#iChannel0 "https://i.imgur.com/TnmUwCn.jpg"

float SQRT3 = 1.73205080757;

float HexDist(vec2 p) {
    p = abs(p);
    float c = dot(p, normalize(vec2(1,SQRT3)));
    c = max(c, p.x);
    return c;
}

vec4 HexCoords(vec2 uv) {
    vec2 r = vec2(1, SQRT3);
    vec2 h = r/2.0;

    vec2 a = mod(uv, r)-h;
    vec2 b = mod(uv-h, r)-h;
    vec2 gv = length(a) < length(b) ? a : b;

    vec2 id = uv-gv;
    //standard uv
    return vec4(gv.x, gv.y, id.x, id.y);
     
    // polar coord uv
    // float x = atan(gv.y, gv.x);
    // float y = HexDist(gv);
    // return vec4(x, y, id.x, id.y);


    // polar coord 2 uv
    // float x = atan(gv.y, gv.x);
    // float y = 0.5-HexDist(gv);
    // return vec4(x, y, id.x, id.y);
}

void mainImage ( out vec4 fragColor, in vec2 fragCoord) {
    vec2 uv = (fragCoord-0.5*iResolution.xy)/iResolution.y;
    
    vec3 col = vec3(0.0);
    uv *= 10.0;
    
    vec4 hc = HexCoords(uv);
    //col.rg = hc(uv).xy;
    col.rgb = texture(iChannel0, hc(uv).xy+0.5).rgb;
    col.rgb *= vec3(smoothstep(0.09, 0.99, sin(hc.z+hc.w/17.+iTime) ));

    fragColor = vec4(col, 1.0);
}