1 files changed, 86 insertions, 0 deletions
diff --git a/inst/isIntersectionInPolygon3D.m b/inst/isIntersectionInPolygon3D.m
new file mode 100644
index 0000000..e2b61ca
--- /dev/null
+++ b/inst/isIntersectionInPolygon3D.m
@@ -0,0 +1,86 @@
+## Copyright (C) 2014 Andreas Emch and Eduardo Hahn Paredes
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+% -*- texinfo -*-
+% @deftypefn {Function File} {[@var{in}, @var{distance}] =} isIntersectionInPolygon3D (@var{p1}, @var{p2}, @var{a}, @var{b}, @var{c})
+% For a line, defined by two vector-points @code{(@var{p1}, @var{p2})},
+% calculate the intersection-point with the plane, defined by three vector-points @code{(@var{a}, @var{b}), @var{c})},
+% and determine if this intersection-point is inside or on the polygon defined by three vector-points @code{(@var{a}, @var{b}), @var{c})}
+% The variables @var{p1}, @var{p2}, @var{a}, @var{b}, @var{c} are all points in the 3D-dimension.
+% @seealso{inpolygon}
+% @end deftypefn
+
+% Author: Andreas Emch, Eduardo Hahn Paredes
+% Created: January 2013
+
+function [in distance point] = isIntersectionInPolygon3D (p1, p2, a, b, c)
+    u = b-a;
+    v = c-a;
+
+    E = [a u v];
+    n = cross(u',v');
+    
+    if (u == v)
+        in = false;
+        distance = NaN;
+        point = NaN;
+        return;
+    endif
+    
+    x = n(1,1);
+    y = n(1,2);
+    z = n(1,3);
+    d = -(a(1,1) * x + a(2,1) * y + a(3,1) * z);
+    
+    plane = 0;
+    
+    if (E(1,2) == 0 && E(1,3) == 0)
+        plane = 1;
+    elseif (E(2,2) == 0 && E(2,3) == 0)
+        plane = 2;
+    elseif (E(3,2) == 0 && E(3,3) == 0)
+        plane = 3;
+    else
+        plane = 0;
+    endif
+    
+    P = [p1 p2-p1];
+    t = -(x * P(1,1) + y * P(2,1) + z * P(3,1) + d) / (x * P(1,2) + y * P(2,2) + z * P(3,2));
+
+    dP = p1 + (t .* (p2-p1));
+    xPoly = [a(1,1) b(1,1) c(1,1) a(1,1)];
+    yPoly = [a(2,1) b(2,1) c(2,1) a(2,1)];
+    zPoly = [a(3,1) b(3,1) c(3,1) a(3,1)];    
+
+    [in1 on1] = inpolygon(dP(1,1), dP(2,1), xPoly, yPoly);
+    [in2 on2] = inpolygon(dP(2,1), dP(3,1), yPoly, zPoly);
+    [in3 on3] = inpolygon(dP(3,1), dP(1,1), zPoly, xPoly);
+    
+    if ((plane == 0 && (in1 == 1 || on1 == 1) && (in2 == 1 || on2 == 1) && (in3 == 1 || on3 == 1))
+        ||(plane == 1 && (in2 == 1 || on2 == 1))
+        ||(plane == 2 && (in3 == 1 || on3 == 1))
+        ||(plane == 3 && (in1 == 1 || on1 == 1)))
+        in = true;
+        distance = t;
+        point = dP;
+    else
+        in = false;
+        distance = NaN;
+        point = dP;
+    endif
+endfunction