/// <summary>
/// Determine whether given 2D point lies within
/// the polygon.
///
/// Written by Jeremy Tammik, Autodesk, 2009-09-23,
/// based on code that I wrote back in 1996 in C++,
/// which in turn was based on C code from the
/// article "An Incremental Angle Point in Polygon
/// Test" by Kevin Weiler, Autodesk, in "Graphics
/// Gems IV", Academic Press, 1994.
///
/// Copyright (C) 2009 by Jeremy Tammik. All
/// rights reserved.
///
/// This code may be freely used. Please preserve
/// this comment.
/// </summary>
public bool PolygonContains(
UVArray polygon,
UV point)
{
// initialize
Quadrant quad = GetQuadrant(
polygon.get_Item(0), point);
Quadrant angle = 0;
// loop on all vertices of polygon
Quadrant next_quad, delta;
int n = polygon.Size;
for (int i = 0; i < n; ++i)
{
UV vertex = polygon.get_Item(i);
UV next_vertex = polygon.get_Item(
(i + 1 < n) ? i + 1 : 0);
// calculate quadrant and delta from last quadrant
next_quad = GetQuadrant(next_vertex, point);
delta = next_quad - quad;
AdjustDelta(
ref delta, vertex, next_vertex, point);
// add delta to total angle sum
angle = angle + delta;
// increment for next step
quad = next_quad;
}
// complete 360 degrees (angle of + 4 or -4 )
// means inside
return((angle == +4) || (angle == -4));
// odd number of windings rule:
// if (angle & 4) return INSIDE; else return OUTSIDE;
// non-zero winding rule:
// if (angle != 0) return INSIDE; else return OUTSIDE;
}
public bool PolyGonContains(List <XYZ> xyZArray, XYZ p1)
{
UVArray uva = new UVArray(xyZArray);
return(PolygonContains(uva, p1.TOUV()));
}
