-(x*2.),a)/2.;
    }
	return b;
}
float rand(float co){
    return fract(sin((co*24.9898)+Seed)*43758.5453);
}
float rand(vec2 co){
    return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
}
float apow(float a,float b) { return pow(abs(a),b)*sign(b); }
vec3 pow3(vec3 a,vec3 b) { return vec3(apow(a.r,b.r),apow(a.g,b.g),apow(a.b,b.b)); }
float smooth_mix(float a,float b,float c) { return mix(a,b,sigmoid(c,2.)); }
float random(vec2 co, float shft){
    co += 10.;
    return smooth_mix(fract(sin(dot(co.xy ,vec2(12.9898+(floor(shft)*.5),78.233+Seed))) * 43758.5453),fract(sin(dot(co.xy ,vec2(12.9898+(floor(shft+1.)*.5),78.233+Seed))) * 43758.5453),fract(shft));
}
float smooth_random(vec2 co, float shft) {
	return smooth_mix(smooth_mix(random(floor(co),shft),random(floor(co+vec2(1.,0.)),shft),fract(co.x)),smooth_mix(random(floor(co+vec2(0.,1.)),shft),random(floor(co+vec2(1.,1.)),shft),fract(co.x)),fract(co.y));
}
vec4 blendedColor(vec2 p) {
    return mix(getFromColor(p), getToColor(p), sigmoid(progress,10.));
}

vec4 transition(vec2 p) {
  vec3 f = vec3(0.);
  for (float i = 0.; i < 13.; i++) {
    f += sin(((p.x*rand(i)*6.)+(progress*8.))+rand(i+1.43))*sin(((p.y*rand(i+4.4)*6.)+(progress*6.))+rand(i+2.4));
    f += 1.-clamp(length(p-vec2(smooth_random(vec2(progress*1.3),i+1.),smooth_random(vec2(progress*.5),i+6.25)))*mix(20.,70.,rand(i)),0.,1.);
  }
  f += 4.;
  f /= 11.;
  f = pow3(f*vec3(1.,0.7,0.6),vec3(1.,2.-sin(progress*3.14159265358979323),1.3));
  f *= sin(progress*3.14159265358979323);
  
  p -= .5;
  p *= 1.+(smooth_random(vec2(progress*5.),6.3)*sin(progress*3.14159265358979323)*.05);
  p += .5;
  
  vec4 blurred_image = vec4(0.);
  float bluramount = sin(progress*3.14159265358979323)*.03;

  for (float i = 0.; i < 50.; i++) { 
      vec2 q = vec2(cos(degrees((i/50.)*360.)),sin(degrees((i/50.)*360.))) *  (rand(vec2(i,p.x+p.y))+bluramount); 
      vec2 uv2 = p+(q*bluramount);
      blurred_image += blendedColor(uv2);
  }
  blurred_image /= 50.;
  
  return blurred_image+vec4(f,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);
}