cutpolygon

CUTPOLYGON - Split a 2D polygon by a line, and remove one of the sides

Use CUTPOLYGON to cut alias intersect alias split alias slice a polygon P
(being a series of connected X,Y coordinates) with a line L (defined by
two points), removing a specified side s. L can serve as a bottom limit
('B'), top limit ('T'), left limit ('L'), or right limit ('R').

Syntax:
Pc = CUTPOLYGON(P, L, s, doSplit, doPlot, doTable)

Demo (cut random regular polygon with random line):
CUTPOLYGON demo

Inputs:
P Polygon coordinates [X, Y]
L Line defined by two coordinates [x1, y1; x2, y2]
s What side to remove, character or integer

Optional switches:
doSplit Add intermediate NaN entries if the polygon is split into non-connected parts (default false)
doPlot Plot original and cut polygon plus line (default false)
doTable Tabulate intersection and validity per polygon segment (default false)

Side options:
1 / B = bottom remove parts Y < intersection
2 / T = top remove parts Y > intersection
3 / L = left remove parts X < intersection
4 / R = right remove parts X > intersection

Finding the intersection:
http://en.wikipedia.org/wiki/Line-line_intersection

Output:
- Pc is the polygon post-cut [X, Y]
- Pc can be shorter than P (points are removed)
- Pc can contain intermediate NaN entries if doSplit is true

Version history (recent to ancient):
Jan 2010, Dominik Brands, fixed pure horizontal/vertical limit bug
Apr 2009, Jasper Menger , creation