Java Game Dev：如何将平台中两个角色的视图居中？

Question

所以我正在开发这个游戏，现在我在游戏中有两个角色，问题是如果一个角色落后，他就会离开屏幕。当我在屏幕上有一个带有代码行的字符

时，它可以正常工作

centerViewportOnGameObject(sonic, 0.0, 0.0, gameEngine.screenWidth/2.0,
       gameEngine.screenHeight/2.0);"

但是当我在角色上添加第二个角色时优先，并且不在屏幕上。如何解决这个问题的帮助会很好。谢谢。

以下是游戏玩家的代码：

package tutorials.platformTutorial;

import game.assets.*; import game.engine.*;
import game.physics.*; import game.geometry.*;


public class PlatformLayer extends CollisionSpace {

    public static final double GRAVITY_STRENGTH = 800.0;

    public PlatformLayer( GameEngine gameEngine ) {
        super( "PlatformLayer", gameEngine );

        width = 10000;
        height = gameEngine.screenHeight;

        setGravity(0, GRAVITY_STRENGTH );

        addGameObjectCollection( "Platforms" );
        addGameObjectCollection( "Balls" );

        createBackground();
        createPlatforms();
        createCharacter();
        createCharacter2();

    }

    private void createBackground() {
        GameLayer backgroundLayer = 
                new GameLayer( "BackgroundLayer", this.gameEngine );
        backgroundLayer.width = gameEngine.screenWidth;
        backgroundLayer.height = gameEngine.screenHeight;

        GameObject background = new GameObject( backgroundLayer );
        background.setName("Background");
        background.setPosition( backgroundLayer.width/2, backgroundLayer.height/2 );

        ImageAssetRibbon backgroundAsset = (ImageAssetRibbon)assetManager.retrieveGraphicalAsset("Background");
        background.setRealisation(backgroundAsset);
        background.setGeometry( new Box( 0, 0, 1024, 768));

        backgroundLayer.addGameObject(background);
        gameEngine.addGameLayer(backgroundLayer);

        setDrawOrder(backgroundLayer.getDrawOrder() + 1);

    }

    private void createPlatforms() {
        double groundOffset = 0;
        while( groundOffset < this.width ) {
            createPlatform( groundOffset, this.height - assetManager.retrieveGraphicalAssetArchetype
                    ("Platform").height );
            groundOffset += assetManager.retrieveGraphicalAssetArchetype("Platform").width;

      }

        for( int idx = 0; idx < 8; idx++ )
            createPlatform( 300+150 * idx, this.height-50*(idx+1) );
        for( int idx = 0; idx < 8; idx++ )
            createPlatform( 2500-150 * idx, this.height-50*(idx+1) );
        for( int idx = 0; idx < 5; idx++ )
            createPlatform( 3500-400 * idx, this.height-50*(idx+1) );
        for( int idx = 0; idx < 10; idx++ )
            createPlatform( 4500+150 * idx, this.height-50*(idx+1) );
        for( int idx = 0; idx < 12; idx++ )
            createPlatform( 6000, this.height-50*(idx+1) );
        for( int idx = 0; idx < 12; idx++ )
            createPlatform( 7200, this.height-50*(idx+1) );
    }

    private void createPlatform( double x, double y ) {
        Body platform = new Body( this );
        platform.setRealisationAndGeometry("Platform");
        platform.setPosition(x, y);
        platform.setMass( Double.MAX_VALUE );

        addGameObject( platform, "Platforms" );

    }

    private void createCharacter() {
        SonicSprite sonic = new SonicSprite( this );
        sonic.setPosition( 0, gameEngine.screenHeight - sonic.height - 200 );
        addGameObject( sonic );
    }

    private void createCharacter2() {
        SonicSprite2 sonic2 = new SonicSprite2( this );
        sonic2.setPosition(0, gameEngine.screenHeight - sonic2.height - 200);
        addGameObject( sonic2 );
    }

    @Override
    public void update() {
        super.update();

        updateViewPort();
        updateGameObjects();

    }

    private void updateViewPort() {
        GameObject sonic = getGameObject( "Sonic");
        GameObject sonic2 = getGameObject( "Sonic2");




        centerViewportOnGameObject(sonic, 0.0, 0.0, gameEngine.screenWidth/2.0, gameEngine.screenHeight/2.0);
        centerViewportOnGameObject(sonic2, 0.0, 0.0, gameEngine.screenWidth/2.0, gameEngine.screenHeight/2.0);

        GameObject background = gameEngine.getGameObjectFromLayer("Background", "BackgroundLayer");
        ((ImageAssetRibbon)background.getRealisation(0)).setViewPort((int)viewPortLayerX, 0 );
        background.getRealisation(0).update();

    }

  private void updateGameObjects() {
      GameObject sonic = getGameObject( "Sonic" );
      sonic.update();
      GameObject sonic2 = getGameObject( "Sonic2" );
      sonic2.update();

      GameObjectUtilities.reboundIfGameLayerExited(sonic);
      GameObjectUtilities.reboundIfGameLayerExited(sonic2);


  }  

}