From 9a750e78e10642fb3cb009ef049cfbbd39131bf7 Mon Sep 17 00:00:00 2001
From: dlegland <david.legland@nantes.inra.fr>
Date: Fri, 11 Mar 2016 20:05:45 +0100
Subject: [PATCH] polygons2d/polygonSignature.m: returns NaN for
 non-intersecting edges

---
 matGeom/polygons2d/polygonSignature.m | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/matGeom/polygons2d/polygonSignature.m b/matGeom/polygons2d/polygonSignature.m
index 63f311ca..179b0386 100644
--- a/matGeom/polygons2d/polygonSignature.m
+++ b/matGeom/polygons2d/polygonSignature.m
@@ -3,10 +3,12 @@
 %
 %   DISTS = polygonSignature(POLY, THETALIST)
 %   Computes the polar signature of a polygon, for a set of angles in
-%   degrees.
+%   degrees. If a ray at a given angle does not intersect the polygon, the
+%   corresponding distance value is set to NaN.
 %
 %   DISTS = polygonSignature(POLY, N)
-%   When N is a scalar, uses N angles equally distributed between 0 and 360.
+%   When N is a scalar, uses N angles equally distributed between 0 and 360
+%   degrees.
 %   
 %   [DISTS, THETA] = polygonSignature(...)
 %   Also returns the angle set for which the signature was computed.
@@ -15,7 +17,7 @@
 %   polygonSignature
 %
 %   See also
-%     polygons2d, signatureToPolygon
+%     polygons2d, signatureToPolygon, intersectRayPolygon
 %
 
 % ------
@@ -46,7 +48,7 @@
 
 % allocate memory
 nTheta = length(thetaList);
-res = zeros(nTheta, 1);
+res = NaN * ones(nTheta, 1);
 
 % iterate on angles
 for i = 1:length(thetaList)
@@ -54,5 +56,7 @@
     ray = [center cos(theta) sin(theta)];
 
     ptInt = intersectRayPolygon(ray, poly);
-    res(i) = distancePoints(center, ptInt(1,:));
+    if ~isempty(ptInt)
+        res(i) = distancePoints(center, ptInt(1,:));
+    end
 end