topical media & game development
lib-flex-animation-code-04-Game.ax
lib-flex-animation-code-04-Game.ax
(swf
)
[ flash
]
flex
package
{
import flash.display.Sprite;
import flash.display.StageAlign;
import flash.display.StageScaleMode;
import flash.events.Event;
import flash.events.MouseEvent;
public class @ax-lib-flex-animation-code-04-Game extends Sprite
{
private var _cellSize:int = 20;
private var _grid:Grid;
private var _player:Sprite;
private var _index:int;
private var _path:Array;
public function @ax-lib-flex-animation-code-04-Game()
{
stage.align = StageAlign.TOP_LEFT;
stage.scaleMode = StageScaleMode.NO_SCALE;
makePlayer();
makeGrid();
stage.addEventListener(MouseEvent.CLICK, onGridClick);
}
Creates the player sprite. Just a circle here.
private function makePlayer():void
{
_player = new Sprite();
_player.graphics.beginFill(0xff0000);
_player.graphics.drawCircle(0, 0, 5);
_player.graphics.endFill();
_player.x = Math.random() * 600;
_player.y = Math.random() * 600;
addChild(_player);
}
Creates a grid with a bunch of random unwalkable nodes.
private function makeGrid():void
{
_grid = new Grid(30, 30);
for(var i:int = 0; i < 200; i++)
{
_grid.setWalkable(Math.floor(Math.random() * 30),
Math.floor(Math.random() * 30),
false);
}
drawGrid();
}
Draws the given grid, coloring each cell according to its state.
private function drawGrid():void
{
graphics.clear();
for(var i:int = 0; i < _grid.numCols; i++)
{
for(var j:int = 0; j < _grid.numRows; j++)
{
var node:Node = _grid.getNode(i, j);
graphics.lineStyle(0);
graphics.beginFill(getColor(node));
graphics.drawRect(i * _cellSize, j * _cellSize, _cellSize, _cellSize);
}
}
}
Determines the color of a given node based on its state.
private function getColor(node:Node):uint
{
if(!node.walkable) return 0;
if(node == _grid.startNode) return 0xcccccc;
if(node == _grid.endNode) return 0xcccccc;
return 0xffffff;
}
Handles the click event on the GridView. Finds the clicked on cell and toggles its walkable state.
private function onGridClick(event:MouseEvent):void
{
var xpos:int = Math.floor(mouseX / _cellSize);
var ypos:int = Math.floor(mouseY / _cellSize);
_grid.setEndNode(xpos, ypos);
xpos = Math.floor(_player.x / _cellSize);
ypos = Math.floor(_player.y / _cellSize);
_grid.setStartNode(xpos, ypos);
drawGrid();
findPath();
}
Creates an instance of AStar and uses it to find a path.
private function findPath():void
{
var astar:AStar = new AStar();
if(astar.findPath(_grid))
{
_path = astar.path;
_index = 0;
addEventListener(Event.ENTER_FRAME, onEnterFrame);
}
}
Finds the next node on the path and eases to it.
private function onEnterFrame(event:Event):void
{
var targetX:Number = _path [index].x * _cellSize + _cellSize / 2;
var targetY:Number = _path [index].y * _cellSize + _cellSize / 2;
var dx:Number = targetX - _player.x;
var dy:Number = targetY - _player.y;
var dist:Number = Math.sqrt(dx * dx + dy * dy);
if(dist < 1)
{
_index++;
if(_index >= _path.length)
{
removeEventListener(Event.ENTER_FRAME, onEnterFrame);
}
}
else
{
_player.x += dx * .5;
_player.y += dy * .5;
}
}
}
}
(C) Æliens
18/6/2009
You may not copy or print any of this material without explicit permission of the author or the publisher.
In case of other copyright issues, contact the author.
