feat: Turtle.Spirolateral ( Fixes #120 )

Author: StartAutomating

Types/Turtle/Spirolateral.ps1

@@ -0,0 +1,62 @@
+<#
+.SYNOPSIS
+    Draws a spirolateral
+.DESCRIPTION
+    Draws a spirolateral
+.LINK
+    https://en.wikipedia.org/wiki/Spirolateral
+.EXAMPLE
+    turtle spirolateral save ./Spirolateral.svg
+.EXAMPLE
+    turtle spirolateral 50 144 8 save ./Spirolateral-144-8.svg
+.EXAMPLE
+    turtle spirolateral 50 60 10 save ./Spirolateral-60-10.svg
+.EXAMPLE
+    turtle spirolateral 50 120 6 @(1,3) save ./Spirolateral-120-6-1_3.svg
+.EXAMPLE
+    turtle spirolateral 50 90 11 @(3,4,5) save ./Spirolateral-90-11-3_4_5.svg
+#>
+param(
+# The base length of each side (this will be multiplied by the step number)
+[double]
+$Side = 10,
+
+# The angle of the turn
+[double]
+$Angle = 90,
+
+# The step count.
+# This is the number of times the steps will be repeated.
+# This is also the maximum number of iterations the shape will complete.
+[int]
+$StepCount = 10,
+
+# The step numbers that are left turns (counter-clockwise).
+# This allows the creation of general spirolaterals
+[Parameter(ValueFromRemainingArguments)]
+[int[]]
+$LeftTurnSteps
+)
+
+$stepNumber = 1
+$majorStepCount = 0
+do {
+    $null = for ($stepNumber = 1; $stepNumber -le [Math]::Abs($StepCount); $stepNumber++) {
+        $null = $this.Forward($side * $stepNumber)
+        if ($LeftTurnSteps) {
+            if ($LeftTurnSteps -contains $stepNumber) {
+                $this.Left($angle)
+            } else {
+                $this.Right($angle)
+            }
+        } else {
+            $this.Right($angle)
+        }
+    }
+    $majorStepCount++
+} until (
+    (-not ([Math]::Round($this.Heading, 5) % 360 )) -or 
+    $majorStepCount -gt $StepCount
+)
+
+return $this