libgdx学习记录6——动作Action

libgdx中的Action类能够有效的帮助我们实现位移、旋转、缩放、淡入淡出等效果，对游戏的设计很有用。

Action是一个抽象类，本身不可以实例化。一般使用的它的继承类，常用的有

MoveToAction、MoveByAction、RotateToAction、RotateByAction、ScaleToAction、ScaleByAction、FadeInAction、FadeOutAction等。

如果要定义自己的Acion则需要重写其抽象方法act。

例如：

Action action = new Action(){

　　@Override

　　public void act{

　　stage.getroot().removeActor( this.getActor() );

　　}

}

实例：

 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.Action;
 import com.badlogic.gdx.scenes.scene2d.InputEvent;
 import com.badlogic.gdx.scenes.scene2d.InputListener;
 import com.badlogic.gdx.scenes.scene2d.Stage;
 import com.badlogic.gdx.scenes.scene2d.actions.Actions;
 import com.badlogic.gdx.scenes.scene2d.actions.AlphaAction;
 import com.badlogic.gdx.scenes.scene2d.actions.MoveByAction;
 import com.badlogic.gdx.scenes.scene2d.actions.MoveToAction;
 import com.badlogic.gdx.scenes.scene2d.actions.RotateByAction;
 import com.badlogic.gdx.scenes.scene2d.actions.RotateToAction;
 import com.badlogic.gdx.scenes.scene2d.actions.ScaleByAction;
 import com.badlogic.gdx.scenes.scene2d.actions.ScaleToAction;
 import com.badlogic.gdx.scenes.scene2d.ui.Image;

 public class Lib005_Action extends ApplicationAdapter{

     Stage stage;
     Image img;
     Texture texture;
     Action totalAction;
     Action exitAction;

     @Override
     public void create() {
         // TODO Auto-generated method stub
         stage = new Stage();
         texture = new Texture( Gdx.files.internal( "data/pal4_1.jpg" ) );
         img = new Image( texture );
         img.setSize( texture.getWidth(), texture.getHeight() );
         //img.setPosition( stage.getWidth()/2-img.getWidth()/2, stage.getHeight()/2-img.getHeight()/2 );
         img.setOrigin( img.getWidth()/, img.getHeight()/ );
         stage.addActor( img );

         MoveByAction action1 = Actions.moveBy( stage.getWidth()/-img.getWidth()/, stage.getHeight()/-img.getHeight()/,  );
         ScaleByAction action2 = Actions.scaleBy( , ,  );
         RotateByAction action3 = Actions.rotateBy( -,  );

         RotateToAction action4 = Actions.rotateTo( ,  );
         ScaleToAction action5 = Actions.scaleTo( , ,  );
         MoveToAction action6 = Actions.moveTo( , ,  );        

         totalAction = Actions.forever( Actions.sequence( Actions.sequence(action1, action2, action3), Actions.sequence(action4, action5, action6) ) );
         img.addAction( totalAction );

         AlphaAction action7 = Actions.fadeOut(  );
         AlphaAction action8 = Actions.fadeIn(  );
         Action action9 = new Action(){
             @Override
             public boolean act(float delta) {
                 // TODO Auto-generated method stub
                 stage.getRoot().removeActor( this.getActor() );
                 return false;
             }
         };
         exitAction = Actions.sequence( action7, action8, action9 );

         img.addListener(new InputListener(){
             @Override
             public boolean touchDown(InputEvent event, float x, float y, int pointer, int button) {
                 // TODO Auto-generated method stub
                 img.clearActions();
                 img.addAction( exitAction );
                 return true;
             }
         });

         Gdx.input.setInputProcessor( stage );
     }

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

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

     @Override
     public void dispose() {
         // TODO Auto-generated method stub

         super.dispose();
     }

 }

action一般是添加到Actor中的，当然也可以添加到stage中，使用起来很方便。程序中设计的是一个循环，当点击图片时会清除以前的Action并进行一次淡出淡入后消失。

运行效果：