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1 | 1 | function Get-Turtle { |
2 | 2 | <# |
3 | 3 | .SYNOPSIS |
4 | | - Gets Turtle in PowerShell |
| 4 | + Gets Turtles |
5 | 5 | .DESCRIPTION |
6 | | - Gets, sets, and moves a turtle object in PowerShell. |
| 6 | + Gets turtles in a PowerShell. |
7 | 7 | .NOTES |
8 | | - Each argument can be the name of a member of the turtle object. |
| 8 | + Turtle Graphics are pretty groovy. |
| 9 | + |
| 10 | + They have been kicking it since 1966, and they are how computers first learned to draw. |
9 | 11 |
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10 | | - After a member name is encountered, subsequent arguments will be passed to the member as parameters. |
| 12 | + They kicked off the first computer-aided design boom and inspired generations of artists, engineers, mathematicians, and physicists. |
| 13 | +
|
| 14 | + They are also _incredibly_ easy to build. |
| 15 | +
|
| 16 | + A Turtle graphic is described with a series of moves. |
| 17 | +
|
| 18 | + Let's start with the core three moves: |
| 19 | + |
| 20 | + Imagine you are a Turtle holding a pen. |
| 21 | +
|
| 22 | + * You can turn `rotate` |
| 23 | + * You can move `forward` |
| 24 | + * You can lift the pen |
| 25 | +
|
| 26 | + These are the three basic moves a turtle can make. |
| 27 | + |
| 28 | + We can describe more complex moves by combining these steps. |
| 29 | +
|
| 30 | + Each argument can be the name of a move of the turtle object. |
| 31 | +
|
| 32 | + After a member name is encountered, subsequent arguments will be passed to the member as parameters. |
| 33 | + .EXAMPLE |
| 34 | + # We can write shapes as a series of steps |
| 35 | + turtle rotate 120 forward 42 rotate 120 forward 42 rotate 120 forward 42 |
11 | 36 | .EXAMPLE |
12 | | - turtle square 50 |
| 37 | + # We can also use a method. |
| 38 | + # Polygon will draw an an N-sided polygon. |
| 39 | + turtle polygon 10 5 |
13 | 40 | .EXAMPLE |
| 41 | + # A simple case of this is a square |
| 42 | + turtle square 42 |
| 43 | + .EXAMPLE |
| 44 | + # If we rotate 45 degrees first, our square becomes a rhombus |
| 45 | + turtle rotate 45 square 42 |
| 46 | + .EXAMPLE |
| 47 | + # We can draw a circle |
14 | 48 | turtle circle 10 |
15 | 49 | .EXAMPLE |
16 | | - turtle polygon 10 6 |
| 50 | + # Or a pair of half-circles |
| 51 | + turtle circle 10 0.5 rotate 90 circle 10 0.5 |
17 | 52 | .EXAMPLE |
| 53 | + # We can multiply arrays in PowerShell |
| 54 | + # this can make composing complex shapes easier. |
| 55 | + # Let's take the previous example and repeat it 8 times. |
| 56 | + turtle @('circle',42,0.5,'rotate',90 * 8) |
| 57 | + .EXAMPLE |
| 58 | + # Let's make a triangle by multiplying steps |
18 | 59 | turtle ('forward', 10, 'rotate', 120 * 3) |
19 | | -
|
| 60 | + .EXAMPLE |
| 61 | + # Let's make a series of polygons, decreasing in size |
| 62 | + turtle polygon 10 6 polygon 10 5 polygon 10 4 polygon 10 3 |
| 63 | + .EXAMPLE |
| 64 | + # We can also use a loop to produce a series of steps |
| 65 | + # Let's extend our previous example and make 9 polygons |
| 66 | + turtle @( |
| 67 | + foreach ($n in 12..3) { |
| 68 | + 'polygon' |
| 69 | + 42 |
| 70 | + $n |
| 71 | + } |
| 72 | + ) |
| 73 | + .EXAMPLE |
| 74 | + # We can use the same trick to make successively larger polygons |
| 75 | + turtle @( |
| 76 | + $sideCount = 3..8 | Get-Random |
| 77 | + foreach ($n in 1..5) { |
| 78 | + 'polygon' |
| 79 | + $n * 10 |
| 80 | + $sideCount |
| 81 | + } |
| 82 | + ) |
| 83 | + .EXAMPLE |
| 84 | + # A flower is a series of repeated polygons and rotations |
| 85 | + turtle Flower |
| 86 | + .EXAMPLE |
| 87 | + # Flowers look pretty with any number of polygons |
| 88 | + turtle Flower 50 10 (3..12 | Get-Random) 36 |
| 89 | + .EXAMPLE |
| 90 | + # Flowers get less dense as we increase the angle and decrease the repetitions |
| 91 | + turtle Flower 50 15 (3..12 | Get-Random) 24 |
| 92 | + .EXAMPLE |
| 93 | + # Flowers get more dense as we decrease the angle and increase the repetitions. |
| 94 | + turtle Flower 50 5 (3..12 | Get-Random) 72 |
| 95 | + .EXAMPLE |
| 96 | + # We can draw a pair of arcs and turn back after each one |
| 97 | + turtle ArcRight 42 45 rotate (180 - 45) ArcRight 42 45 rotate (180 - 45) |
| 98 | + .EXAMPLE |
