Convex hull: Difference between revisions
Added Arturo implementation
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Drkameleon (talk | contribs) (Added Arturo implementation) |
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Line 104:
<pre>[ (-9,-3)(-3,-9)( 19,-8)( 17, 5)( 12, 17)( 5, 19)(-3, 15) ]
</pre>
=={{header|Arturo}}==
<lang rebol>define :point [x y][]
orientation: function [P Q R][
val: sub (Q\y - P\y)*(R\x - Q\x) (Q\x - P\x)*(R\y - Q\y)
if val=0 -> return 0
if val>0 -> return 1
return 2
]
calculateConvexHull: function [points][
result: new []
if 3 > size points [
loop points 'p -> 'result ++ p
]
indexMinX: 0
loop.with:'i points 'p [
if p\x < get points\[indexMinX] 'x ->
indexMinX: i
]
p: indexMinX
q: 0
while [true][
'result ++ points\[p]
q: (p + 1) % size points
loop 0..dec size points 'i [
if 2 = orientation points\[p] points\[i] points\[q] ->
q: i
]
p: q
if p=indexMinX -> break
]
return result
]
points: @[
to :point [16 3],
to :point [12 17],
to :point [0 6],
to :point @[neg 4 neg 6],
to :point [16 6],
to :point @[16 neg 7],
to :point @[17 neg 4],
to :point [5 19],
to :point @[19 neg 8],
to :point [3 16],
to :point [12 13],
to :point @[3 neg 4],
to :point [17 5],
to :point @[neg 3 15],
to :point @[neg 3 neg 9],
to :point [0 11],
to :point @[neg 9 neg 3],
to :point @[neg 4 neg 2],
to :point [12 10]
]
hull: calculateConvexHull points
loop hull 'i ->
print i</lang>
{{out}}
<pre>[x:-9 y:-3]
[x:-3 y:-9]
[x:19 y:-8]
[x:17 y:5]
[x:12 y:17]
[x:5 y:19]
[x:-3 y:15]</pre>
=={{header|C}}==
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