/usr/share/octave/packages/mapping-1.2.1/private/clipplg.m is in octave-mapping 1.2.1-1+b1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 | ## Copyright (C) 2014 Philip Nienhuis
##
## 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 3 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/>.
## -*- texinfo -*-
## @deftypefn {Function File} [@var{val}, @var{npts}, @var{pptr}] = clipplg (@var{val}, @var{npts}, @var{pptr}, @var{sbox}[, @var{styp]})
## Undocumented internal function for clipping polygons & interpolating Z & M
## values.
##
## @seealso{}
## @end deftypefn
## Author: Philip Nienhuis <prnienhuis@users.sf.net>
## Created: 2014-11-18
## Updates:
## 2014-11-22 Create stanza for finding back vertices and interpolating Z & M
## 2014-11-25 Fix interpolating M & Z values, properly treat new corner points
## of clipped polygons
## 2014-11-26 Update tnpt and tnpr arrays
## 2015-07-10 Provision for segments crossed twice by clipping polygon
function [val, tnpt, tnpr] = clipplg (val, tnpt, tnpr, sbox, styp=5)
## Indices to start of each subfeature, plus end+1
tnprt = [(tnpr + 1) tnpt+1];
## Initialize total number of clipped vertices
tnptclp = 0;
tnprclp = cell (numel (tnpr, 1));
for kk=1:numel (tnpr)
## Work from end back to start of subfeatures to avoid mixing up index arrays
jj = numel (tnpr) - kk + 1;
## Select rows belonging to this partial feature. First save non-selected rows
b_val = e_val = [];
if (jj > 1)
## There's one or more subfeatures lower down
b_val = val(1:tnprt(jj)-1, :);
endif
if (jj < numel (tnpr))
## There's one or more subfeatures higher up
e_val = val(tnprt(jj+1):end, :);
endif
tval = val(tnprt(jj):tnprt(jj+1)-1, :);
## oc_polybool is in OF geometry package
[X, Y, npol, b, c] = oc_polybool (tval(:, 1:2), sbox, 'AND');
## Initialize new number of points & new part pointers in clipped polygon(s)
nptclp = 0;
nprclp = 0;
valn = [];
if (npol)
## Make an XY matrix, remove NaNs on upper and lower row
valc = [X Y](2:end-1, :);
## Augment NaNs for Z and M, and augment type + shape record index columns
ncl = size (valc, 1);
valc = [ valc NaN(ncl, 2) tval(1, 5)*ones(ncl, 1) tval(1, 6)*ones(ncl, 1) ];
## Pointers to subpolygons resulting from clipping
ipt = find (isnan (valc(:, 1)))';
ipt = [ 0 ipt (size (valc, 1) + 1) ];
## For each new polygon...
for ipol=1:npol
valn = valc(ipt(ipol)+1:ipt(ipol+1)-1, :);
## Update total number of points in clipped polygon(s)
nptclp += size (valn, 1);
tnptclp += size (valn, 1);
## Add a new 0-based pointer to next part
nprclp = [ nprclp nptclp ];
## Compute all interdistances. distancePoints is in OF geometry package
## Avoid polygon end point ( = start point)
dsts = distancePoints (valn(1:end-1, 1:2), tval(1:end-1, 1:2));
## Find matching points in sub and out polygon (row, col)
[rw, cl] = ind2sub (size (dsts), find (abs (dsts) < eps));
## Transfer known Z and M-values
valn(rw, 3:4) = tval(cl, 3:4);
## cl indices refer to original shape, rw indices to clipped shape
if (numel (cl) >= 1)
## Separate polygon segments clipped, or vertex on bounding box side
## For each valn row coords not in tval, interpolate Z and M values
im = setdiff ([1:size(valn, 1)-1], rw);
## mi equals cl filled with zeros for non-matches, to easen indexing
mi = zeros (1, size (valn, 1) - 1);
