// Mixes color with luma-coefficient grayscale

vec3 colorMix(vec3 color, float time) {

    float gray = dot(color, vec3(0.2126, 0.7152, 0.0722));

    return mix(vec3(gray), color, time);

}

// Main

void main(void) {

    float time = fract(u_time/u_duration);

    vec4 texture = texture2D(u_texture, v_tex_coord);

    // Mixed color

    vec3 color = colorMix(texture.rgb, time);

    float num = sin(360.0*(1.0-time))*256.0;

    float line = floor(num*v_tex_coord.y);

    float bin = mod(line, 2.0);

    vec4 almost = mix(vec4(color, texture.a)*time, texture*vec4(bin), bin);

    if (almost.a <= 0.2) {

        almost.a = 0.0;

    }

    gl_FragColor = vec4(almost.rgb + vec3(0,(1.0-time)*0.25,(1.0-time)*0.5) * almost.a, almost.a);

}