simple MSDF shader

msdf.glsl

    float r = sample.r;
    float g = sample.g;
    float b = sample.b;
    float median = max(min(r, g), min(max(r, g), b));
    float signed_dist = median - 0.5;
    float d = fwidth(signed_dist);
    float opacity = smoothstep(-d, d, signed_dist);
    
    //apply opacity to final alpha
    color.a *= opacity;