INSIDE
The purpose of this function is to indicate whether a specified 2D point is inside (returns a 1) a specified 2D polygon or outside (returns a 0).
FANNING SOFTWARE CONSULTING David Fanning, Ph.D. 1645 Sheely Drive Fort Collins, CO 80526 USA Phone: 970-221-0438 E-mail: david@idlcoyote.com Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Utility.
result = INSIDE(x, y, xpts, ypts)
x: A scalar or vector of the x coordinates of the 2D point(s) to check. y: A scalar or vector of the y coordinates of the 2D point(s) to check. xpts: The x coordinates of the 2D polygon. ypts: The y coordinates of the 2D polygon.
result: A scalar or vector set to 1 if the point is inside the polygon and to 0 if the point is outside the polygon.
INDEX: An output keyword. If set to a named variable, will return the indices of the X and Y points that are inside the polygon.
Based on discussions on the IDL newsgroup (comp.lang.idl-pvwave) and discussed here: http://www.idlcoyote.com/tips/point_in_polygon.html Primarily the work of B�rd Krane and William Connelly.
Written by: David W. Fanning, 4 September 2003. Vectorized the function in accord with William Connelly's suggestions 24 July 2005. DWF.