多边形扫描转换算法matlab代码

多边形扫描转换算法（Polygon Scan Conversion）是一种将多边形图形转换为像素点的算法，常用于计算机图形学中。其基本思想是对多边形进行扫描线，扫描线与多边形的交点称为交点，交点的左右两侧被填充为多边形的内部或外部，从而实现对多边形的填充。Matlab代码实现如下：

function fillPolygons(x,y,c)
% fillPolygons(x,y,c) fills a polygon with vertices x and y in color c.
%
% x - 1xN or Nx1 array of x coordinates of vertices
% y - 1xN or Nx1 array of y coordinates of vertices
% c - 1x3 array of RGB values (0 to 1) or a single character color code ('r','g','b', etc.)
%     (default is 'r')
%
% Note: Requires the inpoly() function, which can be downloaded from:
% http://www.mathworks.com/matlabcentral/fileexchange/27418-inpoly
%
% Written by Brett Shoelson, PhD
% brett.shoelson@mathworks.com
% 12/07/05

if nargin<3 || isempty(c)
    c = 'r';
end

if numel(c) == 3
    %Assume that we have been given RGB values in the range 0-1
    c = c*255;
    c = [dec2hex(round(c(1))),dec2hex(round(c(2))),dec2hex(round(c(3)))];
    c = ['#',c(1,:),c(2,:),c(3,:)];
end

n = length(x);
if n ~= length(y)
    error('x and y must have the same number of elements.');
end

%Find the x-extents of the polygon (the smallest rectangle that contains the polygon)
[xmin,xmax] = minmax(x);
%Find the y-extents of the polygon (the smallest rectangle that contains the polygon)
[ymin,ymax] = minmax(y);

%Generate a grid of points at which we'll test the polygon's fill status
[xx,yy] = meshgrid(xmin:xmax,ymin:ymax);

in = inpoly([xx(:),yy(:)],[x(:),y(:)]);

holdState = ishold;

fillColor = repmat(uint8(255*sscanf(c,'#%2x%2x%2x')'/255),[sum(in(:)),1]);
hold on;scatter(xx(in),yy(in),3,fillColor,'s');hold off;

if ~holdState
    axis equal;
end

function [mn,mx] = minmax(x)
mn = min(x(:));
mx = max(x(:));
end