Starting Out with Alice: A Visual Introduction to Programming

Preface xiiiChapter 1 Introduction to Alice and Objects 11.1 What Is a Computer Program? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.2 Algorithms and Programming Languages . . . . . . . . . . . . . . . . . . . . . . .21.3 Learning to Program with Alice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5TUTORIAL 1-1: Opening and playing an Alice world . . . . . . . . . . . . . . . . . . . . . .61.4 Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131.5 Classes and the Alice Galleries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16TUTORIAL 1-2: Creating a world and adding objects . . . . . . . . . . . . . . . . . . . . .191.6 3D Objects and the Camera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31TUTORIAL 1-3: Moving the camera in 3D space . . . . . . . . . . . . . . . . . . . . . . . .34TUTORIAL 1-4: Manipulating objects in 3D space . . . . . . . . . . . . . . . . . . . . . . .40TUTORIAL 1-5: Manipulating subpart objects . . . . . . . . . . . . . . . . . . . . . . . . . .43Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51Chapter 2 Programming in Alice 572.1 Writing Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57TUTORIAL 2-1: Adding instructions to an Alice world . . . . . . . . . . . . . . . . . . . .62TUTORIAL 2-2: Exploring additional primitive methods . . . . . . . . . . . . . . . . . .672.2 Naming Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .732.3 Designing a Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77TUTORIAL 2-3: Using the program design cycle . . . . . . . . . . . . . . . . . . . . . . . . .822.4 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88TUTORIAL 2-4: Inserting comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .892.5 Tips for Setting Up an Initial Scene . . . . . . . . . . . . . . . . . . . . . . . . . . . .902.6 Executing Instructions Simultaneously . . . . . . . . . . . . . . . . . . . . . . . . .97TUTORIAL 2-5: Creating simultaneously executed instructions . . . . . . . . . . . . .982.7 Exporting Your Code for Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . .1042.8 Exporting an Alice World to Video . . . . . . . . . . . . . . . . . . . . . . . . . . .105Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106Chapter 3 Variables, Functions, Math, and Strings 1133.1 Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113TUTORIAL 3-1: Creating and using a variable . . . . . . . . . . . . . . . . . . . . . . . . .116TUTORIAL 3-2: Creating a set instruction for a variable . . . . . . . . . . . . . . . . .1183.2 Using Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120TUTORIAL 3-3: Calling an ask user function . . . . . . . . . . . . . . . . . . . . . . . . .122TUTORIAL 3-4: Using a proximity function . . . . . . . . . . . . . . . . . . . . . . . . . . .1273.3 Creating Math Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130TUTORIAL 3-5: Using math to avoid collisions . . . . . . . . . . . . . . . . . . . . . . . .1323.4 Working with Strings and Text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138TUTORIAL 3-6: Converting a Number variable to a string . . . . . . . . . . . . . . . .141Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144Chapter 4 Decision and Repetition Structures 1514.1 Boolean Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1514.2 The If/Else Decision Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153TUTORIAL 4-1: Creating an If/Else instruction . . . . . . . . . . . . . . . . . . . . . . .1564.3 Relational Comparisons and Logical Operators . . . . . . . . . . . . . . . . . .163TUTORIAL 4-2: Using a relational operator . . . . . . . . . . . . . . . . . . . . . . . . . . .165TUTORIAL 4-3: Testing an object’s color property . . . . . . . . . . . . . . . . . . . . . .1694.4 The Loop Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .174TUTORIAL 4-4: Using the Loop instruction . . . . . . . . . . . . . . . . . . . . . . . . . . .1754.5 The While Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180TUTORIAL 4-5: Using a While instruction to make an object vanish . . . . . . . .182TUTORIAL 4-6: Using the While instruction to move an object . . . . . . . . . . . .186Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .189Chapter 5 Methods, Functions, and More about Variables 1955.1 Writing Custom Class-Level Methods . . . . . . . . . . . . . . . . . . . . . . . . .195TUTORIAL 5-1: Creating a class-level method . . . . . . . . . . . . . . . . . . . . . . . . .1965.2 Saving an Object to a New Class . . . . . . . . . . . . . . . . . . . . . . . . . . . .199TUTORIAL 5-2: Saving an object to a class . . . . . . . . . . . . . . . . . . . . . . . . . . . .2005.3 Stepwise Refinement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .203TUTORIAL 5-3: Completing the WorkOut world . . . . . . . . . . . . . . . . . . . . . . .2075.4 Passing Arguments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .209TUTORIAL 5-4: Passing arguments to a method . . . . . . . . . . . . . . . . . . . . . . . .2115.5 Using Class-Level Variables as Properties . . . . . . . . . . . . . . . . . . . . . . .215TUTORIAL 5-5: Adding a property to an object . . . . . . . . . . . . . . . . . . . . . . . .2175.6 Writing Class-Level Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .220TUTORIAL 5-6: Writing a class-level function . . . . . . . . . . . . . . . . . . . . . . . . .2215.7 World-Level Methods and Variables . . . . . . . . . . . . . . . . . . . . . . . . . .2265.8 Using Clipboards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2295.9 Tips for Visual Effects and Animation . . . . . . . . . . . . . . . . . . . . . . . . .230Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .241Chapter 6 Events 2496.1 Responding to Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2496.2 Handling Key Press and Mouse Events . . . . . . . . . . . . . . . . . . . . . . . .253TUTORIAL 6-1: Handling key press events . . . . . . . . . . . . . . . . . . . . . . . . . . . .254TUTORIAL 6-2: Handling the while a key is pressed event . . . . . . . . . . .258TUTORIAL 6-3: Handling a mouse click event . . . . . . . . . . . . . . . . . . . . . . . . .2616.3 Using Events in Simulations and Games . . . . . . . . . . . . . . . . . . . . . . .2646.4 Tips for Games and Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . .268Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .275Chapter 7 Lists and Arrays 2817.1 Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .281TUTORIAL 7-1: Creating a list and using the For all in order and For all together instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .285TUTORIAL 7-2: More complex list processing . . . . . . . . . . . . . . . . . . . . . . . . .291TUTORIAL 7-3: Using the Let the mouse move event . . . . . . . .3057.2 Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .308TUTORIAL 7-4: Creating an array and a loop that steps through it . . . . . . . . .311TUTORIAL 7-5: Randomly selecting an array element . . . . . . . . . . . . . . . . . . .317Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .319Chapter 8 Recursion 3238.1 Introduction to Recursion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .323TUTORIAL 8-1: Creating a recursive method . . . . . . . . . . . . . . . . . . . . . . . . . .3278.2 Problem Solving with Recursion . . . . . . . . . . . . . . . . . . . . . . . . . . . . .330TUTORIAL 8-2: Recursive problem solving in animation . . . . . . . . . . . . . . . . .331TUTORIAL 8-3: Writing a recursive mathematical function . . . . . . . . . . . . . . .336Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .338Appendix A Installing Alice 343Appendix B Answers to Checkpoints 347Index 355