Mercurial > hg > octave-nkf
annotate scripts/plot/draw/shrinkfaces.m @ 18402:6165053c56b3
shrinkfaces.m: Overhaul function.
* shrinkfaces.m: Improve docstring. Add %!tests for input validation.
| author | Rik <rik@octave.org> |
|---|---|
| date | Wed, 22 Jan 2014 17:20:40 -0800 |
| parents | d63878346099 |
| children | d3a223128efc |
| rev | line source |
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1 ## Copyright (C) 2012-2013 Martin Helm |
| 14574 | 2 ## |
| 3 ## This file is part of Octave. | |
| 4 ## | |
| 5 ## Octave is free software; you can redistribute it and/or modify it | |
| 6 ## under the terms of the GNU General Public License as published by | |
| 7 ## the Free Software Foundation; either version 3 of the License, or (at | |
| 8 ## your option) any later version. | |
| 9 ## | |
| 10 ## Octave is distributed in the hope that it will be useful, but | |
| 11 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 ## General Public License for more details. | |
| 14 ## | |
| 15 ## You should have received a copy of the GNU General Public License | |
| 16 ## along with Octave; see the file COPYING. If not, see | |
| 17 ## <http://www.gnu.org/licenses/>. | |
| 18 | |
| 19 ## -*- texinfo -*- | |
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20 ## @deftypefn {Function File} {} shrinkfaces (@var{p}, @var{sf}) |
| 14574 | 21 ## @deftypefnx {Function File} {@var{nfv} =} shrinkfaces (@var{p}, @var{sf}) |
| 22 ## @deftypefnx {Function File} {@var{nfv} =} shrinkfaces (@var{fv}, @var{sf}) | |
| 23 ## @deftypefnx {Function File} {@var{nfv} =} shrinkfaces (@var{f}, @var{v}, @var{sf}) | |
| 24 ## @deftypefnx {Function File} {[@var{nf}, @var{nv}] =} shrinkfaces (@dots{}) | |
| 25 ## | |
| 18402 | 26 ## Reduce the size of faces in a patch by the shrink factor @var{sf}. |
| 27 ## | |
| 28 ## The patch object can be specified by a graphics handle (@var{p}), a patch | |
| 29 ## structure (@var{fv}) with the fields @qcode{"faces"} and @qcode{"vertices"}, | |
| 30 ## or as two separate matrices (@var{f}, @var{v}) of faces and vertices. | |
| 14574 | 31 ## |
| 18402 | 32 ## The shrink factor @var{sf} is a positive number specifying the percentage |
| 33 ## of the original area the new face will occupy. If no factor is given the | |
| 34 ## default is 0.3 (a reduction to 30% of the original size). A factor greater | |
| 35 ## than 1.0 will result in the expansion of faces. | |
| 36 ## | |
| 37 ## Given a patch handle as the first input argument and no output parameters, | |
| 38 ## perform the shrinking of the patch faces in place and redraw the patch. | |
| 14574 | 39 ## |
| 40 ## If called with one output argument, return a structure with fields | |
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41 ## @qcode{"faces"}, @qcode{"vertices"}, and @qcode{"facevertexcdata"} |
| 18402 | 42 ## containing the data after shrinking. This structure can be used directly |
| 43 ## as an input argument to the @code{patch} function. | |
| 14574 | 44 ## |
| 18402 | 45 ## @strong{Caution:}: Performing the shrink operation on faces which are not |
| 46 ## convex can lead to undesirable results. | |
| 14574 | 47 ## |
| 18402 | 48 ## Example: a triangulated 3/4 circle and the corresponding shrunken version. |
| 14574 | 49 ## |
| 50 ## @example | |
| 51 ## @group | |
| 52 ## [phi r] = meshgrid (linspace (0, 1.5*pi, 16), linspace (1, 2, 4)); | |
| 53 ## tri = delaunay (phi(:), r(:)); | |
| 54 ## v = [r(:).*sin(phi(:)) r(:).*cos(phi(:))]; | |
| 55 ## clf () | |
| 56 ## p = patch ("Faces", tri, "Vertices", v, "FaceColor", "none"); | |
| 57 ## fv = shrinkfaces (p); | |
| 58 ## patch (fv) | |
| 59 ## axis equal | |
| 60 ## grid on | |
| 61 ## @end group | |
| 62 ## @end example | |
| 63 ## | |
| 64 ## @seealso{patch} | |
| 65 ## @end deftypefn | |
| 66 | |
| 67 ## Author: Martin Helm <martin@mhelm.de> | |
| 68 | |
| 69 function [nf, nv] = shrinkfaces (varargin) | |
| 70 | |
| 71 if (nargin < 1 || nargin > 3 || nargout > 2) | |
| 72 print_usage (); | |
