--- /dev/null
+function surf = nrbrevolve(curve,pnt,vec,theta)
+
+%
+% NRBREVOLVE: Construct a NURBS surface by revolving a NURBS curve, or
+% construct a NURBS volume by revolving a NURBS surface.
+%
+% Calling Sequence:
+%
+% srf = nrbrevolve(crv,pnt,vec[,ang])
+%
+% INPUT:
+%
+% crv : NURBS curve or surface to revolve, see nrbmak.
+%
+% pnt : Coordinates of the point used to define the axis
+% of rotation.
+%
+% vec : Vector defining the direction of the rotation axis.
+%
+% ang : Angle to revolve the curve, default 2*pi
+%
+% OUTPUT:
+%
+% srf : constructed surface or volume
+%
+% Description:
+%
+% Construct a NURBS surface by revolving the profile NURBS curve around
+% an axis defined by a point and vector.
+%
+% Examples:
+%
+% Construct a sphere by rotating a semicircle around a x-axis.
+%
+% crv = nrbcirc(1.0,[0 0 0],0,pi);
+% srf = nrbrevolve(crv,[0 0 0],[1 0 0]);
+% nrbplot(srf,[20 20]);
+%
+% NOTE:
+%
+% The algorithm:
+%
+% 1) vectrans the point to the origin (0,0,0)
+% 2) rotate the vector into alignment with the z-axis
+%
+% for each control point along the curve
+%
+% 3) determine the radius and angle of control
+% point to the z-axis
+% 4) construct a circular arc in the x-y plane with
+% this radius and start angle and sweep angle theta
+% 5) combine the arc and profile, coefs and weights.
+%
+% next control point
+%
+% 6) rotate and vectrans the surface back into position
+% by reversing 1 and 2.
+%
+%
+% Copyright (C) 2000 Mark Spink
+% Copyright (C) 2010 Rafael Vazquez
+%
+% 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 < 3)
+ error('Not enough arguments to construct revolved surface');
+end
+
+if (nargin < 4)
+ theta = 2.0*pi;
+end
+
+if (iscell (curve.knots) && numel(curve.knots) == 3)
+ error('The function nrbrevolve is not yet ready to create volumes')
+end
+
+% Translate curve the center point to the origin
+if isempty(pnt)
+ pnt = zeros(3,1);
+end
+
+if length(pnt) ~= 3
+ error('All point and vector coordinates must be 3D');
+end
+
+% Translate and rotate the original curve or surface into alignment with the z-axis
+T = vectrans(-pnt);
+angx = vecangle(vec(1),vec(3));
+RY = vecroty(-angx);
+vectmp = RY*[vecnorm(vec(:));1.0];
+angy = vecangle(vectmp(2),vectmp(3));
+RX = vecrotx(angy);
+curve = nrbtform(curve,RX*RY*T);
+
+% Construct an arc
+arc = nrbcirc(1.0,[],0.0,theta);
+
+if (iscell (curve.knots))
+% Construct the revolved volume
+ coefs = zeros([4 arc.number curve.number]);
+ angle = squeeze (vecangle(curve.coefs(2,:,:),curve.coefs(1,:,:)));
+ radius = squeeze (vecmag(curve.coefs(1:2,:,:)));
+ for i = 1:curve.number(1)
+ for j = 1:curve.number(2)
+ coefs(:,:,i,j) = vecrotz(angle(i,j))*vectrans([0.0 0.0 curve.coefs(3,i,j)])*...
+ vecscale([radius(i,j) radius(i,j)])*arc.coefs;
+ coefs(4,:,i,j) = coefs(4,:,i,j)*curve.coefs(4,i,j);
+ end
+ end
+ surf = nrbmak(coefs,{arc.knots, curve.knots{:}});
+else
+% Construct the revolved surface
+ coefs = zeros(4, arc.number, curve.number);
+ angle = vecangle(curve.coefs(2,:),curve.coefs(1,:));
+ radius = vecmag(curve.coefs(1:2,:));
+ for i = 1:curve.number
+ coefs(:,:,i) = vecrotz(angle(i))*vectrans([0.0 0.0 curve.coefs(3,i)])*...
+ vecscale([radius(i) radius(i)])*arc.coefs;
+ coefs(4,:,i) = coefs(4,:,i)*curve.coefs(4,i);
+ end
+ surf = nrbmak(coefs,{arc.knots, curve.knots});
+end
+
+% Rotate and vectrans the surface back into position
+T = vectrans(pnt);
+RX = vecrotx(-angy);
+RY = vecroty(angx);
+surf = nrbtform(surf,T*RY*RX);
+
+end
+
+%!demo
+%! sphere = nrbrevolve(nrbcirc(1,[],0.0,pi),[0.0 0.0 0.0],[1.0 0.0 0.0]);
+%! nrbplot(sphere,[40 40],'light','on');
+%! title('Ball and tori - surface construction by revolution');
+%! hold on;
+%! torus = nrbrevolve(nrbcirc(0.2,[0.9 1.0]),[0.0 0.0 0.0],[1.0 0.0 0.0]);
+%! nrbplot(torus,[40 40],'light','on');
+%! nrbplot(nrbtform(torus,vectrans([-1.8])),[20 10],'light','on');
+%! hold off;
+
+%!demo
+%! pnts = [3.0 5.5 5.5 1.5 1.5 4.0 4.5;
+%! 0.0 0.0 0.0 0.0 0.0 0.0 0.0;
+%! 0.5 1.5 4.5 3.0 7.5 6.0 8.5];
+%! crv = nrbmak(pnts,[0 0 0 1/4 1/2 3/4 3/4 1 1 1]);
+%!
+%! xx = vecrotz(deg2rad(25))*vecroty(deg2rad(15))*vecrotx(deg2rad(20));
+%! nrb = nrbtform(crv,vectrans([5 5])*xx);
+%!
+%! pnt = [5 5 0]';
+%! vec = xx*[0 0 1 1]';
+%! srf = nrbrevolve(nrb,pnt,vec(1:3));
+%!
+%! p = nrbeval(srf,{linspace(0.0,1.0,100) linspace(0.0,1.0,100)});
+%! surfl(squeeze(p(1,:,:)),squeeze(p(2,:,:)),squeeze(p(3,:,:)));
+%! title('Construct of a 3D surface by revolution of a curve.');
+%! shading interp;
+%! colormap(copper);
+%! axis equal;
+%! hold off
+
+%!demo
+%! crv1 = nrbcirc(1,[0 0],0, pi/2);
+%! crv2 = nrbcirc(2,[0 0],0, pi/2);
+%! srf = nrbruled (crv1, crv2);
+%! srf = nrbtform (srf, [1 0 0 0; 0 1 0 1; 0 0 1 0; 0 0 0 1]);
+%! vol = nrbrevolve (srf, [0 0 0], [1 0 0], pi/2);
+%! nrbplot(vol, [30 30 30], 'light', 'on')
git://git.creatis.insa-lyon.fr / CreaPhase.git / blobdiff