// Box — generated from https://github.com/gl-transitions/gl-transitions/blob/master/transitions/Box.glsl
// Author: lql
// License: MIT
// Description: The outgoing image shrinks into a box, toward the center or a corner, revealing 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 int rectIn; 

uniform int location; 

vec4 transition(vec2 uv) {
    float p = rectIn == 1 ? 1.0 - progress : progress;
    float x1, y1, x2, y2;

    
    if (location == 0) {
        x1 = y1 = 0.5 * (1.0 - p);
        x2 = y2 = 1.0 - x1;
    } else {
        
        x1 = (location == 1 || location == 2) ? 0.0 : 1.0 - p;
        y1 = (location == 1 || location == 3) ? 1.0 - p : 0.0;
        x2 = (location == 1 || location == 2) ? p : 1.0;
        y2 = (location == 1 || location == 3) ? 1.0 : p;
    }

    
    float in_rect = step(x1, uv.x) * step(uv.x, x2) * step(y1, uv.y) * step(uv.y, y2);
    in_rect = rectIn == 1 ? 1.0 - in_rect : in_rect;

    
    return mix(getFromColor(uv), getToColor(uv), in_rect);
}

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);
}