A turtle graphics (a key feature of the Logo engine written in Swift.

The commands were implemented with reference to the turtle in Python 3 standard libraries.

// Turtle Star!
🐢.beginFill()
36.timesRepeat {
    🐢.forward(200)
    🐢.left(170)
}
🐢.endFill()

// Instantiate a `Tortoise`
let 🐢 = Tortoise()

// Instantiate `ImageCanvas` and add the tortoise
let canvas = ImageCanvas(size: Vec2D(300, 300))
canvas.add(🐢)

// Command 🐢
🐢.right(90)
🐢.forward(100)

// Get drawn `CGImage`
let cgImage = canvas.cgImage

1. Open TortoiseGraphics.xcworkspace in Xcode.
2. Build TortoiseGraphics scheme for iOS Simulator.
3. Select Playground in project navigator.
4. Let's play!

1. Launch Safari on your iPad and browse this page.
2. Tap the following link to subscribe.
   • Subscribe in Swift Playgrounds
3. You can get Tortoise Graphics playground book on Swift Playgrounds app.

1. Download TortoiseGraphics.playgroundbook.zip from here.
2. Unarchive the downloaded zip file.
3. Send the unarchvied TortoiseGraphics.playgroundbook file to your iPad by AirDrop.
4. Open it with Swift Playgrounds app.
5. Let's play!

• Tortoise
• ImageCanvas
• Shape
• Color
• Vec2D

• Speed

• forward(), fd()
• backword(), back(), bk()
• right(), rt()
• left(), lt()
• setPosition(), setPos(), goto()
• setX()
• setY()
• setHeading(), setH()
• home()
• circle()

• position, pos
• towards()
• xcor
• ycor
• heading
• distance()

• penDown(), pd(), down()
• penUp(), pu(), up()
• penSize()
• width()
• isDown
• penSize
• width

• penColor()
• penColor
• fillColor()
• fillColor

• filling
• beginFill()
• endFill()

• reset()
• clear()

• showTortoise(), st()
• hideTortoise(), ht()
• isVisible
• shape()
• shape

• Int.timesRepeat() {}
• random()
• degrees()
• radians()
• colorMode(),
• colorMode

• PlaygroundCanvas
• PlaygroundCanvasLiveView

• SwiftPlaygroundCanvas
• LiveViewController

• Swift 5.1 (Xcode 11.1)
• iOS/iPadOS 13.0 or later

github "temoki/TortoiseGraphics"

pod 'TortoiseGraphics'

• support SVG output
• macOS support
• Swift Package Manager support
• Enrich tortoise commands
• Enrich playground contents

• Special thanks to @kiyoshifuwa, for the amazing art works.

TortoiseGraphics is released under the MIT license. See LICENSE for details.