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Active Forums => Programs => Topic started by: AndyA on April 16, 2021, 03:23:43 pm

Title: Barnsley Fern (Rosetta Code task)
Post by: AndyA on April 16, 2021, 03:23:43 pm
https://rosettacode.org/wiki/Barnsley_fern#QB64 (https://rosettacode.org/wiki/Barnsley_fern#QB64)

'==================================================
Task
Create this fractal fern, using the following transformations:

ƒ1   (chosen 1% of the time)
        xn + 1 = 0
        yn + 1 = 0.16 yn
ƒ2   (chosen 85% of the time)
        xn + 1 = 0.85 xn + 0.04 yn
        yn + 1 = −0.04 xn + 0.85 yn + 1.6
ƒ3   (chosen 7% of the time)
        xn + 1 = 0.2 xn − 0.26 yn
        yn + 1 = 0.23 xn + 0.22 yn + 1.6
ƒ4   (chosen 7% of the time)
        xn + 1 = −0.15 xn + 0.28 yn
        yn + 1 = 0.26 xn + 0.24 yn + 0.44.
Starting position: x = 0, y = 0
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Code: QB64: [Select]
  1. _Title "Barnsley Fern"
  2. Dim As Integer sw, sh
  3. sw = 400: sh = 600
  4. Screen _NewImage(sw, sh, 8)
  5.  
  6. Dim As Long i, ox, oy
  7. Dim As Single sRand
  8. Dim As Double x, y, x1, y1, sx, sy
  9. sx = 60: sy = 59
  10. ox = 180: oy = 4
  12.  
  13. x = 0
  14. y = 0
  15. For i = 1 To 400000
  16.     sRand = Rnd
  17.     Select Case sRand
  18.         Case Is < 0.01
  19.             x1 = 0: y1 = 0.16 * y
  20.         Case Is < 0.08
  21.             x1 = 0.2 * x - 0.26 * y: y1 = 0.23 * x + 0.22 * y + 1.6
  22.         Case Is < 0.15
  23.             x1 = -0.15 * x + 0.28 * y: y1 = 0.26 * x + 0.24 * y + 0.44
  24.         Case Else
  25.             x1 = 0.85 * x + 0.04 * y: y1 = -0.04 * x + 0.85 * y + 1.6
  26.     End Select
  27.     x = x1
  28.     y = y1
  29.     PSet (x * sx + ox, sh - (y * sy) - oy), 10
  31.  
Title: Re: Barnsley Fern (Rosetta Code task)
Post by: david_uwi on April 19, 2021, 03:56:58 am
Nice picture. Note:the DIMs have to be changed to the QB64 format for it to work.
NOT dim as integer I, dim I as integer (or have I got an old compiler).
Title: Re: Barnsley Fern (Rosetta Code task)
Post by: SMcNeill on April 19, 2021, 07:27:39 am
Quote from: david_uwi on April 19, 2021, 03:56:58 am
Nice picture. Note:the DIMs have to be changed to the QB64 format for it to work.
NOT dim as integer I, dim I as integer (or have I got an old compiler).

In version 1.5, we now support the new format you’re seeing.

Instead of:   DIM x AS INTEGER: DIM y AS NTEGER: DIM z AS INTEGER...

You can now:  DIM AS INTEGER x, y, z
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