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# ARTDM 170, Week10: Arrays + Using Randomization

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### ARTDM 170, Week10: Arrays + Using Randomization

1. 1. ARTDM 170, Week 10: Arrays and Math <ul><li>Gilbert Guerrero [email_address] gilbertguerrero.com/blog/artdm-170 </li></ul>
2. 2. Arrays
3. 3. What is an Array? <ul><li>Arrays group data together in a single element </li></ul><ul><li>Can be thought of as a variable that stores variables var arrayName :Array = new Array(); </li></ul>
4. 4. Storing and Retrieving <ul><li>Arrays can be used to store data var fruits :Array = new Array(); fruits = [“apples”,“oranges”,“bananas”]; </li></ul><ul><li>Data can be retrieved from arrays using the index numbers trace( fruits[0] ); //apples trace( fruits[1] ); //oranges trace( fruits[2] ); //bananas // I like to eat apples and oranges. trace( &quot; I like to eat &quot;+ fruits[0] +&quot; and &quot;+ fruits[1] +&quot; . &quot; ); </li></ul>
5. 5. Arrays and Objects <ul><li>Arrays can be used to store objects var redBall :Ball = new Ball(); var orangeBall :Ball = new Ball(); var yellowBall :Ball = new Ball(); var ballArray :Array = new Array(); ballArray = [redBall, orangeBall, yellowBall]; </li></ul>
6. 6. Arrays and Objects <ul><li>Instead of using the variable names for each ball, we can use the array ballArray = [redBall, orangeBall, yellowBall]; ballArray [0].x = 100; ballArray [0].y = 100; ballArray [1].x = 200; ballArray [1].y = 100; ballArray [2].x = 300; ballArray [2].y = 100; </li></ul>
7. 7. for() loops <ul><li>for() statement allows you to repeat an operation a certain number of times </li></ul><ul><ul><li>for(var i:int=0; i < N; i++) { trace(i); } </li></ul></ul><ul><li>If N=3, then output would display: </li></ul><ul><ul><li>0 1 2 </li></ul></ul><ul><li>The script runs while i is less than N, but not greater than or equal to it </li></ul>
8. 8. Using arrays and for loops <ul><li>In the case of our ballArray, we could use a for() statement instead of typing out every line </li></ul><ul><li>for(var i:int=0; i < 3; i++) { ballArray[ i ].x = 100*( i +1); ballArray[ i ].y = 100; } </li></ul><ul><li>The above code would set all the y values to 100. The x values would be 100, 200, and 300. </li></ul>
9. 9. Creating multiples with arrays <ul><li>We can use a for() loop to create and add the balls to an array </li></ul><ul><ul><li>var ballArray :Array = new Array(); for(var i:int=0; i < 300; i++) { var thisBall :Ball = new Ball(); ballArray.push( thisBall ); ballArray[ i ].x = 50*( i +1); ballArray[ i ].y = 100; } </li></ul></ul><ul><li>In this case we can create hundreds with a few lines of code </li></ul>
10. 10. Randomization <ul><li>Generate a random number between 0 and .999999 </li></ul><ul><li>Math.random() </li></ul><ul><li>Round down using Math.floor and multiply Math.random by a number to get a random integer between zero and your number </li></ul><ul><li>//generates integers from 0 to 29 </li></ul><ul><li>Math.floor(Math.random()*30) </li></ul>
11. 11. Randomizing location and velocity <ul><li>Combining for() loops, arrays, and random numbers we can create hundreds of objects and give each one a different location and velocity </li></ul><ul><li>for(var i:int=0; i < 300; i++) { var thisBall :Ball = new Ball(); ballArray.push( thisBall ); ballArray[ i ].x = Math.floor(Math.random()*400); ballArray[ i ].y = Math.floor(Math.random()*500); ballArray[ i ].moveX = Math.floor(Math.random()*20); ballArray[ i ].moveY = Math.floor(Math.random()*20); } </li></ul>
12. 12. Array Functions <ul><li>Add an item to the end of the array fruits.push(“strawberries”); </li></ul><ul><li>Remove an item from the middle of an array fruits.slice(5,1); </li></ul><ul><li>More array functions: Chapter 5 in AS 3.0 Cookbook </li></ul>
13. 13. Open Flash <ul><li>Create a new ActionScript 3.0 document: MyAnimation.fla </li></ul><ul><li>Create a new ActionScript file: MyAnimation.as </li></ul>
14. 14. Script package { import flash.display.*; import flash.events.*; public class MyAnimation extends MovieClip { // Setup the values private var bounce:Number = -0.9; private var gravity:Number = .5; private var oldX:Number; private var oldY:Number; private var N:uint = 3; private var ballArray:Array = new Array(); //Constructor public function MyAnimation() { init(); } //Methods public function init():void { for (var i:uint = 0; i < N; i++){ var thisBall:Ball = new Ball(); ballArray.push(thisBall); ballArray[i].graphics.lineStyle(5,0x000000); ballArray[i].graphics.beginFill(0xCCCCCC); ballArray[i].graphics.drawCircle(0,0,25); ballArray[i].x = Math.floor(Math.random()*500); ballArray[i].y = Math.floor(Math.random()*400); ballArray[i].moveX = Math.floor(Math.random()*20); ballArray[i].moveY = Math.floor(Math.random()*20); addChild(ballArray[i]); } addEventListener(Event.ENTER_FRAME, onMoveCircle); } public function onMoveCircle(pEvent:Event):void { for (var i:int = 0; i < ballArray.length; i++){ ballArray[i].moveY = ballArray[i].moveY + gravity; ballArray[i].x = ballArray[i].x + ballArray[i].moveX; ballArray[i].y = ballArray[i].y + ballArray[i].moveY; if(ballArray[i].x > stage.stageWidth - ballArray[i].width/2 || ballArray[i].x < ballArray[i].width/2) { ballArray[i].moveX = ballArray[i].moveX*bounce; //change direction } if(ballArray[i].y > stage.stageHeight - ballArray[i].height/2 || ballArray[i].y < ballArray[i].height/2) { ballArray[i].moveY = ballArray[i].moveY*bounce; //change direction } } } } }
15. 15. Homework, due Oct 21 <ul><li>Follow along and complete the Flash Memory Game tutorial </li></ul><ul><li>See you next week! </li></ul>