NAME

clipline - clip a set of lines

SYNOPSIS

C
long clipline(mask, n, preline, postline, index)
String mask;
long n;
Coord preline[][3], postline[][4];
Boolean index[];

FORTRAN
integer function clipli(mask, n, preln, postln, index)
character*(*) mask
integer n
real preln(3,n), postln(4,n*2)
logical index(n*2)

Pascal
function clipline( mask: String; n: integer;
var preline: Coord3array; var postline: Coord4array;
var Index: Boolarray ): integer;

DESCRIPTION

Clipline selectively enables a subset of the six clipping planes.  Mask is a string of characters specifying which clipping planes are enabled.  This string is chosen from ‘l’, ‘r’, ‘b’, ‘t’, ‘n’, and ‘f’ (capital letters may also be used), which represent the left, right, bottom, top, near, and far clipping planes.  Mask can name from one to six planes, in any order. 

Clipline assumes that preline describes a set of connected line segments.  It returns the number of vertices in the set of clipped lines.  The clipped vertices themselves are returned in postline, which should have room for up to 2×n vertices; the process of clipping can add up to n new vertices. 

Index is a boolean array that shows which line segments were clipped.  If index[i] = TRUE, some of the vertices have been clipped out and postline[i] should be reached with a move command rather than draw. 

SEE ALSO

clippoly, clippnt, screenpnt, transform

NOTE

This command can only be used in immediate mode. 

Version 2.3  —  July 04, 1985