Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / vrml-1.0.13 / checker_color.m

diff --git a/octave_packages/vrml-1.0.13/checker_color.m b/octave_packages/vrml-1.0.13/checker_color.m
new file mode 100644 (file)
index 0000000..8d80bc2
--- /dev/null
+++ b/octave_packages/vrml-1.0.13/checker_color.m
@@ -0,0 +1,41 @@
+## Copyright (C) 2010-2012 Etienne Grossmann <etienne@egdn.net>
+##
+## This program 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.
+##
+## This program 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
+## this program; if not, see <http://www.gnu.org/licenses/>.
+
+## col = checker_color (R,C, checker, col)
+
+function col = checker_color (checker, col, R,C)
+
+if length (checker) == 1, checker = [checker, checker]; end
+
+if checker(1) > 0, checker(1) = - (C-1)/checker(1); end
+if checker(2) > 0, checker(2) = - (R-1)/checker(2); end
+
+checker *= -1;
+
+colx = 2 * (rem (0:C-2,2*checker(1)) < checker(1)) - 1;
+coly = 2 * (rem (0:R-2,2*checker(2)) < checker(2)) - 1;
+icol = 1 + ((coly'*colx) > 0);
+                               # Keep at most 1st 2 colors of col for the
+                               # checker
+if prod (size (col)) == 2,
+  col = [1;1;1]*col;
+elseif  prod (size (col)) < 6, # Can't be < 3 because of previous code
+  col = col(1:3)(:);
+  if all (col >= 1-eps), col = [col [0;0;0]];  # Black and White
+  else                   col = [col [1;1;1]];  # X and White
+  end
+end
+col = reshape (col(:),3,2);
+col = col(:,icol);