gm_cpoly.m

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function b = gm_cpoly(verts, codes)
% GM_CPOLY: Construct a 2D brep given boundary paths.
% Matlab:   newbrep = gm_cpoly(vtxlist, codelist)
% This routine creates a 2D polygon.  The argument vtxlist is a matrix
% of vertices.  Each row has two entries that are vertex coordinates.
% These are the vertices of the polygon in order.  The codelist is a
% list of codes; there is one code per vertex.  The codes are as
% follows:
%  0 = vertex is start of a new loop
%  1 = vertex is start of a new toplogical edge; part of existing loop
%  2 = vertex is start of bezier curve; part of existing topological edge
%  3 = vertex is an intermediate bezier control point.
% The first entry in codes must be 0.  An interactive graphical
% front-end to this routine is provided by gmmouse.

global gm_brep_type_code
[numv,n] = size(verts);
if n ~= 2
  error('verts argument wrong size');
end
if numv < 3
  error('Need at least three vertices for gm_cpoly.')
end

[numv2,n2] = size(codes);

if n2 ~= 1
  error('Second argument to gm_cpoly must be a column vector')
end

if numv2 ~= numv
  error('Two arguments to gm_cpoly must have the same number of entries')
end

if codes(1) ~= 0
  error "first entry of nodetypelist must be 0"
end

if any(codes < 0) | any(codes > 3)
  error('each entry of codes must be an integer in 0..3')
end
    
%A code to close the final loop.

verts = [verts; [-1e308 -1e308]];

codes = [codes; -1];

cplist = [];
tvert = [];
tedge = {};
rbdry = {};
thisedgecurves = {};
thiscurve = [];
vert_to_seq = zeros(numv + 1, 1);
seq_to_vert = zba(zeros(numv + 1, 1));
edge_to_seq = zeros(numv + 1, 1);
seq_to_edge = zba(zeros(numv + 1, 1));
vcount = 0;
ecount = 0;
loopstart = 1;

for cpind = 1 : numv + 1
  vert = verts(cpind, :);
  code = codes(cpind);
  if code < 2 & code > -1
    tvert{1,vcount+1} = sprintf('v%d', cpind);
    tvert{2,vcount+1} = {};
    tvert{3,vcount+1} = {};
    tvert{4,vcount+1} = {};
    tvert{5,vcount+1} = {'vertex'; []; [cpind - 1]};
    seq_to_vert(vcount) = cpind;
    vert_to_seq(cpind) = vcount;
    vcount = vcount + 1;
  end

  if code < 3 & cpind > 1
    if code <= 0 
      fvertex = loopstart;
    else	
      fvertex = cpind;
    end
    thiscurve  = [thiscurve; fvertex-1];
    degree  = length(thiscurve) - 1;
    bez1 = {'bezier_curve'; [degree]; thiscurve'};
    [scrap,sz1] = size(thisedgecurves);
    thisedgecurves{1,sz1+1} = 'bezier_curve';
    thisedgecurves{2,sz1+1} = [degree];
    thisedgecurves{3,sz1+1} = thiscurve';
    thiscurve = [];
    if code < 2
      [scrap,nume] = size(tedge);
      tedge{1,ecount+1} = sprintf('e%d', cpind);
      tedge{2,ecount+1} = {};
      tedge{3,ecount+1} = ...
	{sprintf('v%d', edgestart), sprintf('v%d', fvertex)};	
      tedge{4,ecount+1} = {};
      tedge{5,ecount+1} = thisedgecurves;	
      seq_to_edge(ecount) = cpind;
      edge_to_seq(cpind) = ecount;
      rbdry{ecount+1} = sprintf('e%d', cpind);
      ecount = ecount + 1;
      thisedgecurves = {};
    end
  end
  if code == -1
    break;
  end
  cplist = [cplist,vert'];
  thiscurve = [thiscurve;cpind-1];
  if code < 2
    edgestart = cpind;
    if code < 1
      loopstart = cpind;
    end    
  end
end

global GM_BREP_TYPE_CODE
tregion = {'mregion'; {}; rbdry; {}; {}};
b = zba({GM_BREP_TYPE_CODE; 2; 2; {}; cplist; tvert; tedge; tregion});

% ------------------------------------------------------------------
% Copyright (c) 1999 by Cornell University.  All rights reserved
% See the accompanying file 'Copyright' for authorship information,
% the terms of the license governing this software, and disclaimers
% concerning this software.
% ------------------------------------------------------------------
% This file is part of the QMG software.  
% Version 2.0 of QMG, release date September 3, 1999
% ------------------------------------------------------------------