function d = dpoly ( p, pv ) %*****************************************************************************80 % %% DPOLY returns the signed distance of one or more points to a polygon. % % Discussion: % % The polygon is described as a sequence of vertices. In order for % a proper calculation, it is necessary that the first vertex be % repeated as the last vertex. Thus, if your polygon is a square, % you will be specifying FIVE vertices. % % Licensing: % % (C) 2004 Per-Olof Persson. % See COPYRIGHT.TXT for details. % % Modified: % % 11 March 2006 % % Reference: % % Per-Olof Persson and Gilbert Strang, % A Simple Mesh Generator in MATLAB, % SIAM Review, % Volume 46, Number 2, June 2004, pages 329-345. % % Parameters: % % Input, real P(NP,2), the coordinates of a set of nodes. % % Input, real PV(NVS,2), the coordinates of the vertices of the polygon. % % Output, real D, the signed distance of each point to the polygon, % which is negative, 0, or positive depending on whether the point % is inside, on, or outside the polygon. % np = size ( p, 1 ); nvs = size ( pv, 1 ) - 1; % % DSEGMENT computes the (unsigned) distance from each point P to every line segment % that makes up the polygon. % ds = dsegment ( p, pv ); %ds=zeros(np,nvs); %for iv=1:nvs % ds(:,iv)=donesegment(p,pv(iv:iv+1,:)); %end d = min ( ds, [], 2 ); % % INPOLYGON is a built-in MATLAB routine, which allows us to determine the % sign of the signed distance function. % d = (-1) .^ ( inpolygon ( p(:,1), p(:,2), pv(:,1), pv(:,2) ) ) .* d; % MEXED %function ds=donesegment(p,pv) % %e=ones(size(p,1),1); % %v=diff(pv,1); %w=p-e*pv(1,:); % %c1=sum(w.*v(e,:),2); %c2=sum(v(e,:).^2,2); % %ds=0*e; % %ix=c1<=0; %ds(ix)=sqrt(sum((p(ix,:)-pv(1*ones(sum(ix),1),:)).^2,2)); % %ix=c1>=c2; %ds(ix)=sqrt(sum((p(ix,:)-pv(2*ones(sum(ix),1),:)).^2,2)); % %ix=c1>0 & c2>c1; %nix=sum(ix); %if nix>0 % Pb=ones(nix,1)*pv(1,:)+c1(ix)./c2(ix)*v; % ds(ix)=sqrt(sum((p(ix,:)-Pb).^2,2)); %end return end