Maptitude - http://research.umbc.edu/~roswell/maptitude.html
I am sorry, in my previous posting I sent the macro with some commented lines that
I was using for testing.
Please, disregard the previous email, here is the correct version of the macro
Cheers,
Armando Scalise
================
Macro "shared_edges" (rh1,rh2)
// This macro computes the lenght of shared boundaries between two polygons
// It creates an array with all the lines in polygon 1 in a clockwise direction and
an array in counterclockwise direction
// It also creates an array of all lines in polygon 2, in clockwise direction
// It proceeds looking for lines in polygon 2 that matches start and end
coordinates in the counterclockwise OR the anticlockwuse lines array of polygon 2
// when a match is found, the length of that line is computed.
// it returns the lenght of the common boundary, or null if any of the input
parameters is null
// Written by Armando Scalise, [EMAIL PROTECTED] Phone: +54 11 4432-2188
(Buenos Aires, Argentina)
// check input parameters
if rh1=null or rh2=null then Return(null)
// Get Polygon points
polys1=GetArea(rh2id(rh1))
polys2=GetArea(rh2id(rh2))
// Get First Polygon's borders clockwise
last= polys1[3][1]
for i=1 to polys1[3].length do
lines11=lines11+{{last,polys1[3][i]}}
last=polys1[3][i]
end
// Get first polygon's borders counter clockwise
last= polys1[3][polys1[3].length]
for i=polys1[3].length to 1 step -1 do
lines12=lines12+{{last,polys1[3][i]} }
last=polys1[3][i]
end
// Get Second Polygon's borders clockwise
last= polys2[3][1]
for i=1 to polys2[3].length do
lines2=lines2+{{last,polys2[3][i]}}
last=polys2[3][i]
end
// Look for matching borders
totdist=0
matches=null
for i=1 to lines2.length do
// check against clockwise coords.
for j=1 to lines11.length do
if lines2[i][1] =lines11[j][1] and lines2[i][2] =lines11[j][2]
then do
totdist=totdist+GetDistance(lines11[j][1],lines11[j][2])
end
end
// check against clockwise coords.
for j=1 to lines12.length do
if lines2[i][1] =lines12[j][1] and
lines2[i][2]=lines12[j][2]then do
totdist=totdist+GetDistance(lines12[j][1],lines12[j][2])
end
end
end
Return(totdist)
endMacro
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