RosettaCodeData/Task/Fractal-tree/Liberty-BASIC/fractal-tree.basic

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NoMainWin
sw = 640 : sh = 480
WindowWidth = sw+8 : WindowHeight = sh+31
UpperLeftX = (DisplayWidth -sw)/2
UpperLeftY = (DisplayHeight-sh)/2
Open"Fractal Tree" For Graphics_nf_nsb As #g
#g "Down; Color darkgreen; TrapClose halt"
h$ = "#g"
'initial assignments
initAngle = Acs(-1)*1.5 'radian equivalent of 270 degrees
theta = 29 * (Acs(-1)/180) 'convert 29 degrees to radians
length = 110 'length in pixels
depth = 25 'max recursion depth
'draw the tree
Call tree h$, 320, 470, initAngle, theta, length, depth
#g "Flush; when leftButtonDown halt" 'L-click to exit
Wait
Sub halt handle$
Close #handle$
End
End Sub
Sub tree h$, x, y, initAngle, theta, length, depth
Scan
newX = Cos(initAngle) * length + x
newY = Sin(initAngle) * length + y
#h$ "Line ";x;" ";y;" ";newX;" ";newY
length = length * .78
depth = depth - 1
If depth > 0 Then
Call tree h$, newX, newY, initAngle-theta, theta, length, depth
Call tree h$, newX, newY, initAngle+theta, theta, length, depth
End If
End Sub