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quadString.m
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quadString.m
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quadString ; QuadString Library
; Copyright (C) 2008 Etienne Cherdlu <[email protected]>
;
; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU Affero 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 Affero General Public License for more details.
;
; You should have received a copy of the GNU Affero General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
llToQs(lat,lon) ; Public ; Convert lat/lon to quadString
;
n qsTile,latIncrement,lonIncrement,zoom
;
s qsTile=""
s latIncrement=90
s lonIncrement=180
;
f zoom=1:1:15 d
. s latIncrement=latIncrement/2
. s lonIncrement=lonIncrement/2
. i lat<0,lon<0 s lat=lat+latIncrement,lon=lon+lonIncrement,qsTile=qsTile_"c" q
. i lat<0 s lat=lat+latIncrement,lon=lon-lonIncrement,qsTile=qsTile_"d" q
. i lon<0 s lat=lat-latIncrement,lon=lon+lonIncrement,qsTile=qsTile_"a" q
. s lat=lat-latIncrement,lon=lon-lonIncrement,qsTile=qsTile_"b" q
;
q qsTile
qsToLl(qsItem) ; Public ; Convert quadString to lat/lon
;
n lat,lon
;
s lat=0,lon=0
;
d qsToLl1(qsItem,.lat,.lon,90,180)
;
q lat_","_lon
qsToLl1(qsItem,lat,lon,latIncrement,lonIncrement) ;
;
n tile
;
s tile=$e(qsItem,1) i tile="" q
;
s latIncrement=latIncrement/2
s lonIncrement=lonIncrement/2
;
i tile="a" s lat=lat+latIncrement,lon=lon-lonIncrement
i tile="b" s lat=lat+latIncrement,lon=lon+lonIncrement
i tile="c" s lat=lat-latIncrement,lon=lon-lonIncrement
i tile="d" s lat=lat-latIncrement,lon=lon+lonIncrement
;
d qsToLl1($e(qsItem,2,$l(qsItem)),.lat,.lon,latIncrement,lonIncrement)
;
q
qsToBbox(qsItem,bllat,bllon,trlat,trlon) ; Public ; Convert quadString to bbox
;
s bllat=-90,bllon=-180,trlat=90,trlon=180
;
d qsToBbox1(qsItem,.bllat,.bllon,.trlat,.trlon,90,180)
;
q
qsToBbox1(qsItem,bllat,bllon,trlat,trlon,latIncrement,lonIncrement) ;
;
n tile
;
s tile=$e(qsItem,1)
;
i tile="a" s bllat=bllat+latIncrement,trlon=trlon-lonIncrement
i tile="b" s bllat=bllat+latIncrement,bllon=bllon+lonIncrement
i tile="c" s trlat=trlat-latIncrement,trlon=trlon-lonIncrement
i tile="d" s trlat=trlat-latIncrement,bllon=bllon+lonIncrement
;
i $l(qsItem)>1 d qsToBbox1($e(qsItem,2,$l(qsItem)),.bllat,.bllon,.trlat,.trlon,latIncrement/2,lonIncrement/2)
;
q
qsRoot(qsRoot,qsItem) ; Public ; Return common root of two quadStrings
;
n x
;
f x=$l(qsRoot):-1:0 i $e(qsItem,1,x)=$e(qsRoot,1,x) s qsRoot=$e(qsRoot,1,x) q
q qsRoot
bbox(bllat,bllon,trlat,trlon) ; Public ; Return quadString for a given bounding box
;
n qsbl,qstl,qsbr,qstr,qsRoot
;
s qsbl=$$llToQs(bllat,bllon)
s qstl=$$llToQs(trlat,bllon)
s qsbr=$$llToQs(bllat,trlon)
s qstr=$$llToQs(trlat,trlon)
s qsRoot=qsbl
s qsRoot=$$qsRoot^quadString(qsRoot,qstl)
s qsRoot=$$qsRoot^quadString(qsRoot,qsbr)
s qsRoot=$$qsRoot^quadString(qsRoot,qstr)
;
q qsRoot
bboxInQs(bbox,qsItem) ; Public ; Is any part of this bbox contained within this quadString?
;
n bllat,bllon,trlat,trlon
;
d qsToBbox(qsItem,.bllat,.bllon,.trlat,.trlon)
;
q $$overlap(bllat,bllon,trlat,trlon,bbox("bllat"),bbox("bllon"),bbox("trlat"),bbox("trlon"))
incrementQs(qsItem) ; Public ; Add 1 to a quadTile number (eg aaa+1=aab, abd+1=aca)
;
n rest,last
;
; ddd+1 returns null
i $tr(qsItem,"d","")="" q ""
;
s rest=$e(qsItem,1,$l(qsItem)-1)
s last=$e(qsItem,$l(qsItem))
;
i last="d" s rest=$$incrementQs(rest) q rest
i last="c" s last="d"
i last="b" s last="c"
i last="a" s last="b"
q rest_last
overlap(bllat1,bllon1,trlat1,trlon1,bllat2,bllon2,trlat2,trlon2) ;
;
; Algorithm from http://www.siliconchisel.com/Articles/Development_&_Tools/Fast_Window_Overlap_Checking_Algorithm/
;
i ((trlat1-bllat2)<0)'=((bllat1-trlat2)<0),((bllon1-trlon2)<0)'=((trlon1-bllon2)<0) q 1
;
q 0