[Octave-cvsupdate] SF.net SVN: octave:[10257] trunk/octave-forge/main/plot/inst/calc_shading.m

[<car...@us...>]

Revision: 10257
          http://octave.svn.sourceforge.net/octave/?rev=10257&view=rev
Author:   carandraug
Date:     2012-04-17 09:28:37 +0000 (Tue, 17 Apr 2012)
Log Message:
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calc_shading: new function submitted by Martin Helm <ma...@mh...>

Added Paths:
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    trunk/octave-forge/main/plot/inst/calc_shading.m

Added: trunk/octave-forge/main/plot/inst/calc_shading.m
===================================================================
--- trunk/octave-forge/main/plot/inst/calc_shading.m	                        (rev 0)
+++ trunk/octave-forge/main/plot/inst/calc_shading.m	2012-04-17 09:28:37 UTC (rev 10257)
@@ -0,0 +1,124 @@
+## Copyright (C) 2009-2012 Martin Helm <ma...@mh...>
+##
+## 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/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File}{[@var{cdata}] =} calc_shading (@var{amb}, @var{dif}, @var{spec}, @var{shine}, @var{colors}, @var{normals}, @var{lvec}, @var{vvec})
+## 
+##
+## If called with one output argument returns 
+## calculated color data for use with the patch function.
+##
+## @var{amb}, @var{dif}, @var{spec}, @var{shine} are the ambient, diffuse, 
+## specular and specular exponent properties for the lighting.
+##
+## @var{colors} can be a one or three column matrix with the same length
+## as the @var{normals} matrix of normal vectors.
+##
+## Alternatively a scalar or a RGB row vector can also be used for @var{colors}.
+## The object has then a single color.
+##
+## @var{lvec}: The light direction
+##
+## @var{vvec}: The view direction
+##
+## Type
+## @example
+## @group
+## demo calc_shading
+## @end group
+## @end example
+## to see how it works.
+##
+## Without using fltk it will also work but is very slow.
+##
+## @seealso{isocolors, isonormals}
+##
+## @end deftypefn
+
+## Author: Martin Helm <ma...@mh...>
+## Created: 2009-12-24
+## Credits: Kai Habel for his diffuse, specular and surfl functions
+
+function [ cdat ] = calc_shading (amb, dif, spec, shine, \
+                                 colors, normals, lvec, vvec)
+
+  lvec /= norm (lvec); # normalize light vector
+  vvec /= norm (vvec); # normalize view vector
+  ## normalize the normal vectors
+  normals = normals ./ repmat (sqrt (sumsq (normals, 2)), [1, 3]);
+  
+  ## if we have a single color, expand it
+  if rows (colors) == 1
+    colors = repmat (colors, [rows(normals), 1]);
+  endif
+
+  ## calculate the lighting
+
+  if columns (colors) == 1
+    ## if we have scalar colors do it the simple way
+    lfactor = amb * ones (rows (normals), 1) \
+        + dif * diffuse (normals(:, 1), normals(:, 2), normals(:, 3), lvec) \
+        + spec * specular (normals(:, 1), normals(:, 2), normals(:, 3), \
+                           lvec, vvec, shine);
+    cdat = colors .* lfactor;
+  else # we have rgb colors
+    ## ambient and diffuse like in the scalar case
+    lfactor = amb * ones (rows (normals), 1) \
+        + dif * diffuse (normals(:, 1), normals(:, 2), normals(:, 3), lvec);
+    lfactor = repmat (lfactor, [1, columns(colors)]);
+
+    ## we use a white specular light for a better effect
+    lf_spec = spec * specular (normals(:, 1), normals(:, 2), normals(:, 3), \
+                               lvec, vvec, shine); 
+    lf_spec = repmat (lf_spec, [1, columns(colors)]);
+
+    cdat = colors .* lfactor .+ lf_spec;
+  endif
+
+endfunction
+
+%!demo
+%! graphics_toolkit fltk
+%! clf
+%! fun = @(x, y, z) cos(x) .+ cos(y) .+ cos(z);
+%! points = linspace (-pi, pi, 51);
+%! [x, y, z] = meshgrid (points);
+%! f = fun (x, y, z);
+%! [F, v] = isosurface (x, y, z, f, 1.1); 
+%! vn = isonormals (x, y, z, f, v);
+%! cdat = calc_shading (0.3, 0.4, 0.8, 15.0, [1.0 .0 .0], vn, [-1.0; -0.5; -.8], [-.5; 1.5; -.1]);
+%! p = patch ("Faces", F, "Vertices", v, "FaceVertexCData", cdat, "FaceColor", "interp", "EdgeColor", "none"); 
+%! view(30,30) 
+%! grid on;
+%! title(['Demo shading in red, Contour Value = ',num2str(1.1)]);
+%! xlabel('X');ylabel('Y');zlabel('Z');
+%! axis ([-pi, pi, -pi, pi, -pi, pi]);
+
+%!demo
+%! clf
+%! fun = @(x, y, z) cos(x) .+ cos(y) .+ cos(z);
+%! points = linspace (-pi, pi, 51);
+%! [x, y, z] = meshgrid (points);
+%! f = fun (x, y, z);
+%! [F, v] = isosurface (x, y, z, f, 1.1); 
+%! vn = isonormals (x, y, z, f, v);
+%! c = isocolors (x, y, z, rand(size(x)),  rand(size(x)), rand(size(x)), v);
+%! cdat = calc_shading (0.5, 0.4, 0.8, 10.0, c, vn, [-1.0; -0.5; -.8], [-.5; 1.5; -.1]);
+%! p = patch ("Faces", F, "Vertices", v, "FaceVertexCData", cdat, "FaceColor", "interp", "EdgeColor", "none"); 
+%! view(45,30) 
+%! grid on;
+%! title(['Demo shading, random colored, Contour Value = ',num2str(1.1)]);
+%! xlabel('X');ylabel('Y');zlabel('Z');
+%! axis ([-pi, pi, -pi, pi, -pi, pi]);

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