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Add new 3D plotting function surfl. Add light functions diffuse and specular
author Kai Habel
date Thu, 08 Jan 2009 15:51:50 +0100
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children e4c9ecb64411
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8450
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1 ## Copyright (C) 2009 Kai Habel
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 3 of the License, or (at
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8 ## your option) any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, see
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17 ## <http://www.gnu.org/licenses/>.
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18
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19 ## -*- texinfo -*-
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20 ## @deftypefn {Function File} {} diffuse (@var{sx}, @var{sy}, @var{sz}, @var{l})
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21 ## Calculate diffuse reflection strength of a surface defined by the normal
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22 ## vector elements @var{sx}, @var{sy}, @var{sz}.
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23 ## The light vector can be specified using parameter @var{L}. It can be
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24 ## given as 2-element vector [azimuth, elevation] in degrees or as 3-element
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25 ## vector [lx, ly, lz].
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26 ## @seealso{specular, surfl}
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27 ## @end deftypefn
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28
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29 ## Author: Kai Habel <kai.habel@gmx.de>
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30
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31 function retval = diffuse (sx, sy, sz, lv)
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32
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33 ## general checks
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34 if (nargin != 4)
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35 usage ("number of arguments must be 4")
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36 endif
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37
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38 ## check for normal vector
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39 if (!size_equal (sx, sy, sz))
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40 usage ("SX, SY, and SZ must have same size")
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41 endif
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42
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43 ## check for light vector (lv) argument
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44 if (length (lv) < 2 || length (lv) > 3)
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45 usage ("light vector LV must be a 2- or 3-element vector");
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46 elseif (length (lv) == 2)
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47 [lv(1), lv(2), lv(3)] = sph2cart (lv(1) * pi/180, lv(2) * pi/180, 1.0);
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48 endif
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49
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50 ## normalize view and light vector
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51 if (sum (abs (lv)) > 0)
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52 lv /= norm (lv);
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53 endif
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54
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55 ns = sqrt (sx.^2 + sy.^2 + sz.^2);
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56 retval = (sx * lv(1) + sy * lv(2) + sz * lv(3)) ./ ns;
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57 retval(retval < 0) = 0;
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58
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59 endfunction