;  Examples of turtle graphics procedures.


; *********************************************************************
;  snowflake      size depth-limit
;     The Koch snowflake.
;  snowflake 100 3

make "snowflake [
   procedure [ [ :size :depth ] [ ] [ :d ] ]
   make "d * 0.577350269189626 :size
   pu
   bk :d
   lt 30
   pd
   flake :size :depth
   rt 120
   flake :size :depth
   rt 120
   flake :size :depth
   rt 150
   pu
   fd :d
   pd ]

;  One side of the snowflake.

make "flake [
   procedure [ [ :size :depth ] ]
   if =0 :depth [ fd :size stop ] [ ]
   make "size / :size 3
   make "depth - :depth 1
   flake :size :depth
   lt 60
   flake :size :depth
   rt 120
   flake :size :depth
   lt 60
   flake :size :depth ]

; *********************************************************************
;  inspi          size angle increment ( turtle-pointer )
;     An angle increment spiral.
;  inspi 3 0 7
;  inspi 8 2 20

make "inspi [
   procedure [ [ :side :angle :inc ] [ :tp ] [ :h :a ] ]
   if listp :tp [ make "tp :t1 ] [ ]
   make "h heading :tp
   make "a :angle
   dowhile
   [  fd :side
      rt :angle
      make "angle remainder + :angle :inc 360 ]
   [  not and = :h heading :tp = :angle :a ] ]

; *********************************************************************
;  cornerpoly     size angle depth-limit factor
;     polygon with more polygons at it's corners.
;  cornerpoly 40 144 3 0.4
;  cornerpoly 30 90 4 0.5
;  cornerpoly 40 150 3 0.25

make "cornerpoly [
   procedure [ [ :size :angle :limit :factor ] [ ] [ :totalturn ] ]
   if =0 :limit [ stop ] [ ]
   make "totalturn 0
   dowhile 
   [  fd :size
      cornerpoly * :factor :size +- :angle - :limit 1 :factor
      rt :angle
      make "totalturn + :totalturn :angle ]
   [  not =0 remainder :totalturn 360 ] ]

; *********************************************************************
;  starspi
;     Crazy spirals.

make "starspi [
   procedure [ [ ] [ ] [ :r1 :r2 :a1 :a2 :d :df ] ]
   clean
   home
   setrgb :s1 1 item + 1 random 7   [  [ 15 15 15 ]
                                       [ 15 0  0 ]
                                       [ 15 15 0 ]
                                       [ 0  15 0 ]
                                       [ 0  15 15 ]
                                       [ 3  2  15 ]
                                       [ 15 0  15 ] ]
   make "r1 + 30 random 25
   make "r2 + 3 random 5
   make "a1 * rand 360
   make "a2 * rand 180
   make "d 5
   make "df + 1.05 * 0.25 rand
   repeat :r1 [
      repeat :r2 [
         fd :d
         rt :a2 ]
      make "d * :d :df
      rt :a1 ]
   starspi
   stop ]

; *********************************************************************
;  tree           size size-limit factor angle
;     A simple turtle tree.
;  tree 50 5 0.5 45
;  tree 50 2 0.7 90
;  tree 40 3 0.6 15

make "tree [
   procedure [ [ :size :limit :f :angle ] ]
   if < :size :limit [ fd :size bk :size stop ] [ ]
   fd :size
   rt :angle
   tree * :size :f :limit :f :angle
   lt + :angle :angle
   tree * :size :f :limit :f :angle
   rt :angle
   bk :size ]

; *********************************************************************
;  leantree       size angle depth-limit
;     Another simple turtle tree.
;  leantree 10 25 6
;  leantree 8 10 8

make "leantree [
   procedure [ [ :size :angle :level ] ]
   fd :size
   ltree :size :angle :level
   bk :size ]

make "ltree [
   procedure [ [ :size :angle :level ] ]
   if =0 :level [ stop ] [ ]
   lt :angle
   fd :size
   ltree :size :angle - :level 1
   bk :size
   rt * 2 :angle
   fd / :size 2
   ltree :size :angle - :level 1
   bk / :size 2
   lt :angle ]

; *********************************************************************
;  sidetree
;     Yet another tree.
;  sidetree 6 0.5 10 55 0.75 0.65

make "sidetree [
   procedure [ [  :size
                  :size-limit
                  :stem-angle
                  :branch-angle
                  :stem-factor
                  :branch-factor ] ]
   repeat 4
   [  rt :stem-angle
      fd :size ]
   if > :size :size-limit
   [  sidetree    * :size :stem-factor
                  :size-limit
                  :stem-angle
                  :branch-angle
                  :stem-factor
                  :branch-factor
      if >0 :stem-angle
      [  lt :branch-angle
         sidetree    * :size :branch-factor
                     :size-limit
                     +- :stem-angle
                     :branch-angle
                     :stem-factor
                     :branch-factor
         rt :branch-angle ]
      [  rt :branch-angle
         sidetree    * :size :branch-factor
                     :size-limit
                     +- :stem-angle
                     :branch-angle
                     :stem-factor
                     :branch-factor
         lt :branch-angle ] ] [ ]
   repeat 4
   [  bk :size
      lt :stem-angle ] ]

