(libgdx小结)背景移动(1)

滚屏原理

其实滚屏的原理很简单，我们所玩的雷电类游戏，简单的游戏使用1张游戏背景，比较复杂的游戏，就需要使用多张游戏背景，当然也可以使用比较长的游戏背景图片，但是他们的原理是相同的。我们拿本次的例子作为实验讲解。

（1）首先，将第一张背景图片底部平铺到整个屏幕（可以仅是X周铺满，不必缩放）。

（2）其次，将第二章背景图片的底部，紧接在第一张图片上面。

（3）如果直接连接不和谐，可以适当的加点像素（如：+ 111）。

（4）当第一张背景图片的Y坐标超出屏幕并且超出长度和自己高度等高，那么这是立即将该图片的Y坐标设置到第二张图片的上方。

（5）最后，当第二张背景图片的Y坐标超出屏幕并且超出长度和自己高度等高，那么这是立即将该图片的Y坐标设置到第一张图片的上方。

（6）当然了，我们要使用的背景图片，必须要可以无缝的衔接，否则会影响用户体验。我们使用的2张图片就是无缝连接的，为了方便大家区分，这里i我的2个图片都标记了号码。

二、应用举例

MyGame

package com.example.groupactiontest;

import com.badlogic.gdx.Game;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.audio.Music;

public class MyGame extends Game {

Music music;
StartScreen startScreen;
GameScreen gameScreen;

@Override
public void create() {
startScreen = new StartScreen(this);
gameScreen = new GameScreen(this);

music = Gdx.audio.newMusic(Gdx.files.internal("plane.ogg"));
music.play();
music.setLooping(true);
music.setVolume(15f);

this.setScreen(startScreen);

}

}


StartScreen

package com.example.groupactiontest;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.graphics.Texture;
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.ui.Image;

public class StartScreen implements Screen {

MyGame game;

Image logoImage;
Image bgImage;

Stage stage;

public StartScreen(MyGame game) {
this.game = game;
}

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

}

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

}

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

}

@Override
public void render(float arg0) {
Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

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

@Override
public void resize(int arg0, int arg1) {
// TODO Auto-generated method stub

}

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

}

@Override
public void show() {
stage = new Stage();

Texture logoTexture = new Texture(Gdx.files.internal("logo.png"));
Texture bgTexture = new Texture(Gdx.files.internal("background.png"));

logoImage = new Image(logoTexture);
logoImage.setPosition(240-(logoTexture.getWidth()/2), 400);

bgImage = new Image(bgTexture);
bgImage.setSize(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());

logoImage.addListener(new InputListener(){
@Override
public boolean touchDown(InputEvent event, float x, float y,
int pointer, int button) {

game.setScreen(game.gameScreen);

stage.clear();

return true;
}
});

stage.addActor(bgImage);
stage.addActor(logoImage);

Gdx.input.setInputProcessor(stage);

}

}


GameScreen

package com.example.groupactiontest;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.graphics.Texture;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.graphics.g2d.TextureRegion;

public class GameScreen implements Screen {

MyGame game;

//以下变量用来处理背景移动逻辑
Texture bgTexture1;
Texture bgTexture2;

TextureRegion bgTextureRegion1;
TextureRegion bgTextureRegion2;

SpriteBatch batch;

float bg1x,bg1y,bg2x,bg2y;

//以下逻辑用来处理飞机移动逻辑
float beginTouchedX,beginTouchedY,endTouchedX,endTouchedY;
Texture planeTexture;
float touchedX,touchedY;

public GameScreen(MyGame game) {
this.game = game;
}

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

}

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

}

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

}

@Override
public void render(float arg0) {
Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

logic();

touch();

batch.begin();

//其实这个时候bg1x和bg2x一直都为0
batch.draw(bgTextureRegion1, bg1x, bg1y, 480, 852);
batch.draw(bgTextureRegion2, bg2x, bg2y, 480, 852);

batch.draw(planeTexture, 120 + touchedX, touchedY,120,120);//touchedX之所以要加120是为了矫正位置
// batch.draw(planeTexture, beginTouchedX, beginTouchedY,120,120);
batch.end();
}

@Override
public void resize(int arg0, int arg1) {
// TODO Auto-generated method stub

}

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

}

@Override
public void show() {
batch = new SpriteBatch();

bgTexture1 = new Texture(Gdx.files.internal("background1.png"));
bgTexture2 = new Texture(Gdx.files.internal("background2.png"));

bgTextureRegion1 = new TextureRegion(bgTexture1,0,0,480,852);
bgTextureRegion2 = new TextureRegion(bgTexture2,0,0,480,852);

bg1x = bg2x = 0;
bg1y = 0;
bg2y = bg1y + bgTextureRegion1.getRegionHeight();

planeTexture = new Texture(Gdx.files.internal("plane.png"));

}

/**
* 背景移动
*/
public void logic(){
bg1y -= 3;
bg2y -= 3;

float RH1 = bgTextureRegion1.getRegionHeight();
float RH2 = bgTextureRegion2.getRegionHeight();

if(bg1y < -RH1){
bg1y = bg2y + bgTextureRegion2.getRegionHeight();
}

if(bg2y < -RH2){
bg2y = bg1y + bgTextureRegion1.getRegionHeight();
}
}

/**
* 移动飞机
*/
public void touch(){

if(Gdx.input.justTouched()){
beginTouchedX = Gdx.input.getX(0);
beginTouchedY = Gdx.input.getY(0);
}

if(Gdx.input.isTouched()){
endTouchedX = Gdx.input.getX(0);
endTouchedY = Gdx.input.getY(0);
}

touchedX = endTouchedX - beginTouchedX;
touchedY = -(endTouchedY - beginTouchedY);//这里要取反。否则上下划的时候运动会相反
}
}


三、效果图



四、源码下载
http://download.csdn.net/detail/caihongshijie6/7010971