Turtle Programming v0.0.6: Adding Circle, MoveTo, Turn and Screen!

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

• v0.0.5: 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.
• v0.0.1: Teach Your Kids Programming – The First Logo Interpreter (Turtle Graphics) in Chrome Extension!

Turtle Graphics v0.0.6 New Features

This Commit has the following changes:

• Add MoveTo function
• Add Circle function
• Add Turning (absolute degree)
• Set Screen Color
• Enhanced Error/Warning handling

LogoTurtle Screenshots

Let’s put all the above in one LOGO source code to demonstrate:

ht cs screen green color yellow ; test comment
pu moveto -200 20 pd turn 270
repeat 8 [circle 50 fd 10 rt 45]

logo-turtle-circle-screen-color

Javascript Parses Logo Source Code with 2 Parameters

The MoveTo takes two parameters that moves the turtle to a given coordinate, which is handled by the following javascript.

case "moveto":
    expr = this.evalVars(word_next);
    try {
        word_next = eval(expr);
    } catch (e) {
        this.pushErr(word, LOGO_ERR_EVAL, expr);
        return false;
    }               
    if ((word_next == '') || (!isNumeric(word_next))) {
        this.pushErr(word, LOGO_ERR_MISSING_NUMBERS, word_next);
        return false;
    }
    second_word = getNextWord(s, y.next, U);
    second_word_word = second_word.word;
    expr = this.evalVars(second_word_word);
    try {
        second_word_word = eval(expr);
    } catch (e) {
        this.pushErr(word, LOGO_ERR_EVAL, expr);
        return false;
    }                       
    if ((second_word_word == '') || (!isNumeric(second_word_word))) {
        this.pushErr(word, LOGO_ERR_MISSING_NUMBERS, second_word_word);
        return false;
    }                   
    this.logo.moveTo(word_next, second_word_word);
    i = second_word.next;
    break;  

Roadmap of Chrome Extension: Logo Turtle

• Add Functions
• Add IF/THEN/ELSE
• Add Variables
• Add Colors
• Add MoveTo
• Add PrintText
• Add Circle
• Add Arc
• Add Eraser
• Add Fill
• Save As Picture
• Save As Program
• Comments
• Add Recursion Support
• Add Global/Local Scopes
• 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

• Fork it!
• Create your feature branch: git checkout -b my-new-feature
• Commit your changes: git commit -am ‘Add some feature’
• Push to the branch: git push origin my-new-feature
• Submit a pull request.

–EOF (The Ultimate Computing & Technology Blog) —