.. highlightlang:: us

.. _poly_line_clip:

poly_line_clip
==============

.. index:: poly_line_clip

.. us.tag  poly_line_clip NOTREADYENGLISH base_graph New363

:ref:`poly_line_clip` calculates the intersections between two polygons.

.. index:: polygon clipping

.. function::  <rmXY, rmIDX> = poly_line_clip(nOption, clip, line)

.. us.return

**Return Value**

*rmXY*, *rmIDX*. The function returns two values. The return value *rmXY*
is a matrix with two columns. The first column contains the x-coordinates and the
second column the y_coordinates. It contains the original coordinates and the
intersection points. The return value *rmIDX* is a matrix with two columns
The first column contains the start index and the second column the end index
of the line segment. For each segment the index matrix contains one row. If the
line is completely outside or inside the clip polygon the return value *rmIDX*
has only one element. If the value is 1 the polygon is completely inside. If the
value is 0 the polygon is completely outside.
.. us.params

**Parameters**

.. uparam:: nOption

   *nOption*: 0 == inside, 1 == outside.

.. uparam:: clip

   *clip* are the x/y-coordinates of the clip polygon. The coordinates must
   be given as a complex vector (x + 1i*y) (see example).

.. uparam:: line

   *line* are the x/y-coordinates of the subject polygon. The coordinates must
   be given as a complex vector (x + 1i*y) (see example).

.. us.example

**Example**

.. image:: S:/uniplot-obj/images/poly_line_clip.*

::

   def test(option)
   {
       idx = poly_hull(x = rand(1,1000), y = rand(1,1000))
       h = plot(x[idx], y[idx])
       h2 = plot(x, y, h[2])
       XYShowLine(h2[3], FALSE)
       clip = x[idx] + 1i*y[idx];
       subject = [0,1] + 1i* [0,1];
       <xy, idx> = poly_line_clip(option, clip, subject);
       print "xy:", xy, "idx", idx
       if (len(idx) == 1) {
           if (idx[1] == 1) {
               // draw complete line!
               plot(xy[;1], xy[;2], h[2]);
               return TRUE;
           } else {
               // all points outside!
               return TRUE;
           }
       } else {
           for (i in 1:nr(idx)) {
               plot(xy[idx[i;];1], xy[idx[i;];2], h[2])
           }
       }
       LayerSetAxisMinMaxDelta(h2[2], "X", -0.1, 1.1, 0.1)
       LayerSetAxisMinMaxDelta(h2[2], "Y", -0.1, 1.1, 0.1)
       LayerShowGrid(h2[2], "X", FALSE, FALSE)
       LayerShowGrid(h2[2], "Y", FALSE, FALSE)
       LayerSetAxisTitle(h2[2], "X", "")
       LayerSetAxisTitle(h2[2], "Y", "")
       PageReplot(h2[1])
   }

.. seealso::
   :ref:`poly_poly_clip`

:sub:`id-12861`