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Thread: How to change image on key press

  1. #1
    Registered User
    Join Date
    Jun 2014
    Posts
    1

    How to change image on key press

    I have recently made myself a flash snake game, and for the snake head i have made a pacman which opens and closes, but now i need to make it so that if i were to click left, the pacman image turns left, and if i were to click down, it faces down while going down.

    I am new to all of this and can not do it at all, help would be really appreciated!

    Code Below:

    import flash.display.*;
    import flash.events.*;
    import flash.text.*;
    import flash.utils.Timer;
    import flash.geom.Point;
    import flash.display.Stage;

    var score:int;
    score = -10;


    stage.focus=stage; //This is coding to make the arrow keys work on the gamescreen straight away with no clicking

    // constants
    const gridSize:int = 20;
    const leftWall:int =100; //There Dimensions for when the snake dies on the left wall i have changed these to fit around the border of my image and to make it suitable
    const rightWall:int = 580; //Dimensions for when the snake dies on the left wall i have changed these to fit around the border of my image and to make it suitable
    const topWall:int = 75; //Dimensions for when the snake dies on the left wall i have changed these to fit around the border of my image and to make it suitable
    const bottomWall:int = 385; //Dimensions for when the snake dies on the left wall i have changed these to fit around the border of my image and to make it suitable
    const startSpeed:int = 200; //Dimensions for when the snake dies on the left wall i have changed these to fit around the border of my image and to make it suitable
    const startPoint:Point = new Point(260,180);

    // game state
    var gameSprite:Sprite;
    var food:Food = new Food();
    var gameTimer:Timer;
    var snakeParts:Array;

    // snake velocity
    var snakeMoveX:Number = 0;
    var snakeMoveY:Number = 0;
    var nextMoveX:Number = 1;
    var nextMoveY:Number = 0;


    // create game sprite
    gameSprite = new Sprite();
    addChild(gameSprite);

    // create first part of snake
    snakeParts = new Array();
    var firstSnakePart = new SnakeHead(); //I have changed this to make two different parts to the snake so that it fits to my plans of the game
    firstSnakePart.x = startPoint.x;
    firstSnakePart.y = startPoint.y;
    snakeParts.push(firstSnakePart);
    gameSprite.addChild(firstSnakePart);

    // create first food
    gameSprite.addChild(food);
    placeFood();

    // set up listener and timer
    stage.addEventListener(KeyboardEvent.KEY_DOWN,keyD ownFunction);
    gameTimer = new Timer(startSpeed);
    gameTimer.addEventListener(TimerEvent.TIMER,moveSn ake);
    gameTimer.start();


    // register key presses
    function keyDownFunction(event:KeyboardEvent) {
    if (event.keyCode == 37) {
    if (snakeMoveX != 1) {
    nextMoveX = -1;
    nextMoveY = 0;
    }
    } else if (event.keyCode == 39) {
    if (snakeMoveX != -1) {
    nextMoveX = 1;
    nextMoveY = 0;
    }
    } else if (event.keyCode == 38) {
    if (snakeMoveY != 1) {
    nextMoveY = -1;
    nextMoveX = 0;
    }
    } else if (event.keyCode == 40) {
    if (snakeMoveY != -1) {
    nextMoveY = 1;
    nextMoveX = 0;
    }
    }
    }

    // move snake one space in proper direction
    function moveSnake(event:TimerEvent) {
    snakeMoveX = nextMoveX;
    snakeMoveY = nextMoveY;
    var newX:Number = snakeParts[0].x + snakeMoveX*gridSize;
    var newY:Number = snakeParts[0].y + snakeMoveY*gridSize;

    // check for collision
    if ((newX > rightWall) || (newX < leftWall) || (newY > bottomWall) || (newY < topWall)) {
    gameOver();
    } else if (hitTail()) {
    gameOver();
    } else {

    // check for food
    if ((newX == food.x) && (newY == food.y)) { // This is placed into the game to check if any food is on the GameScreen, if there isn't then it will spawn the food.
    placeFood();
    newSnakePart();
    gameTimer.delay -= 2;
    }
    placeTail();
    snakeParts[0].x = newX;
    snakeParts[0].y = newY;
    }
    }

    // randomly place the food
    function placeFood() {

    score = score + 10; //This adds 10 points for every piece of food being picked up
    scoreField.text = score.toString();
    var startPoint: int ;
    startPoint = 80; //This makes the food spawn at least 80 pixels into the stage and around the stage meaning it won't go outside the borders
    var foodX:int = Math.floor(Math.random()* ( rightWall-leftWall)/gridSize)*gridSize + startPoint;
    var foodY:int = Math.floor(Math.random()* ( bottomWall-topWall)/gridSize)*gridSize + startPoint;
    food.x = foodX;
    food.y = foodY;
    }

    // add one sprite to snake
    function newSnakePart() {
    var newPart:SnakePart = new SnakePart();
    gameSprite.addChild(newPart);
    snakeParts.push(newPart);
    var mySound:Sound = new foodSound(); //Adds sound to the game when food spawns and the sound is a mario sound of picking up coins and plays when the food respawns
    mySound.play(); //Just a instruction to make my sound play
    }

    // place all parts of snake
    function placeTail() {
    for(var i:int=snakeParts.length-1;i>0;i--) {
    snakeParts[i].x = snakeParts[i-1].x;
    snakeParts[i].y = snakeParts[i-1].y;
    }
    }

    // see if the head hit any part of the tail
    function hitTail() {
    for(var i:int=1;i<snakeParts.length;i++) {
    if ((snakeParts[0].x == snakeParts[i].x) && (snakeParts[0].y == snakeParts[i].y)) {
    return true;
    }
    }
    return false;
    }

    // stop game
    function gameOver() {
    stage.removeEventListener(KeyboardEvent.KEY_DOWN,k eyDownFunction);
    gotoAndStop (3); //Once the user has died on the game, then this will take them to the end frame which is the third frame
    gameTimer.stop();
    removeChild (gameSprite) ; //This was added so that when the game does restart no food was shown from the previous games and doesn't cause any distractions
    }

  2. #2
    . fruitbeard's Avatar
    Join Date
    Oct 2011
    Posts
    1,785
    Hi,

    Thats some code there and what you require could be pretty lenghty to go through, so try here, it will / should give you an idea http://gregathons.com/2008/06/13/rpg...vement-part-1/

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