#ifdef GL_ES
precision mediump float;
precision mediump int;
#endif

uniform sampler2D u_texture;

uniform vec4 u_color;
uniform vec2 u_texsize;
uniform vec2 u_uv;
uniform vec2 u_uv2;
uniform float u_progress;
uniform float u_time;

varying vec4 v_color;
varying vec2 v_texCoord;

const float chunk = 4.0;
const float start = 0.7;
const float end = 0.9;

float rand(vec2 co){
    return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
}

float round(float f){
    return float(int(f / chunk)) * chunk;
}

bool id(vec2 coords, vec4 base, float basediff){
    vec4 target = texture2D(u_texture, coords);
    return target.a < 0.1 || (coords.x < u_uv.x || coords.y < u_uv.y || coords.x > u_uv2.x || coords.y > u_uv2.y);
}

bool cont(vec2 T, vec2 v, float basediff){
    float step = 1.0;
    vec4 base = texture2D(u_texture, T);
    return base.a > 0.1 &&
           		(id(T + vec2(0, step) * v, base, basediff) || id(T + vec2(0, -step) * v, base, basediff) ||
           		id(T + vec2(step, 0) * v, base, basediff) || id(T + vec2(-step, 0) * v, base, basediff));
}

bool complete(vec2 coords){
    vec2 rc = vec2(round(coords.x), round(coords.y));
    float r = clamp(rand(rc) + u_progress, 0.0, 1.0);
    float fr = (r-start)*(1.0/(end-start));

    vec2 next = rc + chunk/2.0;
    float rdst = max(abs(coords.x - next.x), abs(coords.y - next.y));
    return rdst / (chunk/2.0) < fr;
}

void main() {

	vec2 t = v_texCoord.xy;

	vec2 v = vec2(1.0/u_texsize.x, 1.0/u_texsize.y);

	bool any = false;

	vec2 coords = (v_texCoord-u_uv) / v;


	float value = coords.x + coords.y;

	vec4 color = texture2D(u_texture, t);
	vec2 rc = vec2(round(coords.x), round(coords.y));
	vec2 center = ((u_uv + u_uv2)/2.0 - u_uv) /v;

	float r = clamp(rand(rc) + u_progress, 0.0, 1.0);

    const float scl = 10.0;
	float dst = (abs(center.x - coords.x) + abs(center.y - coords.y)) / 2.0;

    if(dst - 1.0 < u_progress * (center.x) && dst> u_progress * (center.x) && color.a > 0.1){
        gl_FragColor = u_color;
    }else if(r > end){
        gl_FragColor = color;
    }else if((cont(t, v, 100.0) && mod(u_time / 1.5 + value, 20.0) < 5.0 && color.a > 0.1) ||
            (complete(coords) && (!complete(coords + vec2(1.0, 0.0)) || !complete(coords + vec2(-1.0, 0.0)) || !complete(coords + vec2(0.0, 1.0))
            || !complete(coords + vec2(0.0, -1.0))))){
       gl_FragColor = u_color;
	}else if(r > start && color.a > 0.1){
	    float fr = (r-start)*(1.0/(end-start));

	    vec2 next = rc + chunk/2.0;
	    float rdst = max(abs(coords.x - next.x), abs(coords.y - next.y));
	    if(rdst / (chunk/2.0) < fr){
	        gl_FragColor = u_color;
	    }else{
	        gl_FragColor = vec4(0.0);
	    }
	}else{
	    gl_FragColor = vec4(0.0);
	}
}