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

uniform sampler2D u_texture;

uniform vec4 u_color;
uniform vec2 u_texsize;
uniform float u_time;
uniform vec2 u_offset;

varying vec4 v_color;
varying vec2 v_texCoord;

void main() {

    vec2 T = v_texCoord.xy;
    vec2 coords = (T * u_texsize) + u_offset;
    
    float si = 1.0 + sin(u_time / 20.0 /*+ (coords.x + coords.y) / 30.0*/) / 8.0;
	
	vec4 color = texture2D(u_texture, T) * vec4(si, si, si, 1.0);

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

	bool any = false;

	float thickness = 1.0;
	float step = 1.0;

	if(texture2D(u_texture, T).a < 0.1 && 
		(texture2D(u_texture, T + vec2(0, step) * v).a > 0.1 || texture2D(u_texture, T + vec2(0, -step) * v).a > 0.1 ||
		texture2D(u_texture, T + vec2(step, 0) * v).a > 0.1 || texture2D(u_texture, T + vec2(-step, 0) * v).a > 0.1))
		any = true;

	if(any){
		gl_FragColor = u_color * vec4(si, si, si, 1.0);
	}else{
	    
	    //coords.x = float(int(coords.x));
	    if(color.a > 0.1){
	        if(mod(coords.x + coords.y + sin(coords.x / 5.0) * 3.0 + sin(coords.y / 5.0) * 3.0  + u_time / 4.0, 10.0) < 2.0){
	            color *= 1.65;
	        }
	        
	        color.a = 0.18;
	    }
	    
		gl_FragColor = color;
	}
}