Mercurial > forge
view main/geometry/inst/shape2d/shapecentroid.m @ 9820:e65110da131a octave-forge
geometry: Fixed bugs detected by Rafael (dev packager). Improved docstring of cbezier2poly. Verified all other shape2d functions. Moved test form shapetransfrom to shapecentriod
author | jpicarbajal |
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date | Thu, 22 Mar 2012 22:05:06 +0000 |
parents | 9e0034f84724 |
children | 648d10dd8b02 |
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%% Copyright (c) 2011 Juan Pablo Carbajal <carbajal@ifi.uzh.ch> %% %% 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{cm} =} shapecentroid (@var{pp}) %% Centroid of a simple plane shape defined with piecewise smooth polynomials. %% %% The shape is defined with piecewise smooth polynomials. @var{pp} is a %% cell where each elements is a 2-by-(poly_degree+1) matrix containing a pair %% of polynomials. %% @code{px(i,:) = pp@{i@}(1,:)} and @code{py(i,:) = pp@{i@}(2,:)}. %% %% The edges of the shape should not self-intersect. This function does not check for the %% sanity of the shape. %% %% @seealso{shapearea, shape2polygon} %% @end deftypefn function cm = shapecentroid (shape) cm = sum( cell2mat ( cellfun (@CMint, shape, 'UniformOutput', false)), 1); A = shapearea(shape); cm = cm / A; [~,id] = lastwarn ('',''); if strcmp (id ,'geom2d:shapearea:InvalidResult') lastwarn('Inverting centriod','geom2d:shapecentriod:InvalidResult'); cm = -cm; end endfunction function dcm = CMint (x) px = x(1,:); py = x(2,:); Px = polyint (conv(conv (-px , py) , polyder (px))); Py = polyint (conv(conv (px , py) , polyder (py))); dcm = zeros (1,2); dcm(1) = diff(polyval(Px,[0 1])); dcm(2) = diff(polyval(Py,[0 1])); endfunction %!demo % non-convex bezier shape %! boomerang = {[ 0 -2 1; ... %! -4 4 0]; ... %! [0.25 -1; ... %! 0 0]; ... %! [ 0 1.5 -0.75; ... %! -3 3 0]; %! [0.25 0.75; ... %! 0 0]}; %! CoM = shapecentroid (boomerang) %! Gcentriod = centroid(shape2polygon(boomerang)) %! %! figure(1); clf; %! shapeplot(boomerang,10,'-o'); %! hold on %! drawPoint(CoM,'xk;shape centriod;'); %! drawPoint(Gcentriod,'xr;point centriod;'); %! hold off %! axis equal %!demo %! Lshape = {[0.00000 0.76635; -0.67579 -0.24067]; ... %! [0.77976 0.76635; 0.00000 -0.91646]; ... %! [0.00000 1.54611; 0.38614 -0.91646]; ... %! [-0.43813 1.54611; 0.00000 -0.53032]; ... %! [0.00000 1.10798; 0.28965 -0.53032]; ... %! [-0.34163 1.10798; 0.00000 -0.24067]};... %! CoM = shapecentroid (Lshape) %! Gcentriod = centroid (shape2polygon (Lshape)) %! %! shapeplot(Lshape,10,'-o'); %! hold on %! drawPoint(CoM,'xk;shape centriod;'); %! drawPoint(Gcentriod,'xr;point centriod;'); %! hold off %! axis equal %!test %! square = {[1 -0.5; 0 -0.5]; [0 0.5; 1 -0.5]; [-1 0.5; 0 0.5]; [0 -0.5; -1 0.5]}; %! CoM = shapecentroid (square); %! assert (CoM, [0 0], sqrt(eps)); %!test %! square = {[1 -0.5; 0 -0.5]; [0 0.5; 1 -0.5]; [-1 0.5; 0 0.5]; [0 -0.5; -1 0.5]}; %! square_t = shapetransform (square,[1;1]); %! CoM = shapecentroid (square_t); %! assert (CoM, [1 1], sqrt(eps)); %!test %! circle = {[1.715729 -6.715729 0 5; ... %! -1.715729 -1.568542 8.284271 0]; ... %! [1.715729 1.568542 -8.284271 0; ... %! 1.715729 -6.715729 0 5]; ... %! [-1.715729 6.715729 0 -5; ... %! 1.715729 1.568542 -8.284271 0]; ... %! [-1.715729 -1.568542 8.284271 0; ... %! -1.715729 6.715729 0 -5]}; %! CoM = shapecentroid (circle); %! assert (CoM , [0 0], 5e-3); %!shared shape %! shape = {[-93.172 606.368 -476.054 291.429; ... %! -431.196 637.253 11.085 163.791]; ... %! [-75.3626 -253.2337 457.1678 328.5714; ... %! 438.7659 -653.6278 -7.9953 380.9336]; ... %! [-89.5841 344.9716 -275.3876 457.1429; ... %! -170.3613 237.8858 1.0469 158.0765];... %! [32.900 -298.704 145.804 437.143; ... %! -243.903 369.597 -34.265 226.648]; ... %! [-99.081 409.127 -352.903 317.143; ... %! 55.289 -114.223 -26.781 318.076]; ... %! [-342.231 191.266 168.108 274.286; ... %! 58.870 -38.083 -89.358 232.362]}; %!test % x-Reflection %! v = shapecentroid (shape)(:); %! T = createLineReflection([0 0 1 0]); %! nshape = shapetransform (shape, T); %! vn = shapecentroid (nshape)(:); %! assert(vn,T(1:2,1:2)*v); %!test % Rotation %! v = shapecentroid (shape)(:); %! T = createRotation(v.',pi/2); %! nshape = shapetransform (shape, T); %! vn = shapecentroid (nshape)(:); %! assert(vn,v,1e-2); %!test % Translation %! v = shapecentroid (shape)(:); %! nshape = shapetransform (shape, -v); %! vn = shapecentroid (nshape)(:); %! assert(vn,[0; 0],1e-2);