libgdx学习记录4——舞台Stage

libgdx总的来说是一个框架，而不是一个成熟的游戏引擎。Stage是其中一个比较好的封装，里面自带Camera、SpriteBatch等常用渲染绘图工具。

下面是一个简单的添加图片，并让镜头左右上下移动以显示整副图片的例子。

 package com.fxb.newtest;

 import com.badlogic.gdx.ApplicationAdapter;
 import com.badlogic.gdx.Gdx;
 import com.badlogic.gdx.graphics.GL10;
 import com.badlogic.gdx.graphics.Texture;
 import com.badlogic.gdx.scenes.scene2d.Stage;
 import com.badlogic.gdx.scenes.scene2d.ui.Image;

 public class Lib003_Stage extends ApplicationAdapter{

     Stage stage;
     Image img;
     float leftX = 0;
     float bottomY = 0;

     enum Direct{ move_right, move_left, move_up, move_down };
     Direct direct = Direct.move_right;

     @Override
     public void create() {
         // TODO Auto-generated method stub
         stage = new Stage( Gdx.graphics.getWidth(), Gdx.graphics.getHeight() );
         img = new Image( new Texture( Gdx.files.internal( "data/pal_4.jpg" ) ) );

         img.setPosition(0,0);
         stage.addActor( img );
     }

     @Override
     public void render() {
         // TODO Auto-generated method stub
         Gdx.gl.glClearColor( 1, 1, 1, 1 );
         Gdx.gl.glClear( GL10.GL_COLOR_BUFFER_BIT );

         if(  direct==Direct.move_right ){
             if( leftX + stage.getWidth()<img.getRight() ){
                 stage.getCamera().translate( 2f, 0, 0 );
                 leftX += 2f;
             }
             else{
                 direct = Direct.move_up;
             }
         }
         else if( direct == Direct.move_left ){
             if( leftX > 0 ){
                 stage.getCamera().translate( -2f, 0, 0 );
                 leftX -= 2f;
             }
             else{
                 direct = Direct.move_down;
             }
         }
         else if( direct == Direct.move_up ){
             if( bottomY + stage.getHeight() < img.getTop() ){
                 stage.getCamera().translate( 0, 1.5f, 0 );
                 bottomY += 1.5f;
             }
             else{
                 direct = Direct.move_left;
             }
         }
         else if( direct == Direct.move_down ){
             if( bottomY > 0 ){
                 stage.getCamera().translate( 0, -1.5f, 0 );
                 bottomY -= 1.5f;
             }
             else{
                 direct = Direct.move_right;
             }
         }        

         stage.act();
         stage.draw();
     }

     @Override
     public void dispose() {
         // TODO Auto-generated method stub
         super.dispose();
     }

 }

运行效果：