Dragon curve: Difference between revisions
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→{{header|Logo}}: add a bit-twiddling iterative version |
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=={{header|Logo}}==
===Recursive===
<lang logo>to dcr :step :length
make "step :step - 1
Line 1,060 ⟶ 1,061:
if :step=1 [Rt 180 fd :length Lt 180] [O (:step - 1) (:length / 1.41421) S (:step - 1) (:length / 1.41421)]
end</lang>
===Iterative===
Or drawing iteratively by making a turn left or right at each point calculated by bit-twiddling. This allows any length to be drawn, not just powers-of-2. Tested in ucblogo 5.5 and 6.0.
<lang logo>; Return the bit above the lowest 1-bit in :n.
; If :n = binary "...z100..00" then the return is "z000..00".
; Eg. n=22 is binary 10110 the lowest 1-bit is the "...1." and the return is
; bit above that "..1.," which is 4.
to bit.above.lowest.1bit :n
output bitand :n (1 + (bitxor :n (:n - 1)))
end
; Return angle +90 or -90 for dragon curve turn at point :n.
; The curve is reckoned as starting from n=0 so the first turn is at n=1.
to dragon.turn.angle :n
output ifelse (bit.above.lowest.1bit :n) = 0 [90] [-90]
end
; Draw :steps many segments of the dragon curve.
to dragon :steps
localmake "step.len 12 ; length of each step
repeat :steps [
forward :step.len
left dragon.turn.angle repcount ; repcount = 1 to :steps inclusive
]
end
dragon 256</lang>
<lang logo>; Draw :steps many segments of the dragon curve, with corners chamfered
; off with little 45-degree diagonals.
; Done this way the vertices don't touch.
to dragon.chamfer :steps
localmake "step.len 12 ; length of each step
localmake "straight.frac 0.5 ; fraction of the step to go straight
localmake "straight.len :step.len * :straight.frac
localmake "diagonal.len (:step.len - :straight.len) * sqrt(1/2)
repeat :steps [
localmake "turn (dragon.turn.angle repcount)/2 ; +45 or -45
forward :straight.len
left :turn
forward :diagonal.len
left :turn
]
end
dragon.chamfer 256</lang>
=={{header|Lua}}==
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