%% Centroid of Polygon
% Compute the centroids associated with a multiregion polygon.
%
% Create a polygon containing two solid regions, and then compute its centroid.

x1 = [0 1 2];
y1 = [0 1 0];
x2 = [2 3 4];
y2 = [1 2 1];
polyin = polyshape({x1,x2},{y1,y2});
[x,y] = centroid(polyin);
plot(polyin)
hold on
plot(x,y,'r*')
hold off

%
% To compute the centroid of each region separately, specify the boundary indices of each region in the second argument.

[x,y] = centroid(polyin,[1 2]);
plot(polyin)
hold on
plot(x(1),y(1),'r*',x(2),y(2),'r*')
hold off

%
% Alternatively, you can compute the centroid of each region by first separating the regions into separate polyshape objects. Use the regions function to create an array of polyshape objects, where each element of the array is a polyshape defining one of the triangular regions.

polyarray = regions(polyin)
[x,y] = centroid(polyarray)

% Copyright 2012 The MathWorks, Inc.