## Mercurial > hg > octave-max

### view scripts/geometry/rectint.m @ 15489:481417a57a2d

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improve sign and signbit docs
* mappers.cc (Fsign): Note sign (-0) is 0. Add @seealso for signbit.
(Fsignbit): Add @seealso for sign.

author | John W. Eaton <jwe@octave.org> |
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date | Thu, 04 Oct 2012 10:20:59 -0400 |

parents | 86854d032a37 |

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## Copyright (C) 2008-2012 Bill Denney ## ## This file is part of Octave. ## ## Octave 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 3 of the License, or (at ## your option) any later version. ## ## Octave 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 Octave; see the file COPYING. If not, see ## <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} {@var{area} =} rectint (@var{a}, @var{b}) ## ## Compute the area of intersection of rectangles in @var{a} and ## rectangles in @var{b}. Rectangles are defined as [x y width height] ## where x and y are the minimum values of the two orthogonal ## dimensions. ## ## If @var{a} or @var{b} are matrices, then the output, @var{area}, is a ## matrix where the i-th row corresponds to the i-th row of a and the j-th ## column corresponds to the j-th row of b. ## ## @seealso{polyarea} ## @end deftypefn ## Author: Bill Denney <bill@denney.ws> function area = rectint (a, b) if (nargin != 2) print_usage (); elseif (ndims (a) != 2 || ndims (b) != 2) error ("rectint: expecting arguments to be 2-d arrays"); elseif (columns (a) != 4) error ("rectint: A must have 4 columns"); elseif (columns (b) != 4) error ("rectint: B must have 4 columns"); elseif (any ([a(:,3:4);b(:,3:4)](:) < 0)) error ("rectint: all widths and heights must be > 0"); endif ## This runs faster if the number of rows of a is greater than the ## number of rows of b. Swap them and transpose to make it run ## faster. swapinputs = false (); if (rows (a) > rows (b)) tmp = a; a = b; b = tmp; swapinputs = true (); endif area = zeros (rows (a), rows (b)); r1 = [a(:,1:2) a(:,1:2)+a(:,3:4)]; r2 = [b(:,1:2) b(:,1:2)+b(:,3:4)]; for i = 1:columns (area) ## Find the location of each point relative to the other points. r1x1small = r1(:,1) < r2(i,1); r1x1large = r1(:,1) > r2(i,3); r1x1mid = (r1(:,1) >= r2(i,1)) & (r1(:,1) <= r2(i,3)); r1x2small = r1(:,3) < r2(i,1); r1x2large = r1(:,3) > r2(i,3); r1x2mid = (r1(:,3) >= r2(i,1)) & (r1(:,3) <= r2(i,3)); r1y1small = r1(:,2) < r2(i,2); r1y1large = r1(:,2) > r2(i,4); r1y1mid = (r1(:,2) >= r2(i,2)) & (r1(:,2) <= r2(i,4)); r1y2small = r1(:,4) < r2(i,2); r1y2large = r1(:,4) > r2(i,4); r1y2mid = (r1(:,4) >= r2(i,2)) & (r1(:,4) <= r2(i,4)); ## determine the width of the rectangle ## r1 completely encloses r2 area(r1x1small & r1x2large,i) = r2(i,3) - r2(i,1); ## the range goes from r2x min to r1x max mask = r1x1small & r1x2mid; area(mask,i) = r1(mask,3) - r2(i,1); ## the range goes from r1x min to r2x max mask = r1x1mid & r1x2large; area(mask,i) = r2(i,3) - r1(mask,1); ## the range goes from r1x min to r1x max mask = r1x1mid & r1x2mid; area(mask,i) = r1(mask,3) - r1(mask,1); ## determine the height of the rectangle ## r1 completely encloses r2 area(r1y1small & r1y2large,i) .*= r2(i,4) - r2(i,2); ## the range goes from r2y min to r1y max mask = r1y1small & r1y2mid; area(mask,i) .*= r1(mask,4) - r2(i,2); ## the range goes from r1y min to r2y max mask = r1y1mid & r1y2large; area(mask,i) .*= r2(i,4) - r1(mask,2); ## the range goes from r1x min to r1x max mask = r1y1mid & r1y2mid; area(mask,i) .*= r1(mask,4) - r1(mask,2); endfor if (swapinputs) area = area'; endif endfunction ## Exactly overlapping %!assert (rectint ([0 0 1 1], [0 0 1 1]), 1) ## rect2 completely enclosed by rect1 %!assert (rectint ([-1 -1 3 3], [0 0 1 1]), 1) ## rect1 completely enclosed by rect2 %!assert (rectint ([0 0 1 1], [-1 -1 3 3]), 1) ## rect1 right and top in rect2 %!assert (rectint ([-1 -1 1.5 1.5], [0 0 1 1]), 0.25) ## rect2 right and top in rect1 %!assert (rectint ([0 0 1 1], [-1 -1 1.5 1.5]), 0.25) ## no overlap - shared corner %!assert (rectint ([0 0 1 1], [1 1 2 2]), 0) ## no overlap - shared edge %!assert (rectint ([0 0 1 1], [0 1 2 2]), 0) ## Correct orientation of output %!assert (rectint ([0 0 1 1;0.5 0.5 1 1;-1 -1 2 2], [1 1 2 2]), [0;0.25;0]) %!assert (rectint ([1 1 2 2], [0 0 1 1;0.5 0.5 1 1;-1 -1 2 2]), [0 0.25 0])