| 73 endif | |
| 74 | |
| 75 sf = 0.3; | |
| 18402 | 76 colors = []; |
| 14574 | 77 p = varargin{1}; |
| 78 | |
| 79 if (ishandle (p) && nargin < 3) | |
| 80 faces = get (p, "Faces"); | |
| 81 vertices = get (p, "Vertices"); | |
| 82 colors = get (p, "FaceVertexCData"); | |
| 83 if (nargin == 2) | |
| 84 sf = varargin{2}; | |
| 85 endif | |
| 86 elseif (isstruct (p) && nargin < 3) | |
| 87 faces = p.faces; | |
| 88 vertices = p.vertices; | |
| 89 if (isfield (p, "facevertexcdata")) | |
| 90 colors = p.facevertexcdata; | |
| 91 endif | |
| 92 if (nargin == 2) | |
| 93 sf = varargin{2}; | |
| 94 endif | |
| 95 elseif (ismatrix (p) && nargin >= 2 && ismatrix (varargin{2})) | |
| 96 faces = p; | |
| 97 vertices = varargin{2}; | |
| 98 if (nargin == 3) | |
| 99 sf = varargin{3}; | |
| 100 endif | |
| 101 else | |
| 102 print_usage (); | |
| 103 endif | |
| 104 | |
| 105 if (! isscalar (sf) || sf <= 0) | |
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106 error ("shrinkfaces: scale factor must be a positive scalar"); |
| 14574 | 107 endif |
| 108 | |
| 18402 | 109 nc = columns (vertices); |
| 110 if (nc < 2 || nc > 3) | |
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111 error ("shrinkfaces: only 2-D and 3-D patches are supported"); |
| 14574 | 112 endif |
| 113 | |
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114 m = columns (faces); |
| 14574 | 115 if (m < 3) |
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116 error ("shrinkfaces: faces must consist of at least 3 vertices"); |
| 14574 | 117 endif |
| 118 | |
| 119 v = vertices(faces'(:), :); | |
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120 if (isempty (colors) || rows (colors) == rows (faces)) |
| 14574 | 121 c = colors; |
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122 elseif (rows (colors) == rows (vertices)) |
| 14574 | 123 c = colors(faces'(:), :); |
| 124 else | |
| 18402 | 125 c = []; # Discard inconsistent color data. |
| 14574 | 126 endif |
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127 sv = rows (v); |
| 18402 | 128 ## We have to deal with a possibly very large number of vertices, so use |
| 129 ## sparse as midpoint (1/m, ..., 1/m) in generalized barycentric coordinates. | |
| 130 midpoints = full (kron (speye (sv / m), ones (m, m) / m) * sparse (v)); | |
| 14574 | 131 v = sqrt (sf) * (v - midpoints) + midpoints; |
| 132 f = reshape (1:sv, m, sv / m)'; | |
| 133 | |
| 134 switch (nargout) | |
| 135 case 0 | |
| 136 if (ishandle (p)) | |
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137 ## avoid exceptions |
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138 set (p, "FaceVertexCData", [], "CData", []); |
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139 set (p, "Vertices", v, "Faces", f, "FaceVertexCData", c); |
| 14574 | 140 else |
| 141 nf = struct ("faces", f, "vertices", v, "facevertexcdata", c); | |
| 142 endif | |
| 143 case 1 | |
| 144 nf = struct ("faces", f, "vertices", v, "facevertexcdata", c); | |
| 145 case 2 | |
| 146 nf = f; | |
| 147 nv = v; | |
| 148 endswitch | |
| 149 | |
| 150 endfunction | |
| 151 | |
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152 |
| 14574 | 153 %!demo |
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154 %! clf; |
| 14574 | 155 %! faces = [1 2 3; 1 3 4]; |
| 156 %! vertices = [0 0; 1 0; 1 1; 0 1]; | |
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157 %! patch ('Faces', faces, 'Vertices', vertices, 'FaceColor', 'none'); |
| 14574 | 158 %! fv = shrinkfaces (faces, vertices, 0.25); |
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159 %! patch (fv); |
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160 %! axis equal; |
| 14574 | 161 |
| 162 %!demo | |
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163 %! clf; |
| 14574 | 164 %! faces = [1 2 3 4; 5 6 7 8]; |
| 165 %! vertices = [0 0; 1 0; 2 1; 1 1; 2 0; 3 0; 4 1; 3.5 1]; | |
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166 %! patch ('Faces', faces, 'Vertices', vertices, 'FaceColor', 'none'); |
