## NAME

          psclip - To set up polygonal clip paths

## SYNOPSIS

          psclip xyfiles -Jparameters -Rwest/east/south/north[r] [ -Btickinfo ] [
          -Eaz/el ] [ -K ] [ -N ] [ -M[flag] ] [ -O ] [ -P ] [ -U[/dx/dy/][label]
          ] [ -V ] [ -Xx-shift ] [ -Yy-shift ] [ -Zzlevel ] [ -ccopies ] [ -: ] [
          -bi[s][n] ]

          psclip -C [ -K ] [ -O ]

## DESCRIPTION

          psclip reads (x,y) file(s) [or standard input] and draws polygons that
          are activated as clipping paths.  Several files may be read to create
          complex paths consisting of several non-connecting segments.  As an
          option (-N), the user may choose to reverse the sense of what is the
          inside and outside of the paths.  After subsequent plotting, which
          will be clipped against these paths, the clipping may be deactivated
          by running psclip a second time with the -C option only.

          xyfiles
               ASCII [or binary, see -b] file(s) with (x,y) values for clip
               polygons.  If no files are given, the standard input is read.

          -C   Mark end of existing clip path.  No input file or projection
               information are needed.

          -J   Selects the map projection. Scale is cm/degree, 1:xxxxx, or width
               in cm (upper case modifier).

               CYLINDRICAL PROJECTIONS:

               -Jclon0/lat0/scale (Cassini)
               -Jjlon0/scale (Miller)
               -Jmscale (Mercator - Greenwich and Equator as origin)
               -Jmlon0/lat0/scale (Mercator - Give meridian and standard
               parallel)
               -Joalon0/lat0/azimuth/scale (Oblique Mercator - point and
               azimuth)
               -Joblon0/lat0/lon1/lat1/scale (Oblique Mercator - two points)
               -Joclon0/lat0/lonp/latp/scale (Oblique Mercator - point and pole)
               -Jqlon0/scale (Equidistant Cylindrical Projection (Plate Carree))
               -Jtlon0/scale (TM - Transverse Mercator, with Equator as y = 0)
               -Jtlon0/lat0/scale (TM - Transverse Mercator, set origin)
               -Juzone/scale (UTM - Universal Transverse Mercator)
               -Jylon0/lats/scale (Basic Cylindrical Projection)

               AZIMUTHAL PROJECTIONS:

               -Jalon0/lat0/scale (Lambert).
               -Jelon0/lat0/scale (Equidistant).
               -Jflon0/lat0/horizon/scale (Gnomonic).
               -Jglon0/lat0/scale (Orthographic).
               -Jslon0/lat0/scale (General Stereographic)

               CONIC PROJECTIONS:

               -Jblon0/lat0/lat1/lat2/scale (Albers)
               -Jdlon0/lat0/lat1/lat2/scale (Equidistant)
               -Jllon0/lat0/lat1/lat2/scale (Lambert)

               MISCELLANEOUS PROJECTIONS:

               -Jhlon0/scale (Hammer)
               -Jilon0/scale (Sinusoidal)
               -Jk[f|s]lon0/scale (Eckert IV (f) and VI (s))
               -Jnlon0/scale (Robinson)
               -Jrlon0/scale (Winkel Tripel)
               -Jvlon0/scale (Van der Grinten)
               -Jwlon0/scale (Mollweide)

               NON-GEOGRAPHICAL PROJECTIONS:

               -Jpscale (Linear projection for polar (theta,r) coordinates)
               -Jxx-scale[l|ppow][/y-scale[l|ppow]] (Linear, log, and power
               scaling)
               More details can be found in the psbasemap manpages.

          -R   west, east, south, and north specify the Region of interest.  To
               specify boundaries in degrees and minutes [and seconds], use the
               dd:mm[:ss] format.  Append r if lower left and upper right map
               coordinates are given instead of wesn.

## OPTIONS

          No space between the option flag and the associated arguments

          -B   Sets map boundary tickmark intervals. See psbasemap for details.

          -E   Sets the viewpoint's azimuth and elevation [180/90]

          -H   Input file(s) has Header record(s).  Number of header records can
               be changed by editing your .gmtdefaults file.  If used, GMT
               default is 1 header record.

          -K   More PostScript code will be appended later [Default terminates
               the plot system].

          -M   Multiple segment file.  Segments are separated by a record whose
               first character is <flag>.  [Default is '>'].

          -N   Invert the sense of what is inside and outside, i.e., use the
               outside of the polygons for clipping.

          -O   Selects Overlay plot mode [Default initializes a new plot
               system].

          -P   Selects Portrait plotting mode [GMT Default is Landscape, see
               gmtdefaults to change this].

          -U   Draw Unix System time stamp on plot.  User may specify where the
               lower left corner of the stamp should fall on the page relative
               to lower left corner of plot in cm [Default is (-2c/-2c)].
               Optionally, append a label, or c (which will plot the command
               string.)

          -V   Selects verbose mode, which will send progress reports to stderr
               [Default runs "silently"].

          -X -Y
               Shift origin of plot by (x-shift,y-shift) cm  [Default is
               (a2.5c,a2.5c) for new plots, (0,0) for overlays].  Prepend a for
               absolute coordinates; the default (r) will reset plot origin.

          -Z   For 3-D projections:  Sets the z-level of the polygons [0].

          -:   Toggles between (longitude,latitude) and (latitude,longitude)
               input/output.  [Default is (longitude,latitude)].

          -c   Specifies the number of plot copies. [Default is 1]

          -bi  Selects binary input.  Append s for single precision [Default is
               double].  Append n for the number of columns in the binary
               file(s).  [Default is 2 input columns].

## EXAMPLES

          To make an overlay PostScript file that will set up a complex clip
          area to which subsequent plotting will be confined to, try:

          psclip my_region.xy -R0/40/0/40 -Jm0.3i -O -K > clip_mask_on.ps

          To deactivate the clipping in an existing plotfile, run:

          psclip -C -O >> complex_plot.ps

## SEE ALSO

          gmt, grdmask, psbasemap, psmask