b.sc. multimedia computingmultimedia authoring introduction to actionscript 3.0

B.Sc. Multimedia ComputingMultimedia Authoring

Introduction to ActionScript 3.0

Agenda

Simple Types Variables Assignment Boolean Comparisons Control Structures Branching and Looping Introduction to Arrays


Why Learn ActionScript ?

More control over movie clips and their properties Animate elements independently of the timeline Import and export data dynamically Dynamic control of sound and video Create objects that have physics-driven behaviors Personalize the user’s experience


Structure and Syntax

Semicolons ; Curly Braces {} Code Blocks Dot Syntax ( for functions “methods”) Parenthesis Style

Script Spacing and Layout Comments


ActionScript 3.0 Typing

Strict data typing aVariable = 5; // no type given, compiler error aVariable:Number = 5 // declare as being a number type

Case sensitive myValue not the same as myvalue

Class structures for custom objects


Comments // this is a comment on one line

/* these are comments spanning more than one line*/

/* a script to calculate the area of a circle*/var area : Number; // holds the value of the areavar PI : Number = 3.142: // sets the value of PIvar radius :Number = 5 ; // sets the value of PIarea = PI * radius * radius // calculates the area and assigns it to the variable


Semicolons ; and Braces {}

Semicolons separate statementsstatementOne;statementTwo;statementThree;

Curly braces define code blocks{statementOne;stateMentTwostatementThree}


Operators

Binary + - * / Logical AND &&

(5 < 2) && (3 > 1) is False Logical OR ||

(5<2) || (3>1) is True Equalty <, >, <=, >= Assignment

a = 5


Equality ==

a = ‘5’

x = 5

if (a == x) is True

a = 5

x = ‘6’

if (a == x) is False


if statements

if(condition) {

statement(s);}e.g.var firstNumber:int = 25;var secondNumber:int = 39;

if(firstNumber==secondNumber){

trace("Snap!");}


if..else


var firstNumber:int = 25;var secondNumber:int = 39;

if(firstNumber==secondNumber){

trace("Snap!");}

else { trace("Not a match");}

switch


var thisMonth:int = new Date().getMonth(); switch (thisMonth) {

case 0 : trace( "January"); break; case 1 : trace("February"); break; case 2 : trace( "March"); break; default: trace(“Some other month”);} // endSwitch

Looping: while

index = 4;while (index > 0){

// do something hereindex = index -1;// shorthand index --

}


Looping: do while

int:index = 4;do {// do something here

index = index -1;// shorthand index --

} while (index > 0);



Using Arrays in Flash

How to Store Five NumbersUse individual variables for each number stored:

var numberOne:numbervar numberTwo:numbervar numberThree:numbervar numberFour:numbervar numberFive:number

messy - have to process as individual items ratherthan as a collection of grouped items. Solution - use an Array - contiguous data storage


Arrays and Data Storage


15

95

14

70

23

Elements

Size of the array is 5

The value stored at array element number 2 is 14

Array element numbering starts at 0

0

3

2

4

1

Arrays and Data Storage


15

23

14

70

5

Array of numbers (integers)

Gibson

Fender

Punk

Martin

Array of strings

Les Paul

Declaring Arrays in Flash


// create a new array

var numberArray:Array = new Array();

// store the numbers into the array// 15 95 14 70 23

numberArray[0] = 15;numberArray[1] = 95;numberArray[2] = 14;numberArray[3] = 70;numberArray[4] = 23;

Looping through an Array


// total the numbers stored in the number array

var index:Number;var sum:Number;sum = 0;

for (index = 0; index <= 4; index = index + 1){sum = sum + numberArray[index]

}trace("The sum of the numbers in the array is " + sum)

Looping through an Array 2


// total the numbers stored in the number array using array length method

var index:Number;var sum:Number;sum = 0;

for (index = 0; index < numberArray.length; index++){sum = sum + numberArray[index]

}trace("The sum of the numbers in the array is " + sum)

References

ActionScript 3.0 Language Reference Adobe Livedocs


b.sc. multimedia computingmultimedia authoring introduction to actionscript 3.0

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