A tessellation unit of a graphics processing unit (GPU) determines domain coordinates for vertices of a received primitive. The tessellation unit outputs the determined domain coordinates for the vertices. The tessellation unit further determines that a domain type for the received primitive is not one of tri, isoline, or quad domain, and outputs information indicative of a graphical feature associated with one or more of the determined domain coordinates when the domain type is not one of the tri, isoline, or quad domain.