视差背景和引擎

Question

I'm new to game development andengine. I want to add ParallaxBackground but I don't know how to change background on player move. I'm using arrow for moving a player. Now my question is where I write the code parallaxBackground.setParallaxValue(5); I was written this line in onAreaTouched method of arrow but it not work. please help me. Thanks.

Code

private Camera mCamera;
private static  int CAMERA_WIDTH = 800;
private static  int CAMERA_HEIGHT = 480;

private BitmapTextureAtlas bgTexture;
private ITextureRegion bgTextureRegion;

@Override
protected void onCreateResources() {

    BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");
    bgTexture = new BitmapTextureAtlas(getTextureManager(),2160,480,TextureOptions.REPEATING_BILINEAR);
    bgTextureRegion = BitmapTextureAtlasTextureRegionFactory.createFromAsset(bgTexture, this, "background.png", 0, 0);
    bgTexture.load(); 
}
@Override
protected Scene onCreateScene() {

    this.getEngine().registerUpdateHandler(new FPSLogger());

    Scene scene = new Scene();
    scene.setBackground(new Background(Color.BLACK));

    final ParallaxBackground parallaxBackground = new ParallaxBackground(0, 0, 0);
    final VertexBufferObjectManager vertexBufferObjectManager = this.getVertexBufferObjectManager();

    parallaxBackground.attachParallaxEntity(new ParallaxEntity(0.0f, new Sprite(0, CAMERA_HEIGHT - this.bgTextureRegion.getHeight(), this.bgTextureRegion, vertexBufferObjectManager)));
    scene.setBackground(parallaxBackground);

Robot robot = new Robot();

    // add Player
    final AnimatedSprite animatedRobotSprite = new AnimatedSprite(robot.centerX, robot.centerY, 122, 126, (ITiledTextureRegion) robotTextureRegion, getVertexBufferObjectManager());
    scene.attachChild(animatedRobotSprite);
    animatedRobotSprite.animate(new long[]{1250,50,50});


    // add right arrow button
    Sprite rightArrowSprite = new Sprite(0, CAMERA_HEIGHT-70, rightArrowTextureRegion, getVertexBufferObjectManager()){

        @Override
        public boolean onAreaTouched(TouchEvent pSceneTouchEvent,float pTouchAreaLocalX, float pTouchAreaLocalY) {

            switch (pSceneTouchEvent.getAction()) {

            case TouchEvent.ACTION_DOWN:
                moveRight = true;
                parallaxBackground.setParallaxValue(5);
                break;

            case TouchEvent.ACTION_MOVE:
                moveRight = true;
                break;

            case TouchEvent.ACTION_UP:
                moveRight = false;
                break;

            default:
                break;
            }
            return super.onAreaTouched(pSceneTouchEvent, pTouchAreaLocalX, pTouchAreaLocalY);
        }
    };
    scene.attachChild(rightArrowSprite);

    scene.registerTouchArea(rightArrowSprite);

    scene.setTouchAreaBindingOnActionDownEnabled(true);

    scene.setTouchAreaBindingOnActionMoveEnabled(true);

    scene.registerUpdateHandler(new IUpdateHandler() {

        @Override
        public void reset() {

        }

        @Override
        public void onUpdate(float pSecondsElapsed) {

            if ( moveRight ){
                animatedRobotSprite.setPosition(animatedRobotSprite.getX()+speedX, animatedRobotSprite.getY());


            }
        }
    });

    return scene;
}

Answer 1

I see at least on possible problem: You have only one ParallaxEntity attached. The visual effect of parallax is created by multiple entities moving at different speeds. But I think what you are seeing is that your background is not scrolling. If you do not use the AutoParallaxBackground class, you have to update the paralax amount on each update.

Inside the autoparallax class, this is what it does onUpdate():

@Override
    public void onUpdate(final float pSecondsElapsed) {
        super.onUpdate(pSecondsElapsed);

        this.mParallaxValue += this.mParallaxChangePerSecond * pSecondsElapsed;
    }

Looking at this you can see that the setParallaxValue() is an absolute number, so to make it continually scroll, you will need to feed it a new number on each update. For example, in you main game update loop, you could feed in your player.getX() into parallaxBackground.setParallaxValue() like so:

parallaxBackground.setParallaxValue(rightArrowSprite.getX());

While this may not be the exact effect you want, you should now see the background moving when your character moves.

Answer 2

There are different modifiers foe updating your entity(AnimatedSprite) you can use them for movement like

final Entity playerEntity = ...;//Get player entity here.

final float jumpDuration = 2;
final float x= playerEntity.getX();



final MoveXModifiermoveModifier = new MoveXModifier(jumpDuration / 2, x+ 100, y);


playerEntity.registerEntityModifier(moveModifier );

Answer 3

It's not necessary to have two background moving at different speeds. With one fixed background and one "moving" background you will notice the effect when the player moves. However, I've tried setting an absolute value in

parallaxBackground.setParallaxValue(10f);

And the effect was not continuous. What it worked for me was a recipe found in Android Cookbook which is based on overriding the onUpdate of the background to change only when the camera has moved.

 ParallaxBackground background = new ParallaxBackground(0.3f, 0.3f,0.9f) {
 /* We'll use these values to calculate the parallax value of the background*/

 float cameraPreviousX = 0;
 float parallaxValueOffset = 0;

 /* onUpdates to the background, we need to calculate new
 * parallax values in order to apply movement to the background
 * objects (the hills in this case) */

  @Override

public void onUpdate(float pSecondsElapsed) {

 /* Obtain the camera's current center X value */
 final float cameraCurrentX = mCamera.getCenterX();

 /* If the camera's position has changed since last update... */
 if (cameraPreviousX != cameraCurrentX) {

 /* Calculate the new parallax value offset by subtracting the previous update's camera x coordinate from the current update's camera x coordinate */
  parallaxValueOffset += cameraCurrentX - cameraPreviousX;

  /* Apply the parallax value offset to the background, which will in-turn offset the positions of entities attached to the background */
  this.setParallaxValue(parallaxValueOffset);

  /* Update the previous camera X since we're finished with this update */
  cameraPreviousX = cameraCurrentX;

 }
 super.onUpdate(pSecondsElapsed);

 }
};

background.attachParallaxEntity(new ParallaxEntity(5, hillFurthest));

Note than depending on the camera configuration, the "5" value included in the "attachParallaxEntity" may need to be negative. Otherwise, the background will move in the opposite direction of the player.