1Polypack(3NCARG)                 NCAR GRAPHICS                Polypack(3NCARG)
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NAME

6       Polypack - a set of routines allowing polygons to be manipulated in
7       various ways. Each of the six principal routines is given a "clip"
8       polygon, a "subject" polygon, and a workspace; it operates on the two
9       polygons in some way to create either a derivative polygon or a set of
10       trapezoids representing the interior of that derivative polygon and
11       then passes these on to a user-specified processing routine.
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SYNOPSIS

14       PPDIPO - generates and returns the boundary of the "difference"
15       polygon, which consists of all points that are inside the subject
16       polygon but not inside the clip polygon.
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18       PPINPO - generates and returns the boundary of the "intersection"
19       polygon, which consists of all points that are inside both the clip
20       polygon and the subject polygon.
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22       PPUNPO - generates and returns the boundary of the "union" polygon,
23       which consists of all points that are inside either or both of the clip
24       polygon and the subject polygon.
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26       PPDITR - generates and returns a set of trapezoids representing the
27       interior of the "difference" polygon, which consists of all points that
28       are inside the subject polygon but not inside the clip polygon.
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30       PPINTR - generates and returns a set of trapezoids representing the
31       interior of the "intersection" polygon, which consists of all points
32       that are inside both the clip polygon and the subject polygon.
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34       PPUNTR - generates and returns a set of trapezoids representing the
35       interior of the "union" polygon, which consists of all points that are
36       inside either or both of the clip polygon and the subject polygon.
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38       PPPPAP - can be called to preprocess a polygon in such a way as to
39       remove certain peculiarities that can cause minor cosmetic errors in
40       the output from the routines that return trapezoids.
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42       PPPLCL - clips a polyline against a clipping rectangle. It is intended
43       that, eventually, there should be a better routine that will clip a
44       polyline against an arbitrary polygon, but that routine has not yet
45       been written.
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C-BINDING SYNOPSIS

48       #include <ncarg/ncargC.h>
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50       c_ppdipo
51       c_ppditr
52       c_ppinpo
53       c_ppintr
54       c_ppplcl
55       c_ppppap
56       c_ppunpo
57       c_ppuntr
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ACCESS

60       To use Polypack routines, load the NCAR Graphics libraries ncarg,
61       ncarg_gks, and ncarg_c, preferably in that order.
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MESSAGES

64       None.  All error conditions in Polypack routines are reported by means
65       of an error-flag argument.
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SEE ALSO

68       Online: ppdipo, ppditr, ppinpo, ppintr, ppplcl, ppppap, ppunpo, ppuntr,
69       ncarg_cbind.
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71       Hardcopy: None.
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74       Copyright (C) 1987-2009
75       University Corporation for Atmospheric Research
76       The use of this Software is governed by a License Agreement.
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80UNIX                              March 1995                  Polypack(3NCARG)
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