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## Copyright (C) 2024 David Legland
## All rights reserved.
##
## Redistribution and use in source and binary forms, with or without
## modification, are permitted provided that the following conditions are met:
##
## 1 Redistributions of source code must retain the above copyright notice,
## this list of conditions and the following disclaimer.
## 2 Redistributions in binary form must reproduce the above copyright
## notice, this list of conditions and the following disclaimer in the
## documentation and/or other materials provided with the distribution.
##
## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ''AS IS''
## AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
## IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
## ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
## ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
## DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
## SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
## CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
## OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
##
## The views and conclusions contained in the software and documentation are
## those of the authors and should not be interpreted as representing official
## policies, either expressed or implied, of the copyright holders.
function res = clipPolyline(poly, box)
%CLIPPOLYLINE Clip an open polyline with a rectangular box.
%
% POLY2 = clipPolyline(POLY, BOX);
% POLY is N-by-2 array of vertex coordinates.
% BOX has the form: [XMIN XMAX YMIN YMAX].
% Returns the set of polylines created by the intersection of the
% polyline POLY and the bounding box BOX. The result is a cell array with
% as many cells as the number of curve clips.
%
%
% Example
% circle = [5 5 6];
% poly = circleToPolygon(circle, 200);
% box = [0 10 0 10];
% res = clipPolyline(poly, box);
% figure;
% hold on; axis equal; axis([-2 12 -2 12]);
% drawCircle(circle, 'b:')
% drawBox(box, 'k')
% drawPolyline(res, 'linewidth', 2, 'color', 'b')
%
% See also
% polygons2d, boxes2d, clipPolygon, clipEdge
%
% ------
% Author: David Legland
% E-mail: david.legland@inrae.fr
% Created: 2005-05-14
% Copyright 2005-2023 INRA - Cepia Software Platform
% check case of polylines stored in cell array
if iscell(poly)
res = cell(1, length(poly));
for i = 1:length(poly)
res{i} = clipPolyline(poly{i}, box);
end
return;
end
% check case of empty polylines
N = size(poly, 1);
if N == 0
res = cell(0, 0);
return
end
% create edges array of polyline
edges = [poly(1:N-1, :) poly(2:N, :)];
% clip edges
edges = clipEdge(edges, box);
% select non empty edges, and get their vertices
% find clipped edges within box
inds = sum(abs(edges), 2) > 1e-14;
% find list of adjacent edges within box
dinds = diff(inds);
inds0 = find(dinds == 1) + 1;
if inds(1) == 1
inds0 = [1 inds0];
end
inds1 = find(dinds == -1);
if inds(end) == 1
inds1 = [inds1 N-1];
end
nClips = length(inds0);
res = cell(1, nClips);
for iClip = 1:nClips
range = inds0(iClip):inds1(iClip);
poly2 = [edges(range, 1:2) ; edges(range(end), 3:4)];
res{iClip} = poly2;
end
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