| 14574 | 167 %! fv = shrinkfaces (faces, vertices, 0.25); |
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168 %! patch (fv); |
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169 %! axis equal; |
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170 %! grid on; |
| 14574 | 171 |
| 172 %!demo | |
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173 %! clf; |
| 14574 | 174 %! faces = [1 2 3 4]; |
| 175 %! vertices = [-1 2; 0 0; 1 2; 0 1]; | |
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176 %! patch ('Faces', faces, 'Vertices', vertices, 'FaceColor', 'none'); |
| 14574 | 177 %! fv = shrinkfaces (faces, vertices, 0.25); |
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178 %! patch (fv); |
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179 %! axis equal; |
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180 %! grid on; |
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181 %! title 'faces which are not convex are clearly not allowed' |
| 14574 | 182 |
| 183 %!demo | |
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184 %! clf; |
| 14574 | 185 %! [phi r] = meshgrid (linspace (0, 1.5*pi, 16), linspace (1, 2, 4)); |
| 186 %! tri = delaunay (phi(:), r(:)); | |
| 187 %! v = [r(:).*sin(phi(:)) r(:).*cos(phi(:))]; | |
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188 %! p = patch ('Faces', tri, 'Vertices', v, 'FaceColor', 'none'); |
| 14574 | 189 %! fv = shrinkfaces (p); |
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190 %! patch (fv); |
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191 %! axis equal; |
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192 %! grid on; |
| 14574 | 193 |
| 194 %!demo | |
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195 %! clf; |
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196 %! N = 10; % N intervals per axis |
| 14574 | 197 %! [x, y, z] = meshgrid (linspace (-4,4,N+1)); |
| 198 %! val = x.^3 + y.^3 + z.^3; | |
| 199 %! fv = isosurface (x, y, z, val, 3, z); | |
| 200 %! | |
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201 %! p = patch ('Faces', fv.faces, 'Vertices', fv.vertices, 'FaceVertexCData', ... |
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202 %! fv.facevertexcdata, 'FaceColor', 'interp', 'EdgeColor', 'black'); |
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203 %! axis equal; |
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204 %! view (115, 30); |
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205 %! drawnow; |
| 14574 | 206 %! shrinkfaces (p, 0.6); |
| 207 | |
| 208 %!shared faces, vertices, nfv, nfv2 | |
| 209 %! faces = [1 2 3]; | |
| 210 %! vertices = [0 0 0; 1 0 0; 1 1 0]; | |
| 211 %! nfv = shrinkfaces (faces, vertices, 0.7); | |
| 212 %! nfv2 = shrinkfaces (nfv, 1/0.7); | |
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213 %!assert (isfield (nfv, "faces")) |
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214 %!assert (isfield (nfv, "vertices")) |
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215 %!assert (size (nfv.faces), [1 3]) |
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216 %!assert (size (nfv.vertices), [3 3]) |
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217 %!assert (norm (nfv2.vertices - vertices), 0, 2*eps) |
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218 |
| 18402 | 219 %% Test input validation |
| 220 %!error shrinkfaces () | |
| 221 %!error shrinkfaces (1,2,3,4) | |
| 222 %!error [a,b,c] = shrinkfaces (1) | |
| 223 %!error <scale factor must be a positive scalar> shrinkfaces (nfv, ones (2)) | |
| 224 %!error <scale factor must be a positive scalar> shrinkfaces (nfv, 0) | |
| 225 %!error <only 2-D and 3-D patches are supported> shrinkfaces (faces, ones (3,1)) | |
| 226 %!error <only 2-D and 3-D patches are supported> shrinkfaces (faces, ones (3,4)) | |
| 227 %!error <faces must consist of at least 3 vertices> shrinkfaces (faces(1:2), vertices) | |
| 228 |