have equal surface (i.e., are continuous) on the envelope.
This enables the removal of comparison between lists of surfaces, thus
the removal of "operator < for xy-monotone surface" from the traits concept
(when not using any cache).
have equal surface (i.e., are continuous) on the envelope.
This enables the removal of comparison between lists of surfaces, thus
the removal of "operator < for xy-monotone surface" from the traits concept
(when not using any cache).