; *********************************************************************
;  fern           size size-limit
;     A simple fern leaf (a three branch tree).
;  fern 50 0.5

make "fern [
   procedure [ [ :size :limit ] ]
   if > :limit :size [ stop ] [ ]
   fd * 0.18 :size
   rt 4
   fern * 0.82 :size :limit
   rt 58
   fern * 0.3 :size :limit
   lt 122
   fern * 0.3 :size :limit
   rt 60
   bk * 0.18 :size ]

; *********************************************************************
;  fern2          size size-limit curl thickness node-spacing branch-angle
;     A more versatile fern leaf.
;  fern2 90 3 2 0.2 0.1 60
;  fern2 90 3 2 0.3 0.18 60
;  fern2 90 2 4 0.35 0.3 60

make "fern2 [
   procedure [ [ :size :limit :curl :thick :nspace :angle ] [ ]
               [ :d1 :d2 :a1 ] ]
   make "d1 * :size :nspace
   make "d2 * - 1 :nspace :size
   fd :d1
   if > :limit :size
   [  make "a1 atan / :thick - 1 :nspace
      fd :d2
      rt :a1
      bk :d2
      fd :d2
      lt + :a1 :a1
      bk :d2
      fd :d2
      rt :a1
      bk :d2 ]
   [  rt :curl
      fern2 :d2 :limit :curl :thick :nspace :angle
      rt - :angle :curl
      fern2 * :thick :size :limit :curl :thick :nspace :angle
      lt + :angle :angle
      fern2 * :thick :size :limit :curl :thick :nspace :angle
      rt :angle ]
   bk :d1 ]

; *********************************************************************
;  golden-rect    size
;     Golden mean rectangle.

make "golden-rect [
   procedure [ [ :size ] [ ] [ :m1 :m2 ] ]
   make "m1 1.61803398874989
   while [ not = :m1 :m2 ] [
      make "m2 :m1
      make "m1 + / 1 :m1 1 ]
   golden-rect1 :size ]

make "golden-rect1 [
   procedure [ [ :size ] [ ] [ :ms ] ]
   make "ms / :size :m1
   fd :size
   rt 90
   fd :ms   
   rt 90
   fd :size
   rt 90
   if < 0.2 :ms [ golden-rect1 :ms stop ] [ ] ]

; *********************************************************************
;  s-dragon       size size-limit angle
;     Size limit dragon.
;  s-dragon 50 5 45

make "s-dragon [
   procedure [ [ :size :size-limit :angle1 ] [ ] [ :leg1 :leg2 :angle2 ] ]
   make "angle2 - 90 :angle1
   make "leg1  /  * 0.5 sin - 180 * 2 :angle1  sin :angle1
   make "leg2  /  * 0.5 sin - 180 * 2 :angle2  sin :angle2
   s-dragon1 :size 1 ]

make "s-dragon1 [
   procedure [ [ :size :par ] ]
   if > :size-limit :size [ fd :size stop ] [ ]
   if >0 :par
      [  rt :angle1
         s-dragon1 * :size :leg1 1
         lt 90
         s-dragon1 * :size :leg2 -1
         rt :angle2 ]
      [  lt :angle2
         s-dragon1 * :size :leg2 1
         rt 90
         s-dragon1 * :size :leg1 -1
         lt :angle1 ] ]

;  Lots of dragons.

make "s-dragons [
   procedure [ [ ] [ ] [ :angle :size-limit ] ]
   make "size-limit 80
   while [ make "size-limit / :size-limit 3  > :size-limit 0.5 ] [
      make "angle 0
      while [ make "angle + :angle 5  < :angle 90 ] [
         clean
         home
         pu
         lt 70
         bk 52
         lt 20
         pd
         s-dragon 100 :size-limit :angle ] ] ]

; *********************************************************************
;  d-dragon       size depth-limit angle
;     Depth limit dragon
;  d-dragon 50 5 45

make "d-dragon [
   procedure [ [ :size :depth-limit :angle1 ] [ ] [ :leg1 :leg2 :angle2 ] ]
   make "angle2 - 90 :angle1
   make "leg1  /  * 0.5 sin - 180 * 2 :angle1  sin :angle1
   make "leg2  /  * 0.5 sin - 180 * 2 :angle2  sin :angle2
   d-dragon1 :size :depth-limit 1 ]

make "d-dragon1 [
   procedure [ [ :size :depth-limit :par ] ]
   if > 1 :depth-limit [ fd :size stop ] [ ]
   make "depth-limit - :depth-limit 1
   if >0 :par
      [  rt :angle1
         d-dragon1 * :size :leg1 :depth-limit 1
         lt 90
         d-dragon1 * :size :leg2 :depth-limit -1
         rt :angle2 ]
      [  lt :angle2
         d-dragon1 * :size :leg2 :depth-limit 1
         rt 90
         d-dragon1 * :size :leg1 :depth-limit -1
         lt :angle1 ] ]

;  Lots of dragons.

make "d-dragons [
   procedure [ [ ] [ ] [ :angle :depth-limit ] ]
   make "depth-limit 3
   while [ make "depth-limit + :depth-limit 3  < :depth-limit 12 ] [
      make "angle 0
      while [ make "angle + :angle 5  < :angle 90 ] [
         clean
         home
         pu
         lt 70
         bk 52
         lt 20
         pd
         d-dragon 100 :depth-limit :angle ] ] ]


; *********************************************************************

pr [ ]
pr [ Examples of turtle graphics procedures. ]
pr [ ]