topical media & game development
#graphic-flex-image-effects-06-Flex-PointAtTest.ax
#graphic-flex-image-effects-06-Flex-PointAtTest.ax
[swf]
[flash]
flex
package {
import flash.display.Shape;
import flash.display.Sprite;
import flash.events.KeyboardEvent;
import flash.geom.Matrix3D;
import flash.geom.Vector3D;
import flash.ui.Keyboard;
[SWF(width=800, height=600, backgroundColor=0x000000)]
Class demonstrates how Matrix3D's pointAt() can be used to orient a sprite
towards another sprite. Here, a ball is added to the stage and its movements on all
three axes are controlled by the user through the keyboard. An arrow is placed in the
center of the stage and is updated to always point at the ball.
public class @ax-graphic-flex-image-effects-06-Flex-PointAtTest extends Sprite {
private static const MOVE_RATE:uint = 15;
protected var _ball:Shape;
protected var _pointer:Shape;
Constructor. Creates the necessary sprites and sets up listener for
keyboard activity.
public function @ax-graphic-flex-image-effects-06-Flex-PointAtTest() {
createPointer();
createBall();
updatePointer();
stage.addEventListener(KeyboardEvent.KEY_DOWN, onStageKeyDown);
}
Creates the ball shape that the user will control.
private function createBall():void {
_ball = new Shape();
_ball.graphics.beginFill(0xFFFFFF);
_ball.graphics.drawCircle(0, 0, 20);
_ball.graphics.endFill();
// places the ball offcenter so pointer can point at it
_ball.x = stage.stageWidth/2 + 100;
_ball.y = stage.stageHeight/2 - 100;
addChild(_ball);
}
Creates pointer shape.
private function createPointer():void {
_pointer = new Shape();
_pointer.graphics.beginFill(0xFF0000);
_pointer.graphics.moveTo(-40, -40);
_pointer.graphics.lineTo(40, 0);
_pointer.graphics.lineTo(-40, 40);
_pointer.graphics.lineTo(0, 0);
_pointer.graphics.lineTo(-40, -40);
_pointer.graphics.endFill();
// centers pointer
_pointer.x = stage.stageWidth/2;
_pointer.y = stage.stageHeight/2;
// assigning to z creates Matrix3D on transform of _pointer
_pointer.z = 0;
addChild(_pointer);
}
Updates the pointer, rotating it to point at the current ball position.
protected function updatePointer():void {
var ballPosition:Vector3D = new Vector3D(_ball.x, _ball.y, _ball.z);
_pointer.transform.matrix3D.pointAt(
ballPosition,
Vector3D.X_AXIS,
new Vector3D(0, -1, 0)
);
}
Handles keyboard events. This updated ball position based on keyboard activity.
parameter: event Event dispatched by Stage.
private function onStageKeyDown(event:KeyboardEvent):void {
switch (event.keyCode) {
case Keyboard.UP:
// if SHIFT is used, alter position on z axis
if (event.shiftKey) {
_ball.z -= MOVE_RATE;
// otherwise alter position on y axis
} else {
_ball.y -= MOVE_RATE;
}
break;
case Keyboard.DOWN:
// if SHIFT is used, alter position on z axis
if (event.shiftKey) {
_ball.z += MOVE_RATE;
// otherwise alter position on y axis
} else {
_ball.y += MOVE_RATE;
}
break;
case Keyboard.RIGHT:
_ball.x += MOVE_RATE;
break;
case Keyboard.LEFT:
_ball.x -= MOVE_RATE;
break;
}
// point pointer at current ball position
updatePointer();
event.updateAfterEvent();
}
}
}
(C) Æliens
04/09/2009
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.