| 99 | + # We call this a 'petal' |
| 100 | + turtle Petal 42 60 |
| 101 | + .EXAMPLE |
| 102 | + # We can construct a flower out of petals |
| 103 | + turtle FlowerPetal |
| 104 | + .EXAMPLE |
| 105 | + # Adjusting the angle of the petal makes our petal wider or thinner |
| 106 | + turtle FlowerPetal 42 15 (20..60 | Get-Random) 24 |
| 107 | + .EXAMPLE |
| 108 | + # Flower Petals get more dense as we decrease the angle and increase repetitions |
| 109 | + turtle FlowerPetal 42 10 (10..50 | Get-Random) 36 |
| 110 | + .EXAMPLE |
| 111 | + # Flower Petals get less dense as we increase the angle and decrease repetitions |
| 112 | + turtle FlowerPetal 50 20 (20..72 | Get-Random) 18 |
| 113 | + .EXAMPLE |
| 114 | + # We can construct a 'scissor' by drawing two lines at an angle |
| 115 | + turtle Scissor 42 60 |
| 116 | + .EXAMPLE |
| 117 | + # Drawing a scissor does not change the heading |
| 118 | + # So we can create a zig-zag pattern by multiply scissors |
| 119 | + turtle @('Scissor',42,60 * 4) |
| 120 | + .EXAMPLE |
| 121 | + # Getting a bit more interesting, we can create a polygon out of scissors |
| 122 | + # We will continually rotate until we have turned a multiple of 360 degrees. |
| 123 | + Turtle ScissorPoly 23 90 120 |
| 124 | + .EXAMPLE |
| 125 | + Turtle ScissorPoly 23 60 72 |
| 126 | + .EXAMPLE |
| 127 | + # This can get very chaotic, if it takes a while to reach a multiple of 360 |
| 128 | + # Build N scissor polygons |
| 129 | + foreach ($n in 60..72) { |
| 130 | + Turtle ScissorPoly 16 $n $n |
| 131 | + } |
| 132 | + .EXAMPLE |
| 133 | + Turtle ScissorPoly 16 69 69 |
| 134 | + .EXAMPLE |
| 135 | + # We can draw an outward spiral by growing a bit each step |
| 136 | + turtle StepSpiral |
| 137 | + .EXAMPLE |
| 138 | + turtle StepSpiral 42 120 4 18 |
| 139 | + .EXAMPLE |
| 140 | + turtle @('StepSpiral',3, 120, 'rotate',60 * 6) |
| 141 | + .EXAMPLE |
| 142 | + turtle @('StepSpiral',3, 90, 'rotate',90 * 4) |
| 143 | + .EXAMPLE |
| 144 | + turtle spirolateral |
| 145 | + .EXAMPLE |
| 146 | + turtle spirolateral 50 60 10 |
| 147 | + .EXAMPLE |
| 148 | + turtle spirolateral 50 120 6 @(1,3) |
| 149 | + .EXAMPLE |
| 150 | + turtle spirolateral 23 144 8 |
| 151 | + .EXAMPLE |
| 152 | + turtle spirolateral 23 72 8 |
| 153 | + .EXAMPLE |
| 154 | + turtle @('ArcLeft', 42, 12, 'ArcRight', 72, 60 * 6 ) |
| 155 | + .EXAMPLE |
| 156 | + # Turtle can draw a number of fractals |
| 157 | + turtle BoxFractal 42 4 |
| 158 | + .EXAMPLE |
| 159 | + # We can make a Board Fractal |
| 160 | + turtle BoardFractal 42 4 |
| 161 | + .EXAMPLE |
| 162 | + # We can make a Crystal Fractal |
| 163 | + turtle CrystalFractal 42 4 |
| 164 | + .EXAMPLE |
| 165 | + # We can make ring fractals |
| 166 | + turtle RingFractal 42 4 |
| 167 | + .EXAMPLE |
| 168 | + # We can make a Pentaplexity |
| 169 | + turtle Pentaplexity 42 3 |
| 170 | + .EXAMPLE |
| 171 | + # We can draw the Koch Island |
| 172 | + turtle KochIsland 42 4 |
| 173 | + .EXAMPLE |
| 174 | + # Or we can draw the Koch Curve |
| 175 | + turtle KochCurve 42 |
| 176 | + .EXAMPLE |
| 177 | + # We can make a Koch Snowflake |
| 178 | + turtle KochSnowflake 42 |
| 179 | + .EXAMPLE |
| 180 | + # We can use a Hilbert Curve to fill a space |
| 181 | + Turtle HilbertCurve 42 4 |
| 182 | + .EXAMPLE |
| 183 | + # We can use a Moore Curve to fill a space with a bit more density. |
| 184 | + turtle MooreCurve 42 4 |
| 185 | + .EXAMPLE |
| 186 | + # We can show a binary tree |
| 187 | + turtle BinaryTree 42 4 |
| 188 | + .EXAMPLE |
| 189 | + # We can also mimic plant growth |
| 190 | + turtle FractalPlant 42 4 |
| 191 | + .EXAMPLE |
| 192 | + # The SierpinskiArrowHead Curve is pretty |
| 193 | + turtle SierpinskiArrowheadCurve 42 4 |
| 194 | + .EXAMPLE |
| 195 | + # The SierpinskiTriangle is a Fractal classic |
| 196 | + turtle SierpinskiTriangle 42 4 |
| 197 | + .EXAMPLE |
| 198 | + # We can draw a 'Sierpinski Snowflake' by rotating and drawing multiple Sierpinski Triangles |
| 199 | + turtle @('rotate', 30, 'SierpinskiTriangle',42,4 * 12) |
| 200 | + .EXAMPLE |
| 201 | + turtle @('rotate', 45, 'SierpinskiTriangle',42,4 * 24) |
20 | 202 | #> |
21 | 203 | [CmdletBinding(PositionalBinding=$false)] |
22 | 204 | [Alias('turtle')] |
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