## Contents

- Base polygon
- Positive expansion
- Negative expansion

    %DEMOEXPANDPOLYGON  Expand a polygon by a given distance
    %   demoExpandPolygon
    %
    %   Example
    %   demoExpandPolygon
    %
    %   See also
    %
    %
    % ------
    % Author: David Legland
    % e-mail: david.legland@grignon.inra.fr
    % Created: 2009-06-17,    using Matlab 7.7.0.471 (R2008b)
    % Copyright 2009 INRA - Cepia Software Platform.

## Base polygon

    % create a non-convex polygon
    poly = [200 100;200 150;150 150;150 200;50 200;150 100];

    % show the polygon
    figure(1); clf; hold on;
    drawPolygon(poly, 'linewidth', 2);

    % set up display
    axis equal;
    axis([20 230 70 230]);

## Positive expansion

    % expand the polygon by a positive distance (outside of the polygon)
    polyOut = expandPolygon(poly, 10);

    % draw the expanded polygon
    drawPolygon(polyOut, 'k');

## Negative expansion

    % expand the polygon by a negative distance (inside the polygon)
    polyIn = expandPolygon(poly, -20, 'cleanuploops', true);

    % draw the expanded polygon
    drawPolygon(polyIn, 'g');

    % decorate
    legend('Original', 'Outside', 'Inside')