394 Chapter 8 Collision Detection
when D is replaced by the opposite direction −D.Thisfollowsfromλ
min
(−D) =
−λ
max
(D) and λ
max
(−D) =−λ
min
(D). When D is not unit length, the intervals ob-
tained for the separating line tests are not the projections of the object onto the line;
rather, they are scaled versions of the projection intervals. We make no distinction
between the scaled projection and regular projection. We w ill also use the terminol-
ogy that the direction vector for a separating line is called a separating direction,a
direction that is not necessarily unit length.
Please note that in two dimensions, the terminology of a separating line or axis
is potentially confusing. The separating line separates the projections of the objects
on that