// Sample SDF (black=inside, white=outside)
float dist = 1.0 - texture2D(sdfTexture, uv).r;

// Anti-aliased edge
float edge = 0.5;
float delta = fwidth(dist) * 0.5;
float alpha = smoothstep(edge - delta, edge + delta, dist);

// Outline effect
float outline = smoothstep(0.45, 0.5, dist)
             - smoothstep(0.5, 0.55, dist);