Previous: carg Up: ../plot79_c.html Next: clp3d

CLP2D

       SUBROUTINE  CLP2D (U1,V1,MOVED1, U2,V2,MOVED2, VISSEG)
 C$    (2-Dimensional Unit Square Clip)
 C$    Clip  a   line  segment   defined  by   its  endpoints   in
 C$    2-dimensional curvilinear coordinates  to the unit  square.
 C$    The arguments are:
 C$
 C$    (U1,V1)........Curvilinear coordinates of point 1.
 C$    MOVED1.........LOGICAL value set .TRUE. if point 1 is moved.
 C$    (U2,V2)........Curvilinear coordinates of point 2.
 C$    MOVED2.........LOGICAL value set .TRUE. if point 2 is moved.
 C$    VISSEG.........LOGICAL value set .TRUE. if  the  segment is
 C$                   visible.  If VISSEG=.FALSE., then the values
 C$                   of   all   preceding   parameters   may   be
 C$                   undefined.
 C$
 C$    This routine is  adapted from the  general polyhedral  clip
 C$    routine, CLPPH (written by  John Halleck of the  University
 C$    of Utah  Computing Center),  for the  special case  of  2-D
 C$    curvilinear coordinates on the  unit square, for which  the
 C$    inward-pointing  edge  normals  are  (1,0,0,0),  (0,1,0,0),
 C$    (-1,0,0,1),and (0,-1,0,1).
 C$    (07-JAN-82)