mi(rw) = cl;
## Find direction of polyline
pdir = find (abs (diff (rw)) - 1 < eps);
if (isempty (pdir))
## Single point within bounding box. Direction doesn't matter then
drctn = 1;
else
drctn = sign (diff (rw([pdir pdir+1])))(1);
endif
for ii=1:numel (im)
## Get matching outer vertex. Below IF-ELSEIF order = critical to
## avoid index out-of-range errors
if (im(ii) == 1)
## Clipped off outer vertex = previous in tval. diff(cl) = direction
intpl = true;
idx = mi(im(ii)+1) - drctn;
ovtx = tval(idx, :);
cvtx = tval(mi(im(ii)+1), :);
elseif ((! ismember (im(ii)-1, rw)) && (! ismember (im(ii)+1, rw)))
## Probably a corner point. Just retain NaN values
intpl = false;
elseif (! ismember (im(ii)-1, rw))
## Clipped off outer vertex = previous in tval. diff(cl) = direction
intpl = true;
idx = mi(im(ii)+1) - drctn;
ovtx = tval(idx, :);
cvtx = tval(mi(im(ii)+1), :);
elseif (! ismember (im(ii)+1, rw))
## Clipped off outer vertex = next in tval. diff(cl) = direction
intpl = true;
idx = mi(im(ii)-1) + drctn;
ovtx = tval(idx, :);
cvtx = tval(mi(im(ii)-1), :);
endif
## Parent points found, now interpolate M and Z (if appropriate)
if (intpl && styp > 5)
## Compute missing M and Z values. Invoke largest diff of X/Y coordinates
difx = abs (cvtx(1) - ovtx(1));
dify = abs (cvtx(2) - ovtx(2));
if (difx > dify)
## X distance is greater
fac = (valn(im(ii), 1) - cvtx(1)) / difx;
else
## Y distance is greater
fac = (valn(im(ii), 2) - cvtx(2)) / dify;
endif
fac = abs(fac);
## FIXME a debug stmt to detect wrong interpolation => wrong vertices
if (fac > 1.0)
printf ("Oops - fac > 1..\n");
% keyboard
endif
if (isfinite (ovtx(3)))
valn(im(ii), 3) = fac * (ovtx(3) - cvtx(3)) + cvtx(3); ## Z-value
endif
if (isfinite (ovtx(4)))
valn(im(ii), 4) = fac * (ovtx(4) - cvtx(4)) + cvtx(4); ## M-value
endif
endif
endfor
## Remove last nprclp entry and temporarily store it in a cell arr
tnprclp(jj) = nprclp;
elseif (numel (cl) == 0)
## One polygon segment clipped twice. Simply assign nearest Z & M values
## FIXME proper interpolation required
## Find points interpolated on segment(s); they're not in sbox
[im, ix] = min (distancePoints (sbox(1:end-1, :), valn(1:end-1, 1:2)));
im = find (im > 0);
ix = ix(im);
## Find nearest polygon points (could be on another polygon segment !)
[~, ix] = min (distancePoints (tval(1:end-1, 1:2), valn(im, 1:2)));
## Assign Z and M values
valn(im, 3:4) = tval(ix, 3:4);
## Remove last nprclp entry and temporarily store it in a cell arr
tnprclp(jj) = nprclp;
endif
## Last row of polygon equals first
valn(end, :) = valn(1, :);
## Augment new polygon after (yet untouched) previous polygons
b_val = [ b_val; valn ];
endfor ## clipped subpolygons
else
## No intersection at all. Just drop tval
% tnprclp = {};
endif
val = [b_val ; e_val];
tnprt(jj+1:end) -= tnprt(jj+1) - tnprt(jj) - size (valn, 1);
if (isempty (valn))
## This subfeature has no points in boundingbox +> drop from list
tnprt(jj+1) = [];
endif
endfor
## Adapt & clean up npt
tnpt = tnptclp;
## Adapt & clean up npr. Concatenate all pointers created by oc_polybool
tnpr = [ tnprclp{1} ];
for ii=2:numel (tnprclp)
## Skip empty entries
if (! isempty (tnprclp{ii}))
tnpr = [tnpr(1:end-1) (tnprclp{ii} + tnpr(end)) ];
endif
endfor
if (! isempty (tnpr))
tnpr(end) = [];
endif
endfunction
|