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Diffstat (limited to 'sourcecodes/bnt-master/KPMtools/polygon_intersect.m')
| -rw-r--r-- | sourcecodes/bnt-master/KPMtools/polygon_intersect.m | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/sourcecodes/bnt-master/KPMtools/polygon_intersect.m b/sourcecodes/bnt-master/KPMtools/polygon_intersect.m new file mode 100644 index 00000000..9289f612 --- /dev/null +++ b/sourcecodes/bnt-master/KPMtools/polygon_intersect.m @@ -0,0 +1,60 @@ +function [is,S] = isintpl(x1,y1,x2,y2) +% ISINTPL Check for intersection of polygons. +% [IS,S] = ISINTPL(X1,Y1,X2,Y2) Accepts coordinates +% X1,Y1 and X2, Y2 of two polygons. Returns scalar +% IS equal to 1 if these polygons intersect each other +% and 0 if they do not. +% Also returns Boolean matrix S of the size length(X1) +% by length(X2) so that {ij} element of which is 1 if +% line segments i to i+1 of the first polygon and +% j to j+1 of the second polygon intersect each other, +% 0 if they don't and .5 if they "touch" each other. + +% Copyright (c) 1995 by Kirill K. Pankratov, +% kirill@plume.mit.edu. +% 06/20/95, 08/25/95 + + + % Handle input ................................... +if nargin==0, help isintpl, return, end +if nargin<4 + error(' Not enough input arguments ') +end + + % Make column vectors and check sizes ............ +x1 = x1(:); y1 = y1(:); +x2 = x2(:); y2 = y2(:); +l1 = length(x1); +l2 = length(x2); +if length(y1)~=l1 | length(y2)~=l2 + error('(X1,Y1) and (X2,Y2) must pair-wise have the same length.') +end + + % Quick exit if empty +if l1<1 | l2<1, is = []; S = []; return, end + + % Check if their ranges are intersecting ......... +lim1 = [min(x1) max(x1)]'; +lim2 = [min(x2) max(x2)]'; +isx = interval(lim1,lim2); % X-ranges +lim1 = [min(y1) max(y1)]'; +lim2 = [min(y2) max(y2)]'; +isy = interval(lim1,lim2); % Y-ranges +is = isx & isy; +S = zeros(l2,l1); + +if ~is, return, end % Early exit if disparate limits + + % Indexing ....................................... +[i11,i12] = meshgrid(1:l1,1:l2); +[i21,i22] = meshgrid([2:l1 1],[2:l2 1]); +i11 = i11(:); i12 = i12(:); +i21 = i21(:); i22 = i22(:); + + % Calculate matrix of intersections .............. +S(:) = iscross([x1(i11) x1(i21)]',[y1(i11) y1(i21)]',... + [x2(i12) x2(i22)]',[y2(i12) y2(i22)]')'; + +S = S'; +is = any(any(S)); + |