--- /dev/null
+function srf = nrbcoons(u1, u2, v1, v2)
+%
+% NRBCOONS: Construction of a Coons patch.
+%
+% Calling Sequence:
+%
+% srf = nrbcoons(ucrv1, ucrv2, vcrv1, vcrv2)
+%
+% INPUT:
+%
+% ucrv1 : NURBS curve defining the bottom U direction boundary of
+% the constructed NURBS surface.
+%
+% ucrv2 : NURBS curve defining the top U direction boundary of
+% the constructed NURBS surface.
+%
+% vcrv1 : NURBS curve defining the bottom V direction boundary of
+% the constructed NURBS surface.
+%
+% vcrv2 : NURBS curve defining the top V direction boundary of
+% the constructed NURBS surface.
+%
+% OUTPUT:
+%
+% srf : Coons NURBS surface patch.
+%
+% Description:
+%
+% Construction of a bilinearly blended Coons surface patch from four NURBS
+% curves that define the boundary.
+%
+% The orientation of the four NURBS boundary curves.
+%
+% ^ V direction
+% |
+% | ucrv2
+% ------->--------
+% | |
+% | |
+% vcrv1 ^ Surface ^ vcrv2
+% | |
+% | |
+% ------->-----------> U direction
+% ucrv1
+%
+%
+% Examples:
+%
+% // Define four NURBS curves and construct a Coons surface patch.
+% pnts = [ 0.0 3.0 4.5 6.5 8.0 10.0;
+% 0.0 0.0 0.0 0.0 0.0 0.0;
+% 2.0 2.0 7.0 4.0 7.0 9.0];
+% crv1 = nrbmak(pnts, [0 0 0 1/3 0.5 2/3 1 1 1]);
+%
+% pnts= [ 0.0 3.0 5.0 8.0 10.0;
+% 10.0 10.0 10.0 10.0 10.0;
+% 3.0 5.0 8.0 6.0 10.0];
+% crv2 = nrbmak(pnts, [0 0 0 1/3 2/3 1 1 1]);
+%
+% pnts= [ 0.0 0.0 0.0 0.0;
+% 0.0 3.0 8.0 10.0;
+% 2.0 0.0 5.0 3.0];
+% crv3 = nrbmak(pnts, [0 0 0 0.5 1 1 1]);
+%
+% pnts= [ 10.0 10.0 10.0 10.0 10.0;
+% 0.0 3.0 5.0 8.0 10.0;
+% 9.0 7.0 7.0 10.0 10.0];
+% crv4 = nrbmak(pnts, [0 0 0 0.25 0.75 1 1 1]);
+%
+% srf = nrbcoons(crv1, crv2, crv3, crv4);
+% nrbplot(srf,[20 20],220,45);
+%
+% Copyright (C) 2000 Mark Spink
+%
+% This program is free software: you can redistribute it and/or modify
+% it under the terms of the GNU General Public License as published by
+% the Free Software Foundation, either version 2 of the License, or
+% (at your option) any later version.
+
+% This program is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+if nargin ~= 4
+ error('Incorrect number of input arguments');
+end
+
+r1 = nrbruled(u1, u2);
+r2 = nrbtransp(nrbruled(v1, v2));
+t = nrb4surf(u1.coefs(:,1), u1.coefs(:,end), u2.coefs(:,1), u2.coefs(:,end));
+
+% raise all surfaces to a common degree
+du = max([r1.order(1), r2.order(1), t.order(1)]);
+dv = max([r1.order(2), r2.order(2), t.order(2)]);
+r1 = nrbdegelev(r1, [du - r1.order(1), dv - r1.order(2)]);
+r2 = nrbdegelev(r2, [du - r2.order(1), dv - r2.order(2)]);
+t = nrbdegelev(t, [du - t.order(1), dv - t.order(2)]);
+
+% merge the knot vectors, to obtain a common knot vector
+
+% U knots
+k1 = r1.knots{1};
+k2 = r2.knots{1};
+k3 = t.knots{1};
+k = unique([k1 k2 k3]);
+n = length(k);
+kua = [];
+kub = [];
+kuc = [];
+for i = 1:n
+ i1 = length(find(k1 == k(i)));
+ i2 = length(find(k2 == k(i)));
+ i3 = length(find(k3 == k(i)));
+ m = max([i1, i2, i3]);
+ kua = [kua k(i)*ones(1,m-i1)];
+ kub = [kub k(i)*ones(1,m-i2)];
+ kuc = [kuc k(i)*ones(1,m-i3)];
+end
+
+% V knots
+k1 = r1.knots{2};
+k2 = r2.knots{2};
+k3 = t.knots{2};
+k = unique([k1 k2 k3]);
+n = length(k);
+kva = [];
+kvb = [];
+kvc = [];
+for i = 1:n
+ i1 = length(find(k1 == k(i)));
+ i2 = length(find(k2 == k(i)));
+ i3 = length(find(k3 == k(i)));
+ m = max([i1, i2, i3]);
+ kva = [kva k(i)*ones(1,m-i1)];
+ kvb = [kvb k(i)*ones(1,m-i2)];
+ kvc = [kvc k(i)*ones(1,m-i3)];
+end
+
+r1 = nrbkntins(r1, {kua, kva});
+r2 = nrbkntins(r2, {kub, kvb});
+t = nrbkntins(t, {kuc, kvc});
+
+% combine coefficient to construct Coons surface
+coefs(1,:,:) = r1.coefs(1,:,:) + r2.coefs(1,:,:) - t.coefs(1,:,:);
+coefs(2,:,:) = r1.coefs(2,:,:) + r2.coefs(2,:,:) - t.coefs(2,:,:);
+coefs(3,:,:) = r1.coefs(3,:,:) + r2.coefs(3,:,:) - t.coefs(3,:,:);
+coefs(4,:,:) = r1.coefs(4,:,:) + r2.coefs(4,:,:) - t.coefs(4,:,:);
+srf = nrbmak(coefs, r1.knots);
+
+end
+
+%!demo
+%! pnts = [ 0.0 3.0 4.5 6.5 8.0 10.0;
+%! 0.0 0.0 0.0 0.0 0.0 0.0;
+%! 2.0 2.0 7.0 4.0 7.0 9.0];
+%! crv1 = nrbmak(pnts, [0 0 0 1/3 0.5 2/3 1 1 1]);
+%!
+%! pnts= [ 0.0 3.0 5.0 8.0 10.0;
+%! 10.0 10.0 10.0 10.0 10.0;
+%! 3.0 5.0 8.0 6.0 10.0];
+%! crv2 = nrbmak(pnts, [0 0 0 1/3 2/3 1 1 1]);
+%!
+%! pnts= [ 0.0 0.0 0.0 0.0;
+%! 0.0 3.0 8.0 10.0;
+%! 2.0 0.0 5.0 3.0];
+%! crv3 = nrbmak(pnts, [0 0 0 0.5 1 1 1]);
+%!
+%! pnts= [ 10.0 10.0 10.0 10.0 10.0;
+%! 0.0 3.0 5.0 8.0 10.0;
+%! 9.0 7.0 7.0 10.0 10.0];
+%! crv4 = nrbmak(pnts, [0 0 0 0.25 0.75 1 1 1]);
+%!
+%! srf = nrbcoons(crv1, crv2, crv3, crv4);
+%!
+%! nrbplot(srf,[20 20]);
+%! title('Construction of a bilinearly blended Coons surface.');
+%! hold off
git://git.creatis.insa-lyon.fr / CreaPhase.git / blobdiff