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 inch/degree, 1:xxxxx, or
           width in inch (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)
           -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)
           -Jllon0/lat0/lat1/lat2/scale (Lambert)

           MISCELLANEOUS PROJECTIONS:

           -Jhlon0/scale (Hammer)
           -Jilon0/scale (Sinusoidal)
           -Jklon0/scale (Eckert VI)
           -Jnlon0/scale (Robinson)
           -Jrlon0/scale (Winkel Tripel)
           -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 inch [Default is (-0.75i/-
           0.75i)].  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) inch  [Default is
           (a1i,a1i) 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