Introduction to Logo Turtle

LogoTurtle is currently the FIRST and only one Chrome Extension for Turtle Graphics. I have also written a PHP version of Logo Interpreter in 2006 but that runs only on the server.

Previous Contributions

• v0.0.7: Turtle Programming v0.0.7: Functions with Parameters + Recursion!
• v0.0.6: Turtle Programming v0.0.6: Adding Circle, MoveTo, Turn and Screen!
• v0.0.5: Turtle Programming v0.0.5: Adding IF/ELSE and STOP!
• v0.0.4: LogoTurtle: Make Variables and Comments
• v0.0.3: Turtle Graphics Programming Update: Adding text, jump, dot, fontsize, download as png
• v0.0.2: LogoTurtle v0.0.2: ShowTurtle, HideTurtle, Color, Width and Help.
• Teach Your Kids Programming - The First Logo Interpreter (Turtle Graphics) in Chrome Extension!
  v0.0.1

v0.0.8 New Features

Along with bug fixes and code tweaks, This Commit has added the support of the following features:

1. Ignore Multi-line comments /* */ pairs like other high-level modern programming languages.
2. dotxy takes two parameters that allow you to place a dot without moving the turtle anywhere.
3. js that allows you to run the javascript code that handles the canvas directly!.

Screenshots

Classic Logo, Source code:

# Spiral 
/*
  draw a spiral
*/
cs
to spiral :size :angle
  if (:size>:T) [stop] ; size too big
  forward :size
  right :angle
  spiral :size+2 :angle 
end 
spiral 1 91 ; call the function

Drawing a line using dotxy

cs width 2 make "x 1 make "y 1
repeat 80 [
  dotxy :x :y 
  make "x :x+1 
  make "y :y+1
]

You can control the Turtle using Javascript via JS

cs js [
  for (let i = 0; i < 5; i ++ ) {
   this.logo.fd(100);
   this.logo.rt(144);
  }
]

Javascript Parser to Skip Comments, Whitespaces and New Lines

    // jump comments and white spaces
    skipTo(s, i, U) {
        // skip for white spaces and newlines
        while ((i < U) && (isSpace(s[i]) || s[i] == '\n')) {
            i ++;               
        }
        if (i >= U) { // reach block end
            return i;
        }
        // skip comments till the end
        if ((s[i] == ';') || (s[i] == '#')) {
            i ++;
            while ((i < U) && (s[i] != '\n')) {
                i ++;
            }
            i ++;
        }
        // skip // comments
        if (i + 1 < U) {
            if ((s[i] == '/') && (s[i + 1] == '/')) {
                i += 2;
                while ((i < U) && (s[i] != '\n')) {
                    i ++;
                }
                i ++;
            }
        }
        // skip /* */ comments
        if (i + 1 < U) {
            if ((s[i] == '/') && (s[i + 1] == '*')) {
                i += 2;
                while ((i < U) && ((s[i] != '*') || (s[i + 1] != '/'))) {
                    i ++;
                }
                i += 2;             
            }
        }       
        return i;   
    }

Roadmap of Chrome Extension: Logo Turtle

1. Add Functions
2. Add IF/THEN/ELSE
3. Add Variables
4. Add Colors
5. Add MoveTo
6. Add PrintText
7. Add Circle
8. Add Arc
9. Add Eraser
10. Add Fill
11. Save As Picture
12. Save As Program
13. Comments
14. Add Recursion Support
15. Add Global/Local Scopes
16. Sleep
17. etc. etc.

Technology Stack

If an App can be written in Javascript, eventually it will be written in Javascript.

Chrome Webstore

Install the Turtle Programming for Kids Now!

Contribution Welcome

Github: https://github.com/DoctorLai/LogoTurtle

1. Fork it!
2. Create your feature branch: git checkout -b my-new-feature
3. Commit your changes: git commit -am 'Add some feature'
4. Push to the branch: git push origin my-new-feature
5. Submit a pull request.

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Posted on Utopian.io - Rewarding Open Source Contributors

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