u/Leading_Bandicoot358

Just liked the simple design

A while back I finally figured out how to make Turtle Graphics in PowerShell.

I wrote a pretty fun module for it, Turtle. At this point there's a silly amount of stuff you can do with this, including infinite art generation and data visualizations.

The topic came up again today, and so I thought I'd take a quick second to show the secrets of the ooze to the community.

Here's an example of a really minimal Turtle. All it does is: .Rotate() by an angle, Move .Forward() a distance, and let us change if the pen is down with .PenDown.

#Define our custom object 
$turtle = [PSCustomObject]@{
    Heading = 0.0
    Steps = @()
    PenDown = $true
}

#Add a Rotate and Forward method, and a PathData script property
$turtle | 
    Add-Member ScriptMethod Rotate {
        param([double]$Angle)
        # Turn by the angle
        $this.Heading += $angle
        # and return ourself.
        return $this
    } -Force -PassThru |
    Add-Member ScriptMethod Forward {
        param([double]$Distance)
        #Any move of the turtle is just a polar coordinate.
        #We turn the Distance@Heading into x,y with some trig
        $x = $Distance * [math]::cos($this.Heading * [Math]::PI / 180)
        $y = $Distance * [math]::sin($this.Heading * [Math]::PI / 180)
        #If the pen is down, we draw a relative line (`l`)
        #If the pen is up, we move (`m`)
        $letter = if ($this.PenDown) { "l" } else {"m" }
        #Add the step
        $this.Steps += "$letter $x $y"
        #Return ourselves.
        return $this
    } -Force -PassThru |
    Add-Member ScriptProperty PathData {
        return "m 0 0 $($this.Steps)"
    }        
        
# Make a basic triangle 
$turtle.
    Forward(42).Rotate(120).
    Forward(42).Rotate(120).
    Forward(42).Rotate(120)

# Put our path data into an XML
$svg = [xml]"<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 42 42' width='100%' height='100%'>
    <path d='$($turtle.PathData)' />
</svg>"

$svg.Save("$pwd/triangle.svg")

That's ~40 lines for a simple Turtle Graphics engine (with docs)!

Of course, we can make our Turtle much smarter by adding more and more moves. All we need to do is add more and more methods. That's what the module gives us: a pretty smart Turtle with lots of methods and properties. Play around, it's fun!

Turtle Graphics are pretty great! Hopefully this helps make it clear to everyone how simple and easy they can be.