Pixel distance from mouse pointer to a 3D disc.
public static float DistanceToDisc(Vector3 center, Vector3 normal, float radius) { Vector3 from = Vector3.Cross(normal, Vector3.up); if (from.sqrMagnitude < 0.001f) { from = Vector3.Cross(normal, Vector3.right); } return DistanceToArc(center, normal, from, 360f, radius); }