polyorient

Returns the orientation and signed area of a 2D polygon

Syntax:
[ORIENT,SAREA] = POLYORIENT(X,Y)

Inputs:
X, Y Vectors with the polygon vertices

Outputs:
ORIENT Polygon orientation. 1 if the orientation is counter-clockwise (direct), 0 otherwise
SAREA Signed area of the polygon, negative if orientation is not direct

Examples:
x1 = [0 0 1 1]; y1 = [1 2 2 1];
x2 = [0 0 1 1]; y2 = [1 0 0 1];
x3 = [x1 x2]; y3 = [y1 y2];

[o1,a1] = polyorient(x1,y1) % 0, -1
[o2,a2] = polyorient(x2,y2) % 1, 1
[o3,a3] = polyorient(x3,y3) % 0, 0