precision highp float;

varying vec2 textureCoordinate;
uniform sampler2D from;
uniform sampler2D to;
uniform float progress;

vec4 getFromColor(vec2 uv) {
	return texture2D(from,uv);
}

vec4 getToColor(vec2 uv){
	return texture2D(to,uv);
}
const float strength = 0.1;

vec4 transition(vec2 p) {
  vec4 ca = getFromColor(p);
  vec4 cb = getToColor(p);
  
  vec2 oa = (((ca.rg+ca.b)*0.5)*2.0-1.0);
  vec2 ob = (((cb.rg+cb.b)*0.5)*2.0-1.0);
  vec2 oc = mix(oa,ob,0.5)*strength;
  
  float w0 = progress;
  float w1 = 1.0-w0;
  return mix(getFromColor(p+oc*w0), getToColor(p-oc*w1), progress);
}
void main(){
	gl_FragColor = transition(textureCoordinate);
}