libgdx游戏引擎开发笔记（九）SuperJumper游戏例子的讲解（篇三）---- 主游戏界面显示框架

在完成前面的基础性工作之后，接下来就到了重头戏：游戏主界面和游戏逻辑的搭建。

1.游戏主界面的搭建

  今天我们要完成的工作是：点击play进入游戏界面，对应的在游戏界面显示一些东西.

效果：

  看到以上四张图相信大家应该很明白要干什么了，下面我们上代码

GameScreen类：

package com.zhf.mylibgdx;
import com.badlogic.gdx.Game;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Screen;
import com.badlogic.gdx.graphics.GL10;
import com.badlogic.gdx.graphics.GLCommon;
import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.math.Rectangle;
import com.badlogic.gdx.math.Vector3;
/**
* 游戏主界面
* @author ZHF
*
*/
public class GameScreen implements Screen {
//状态
static final int GAME_READY = 0 ;   //准备
static final int GAME_RUNNING = 1 ;   //运行
static final int GAME_PAUSED = 2 ;   //暂停
static final int GAME_LEVEL_END = 3 ;   //本关结束
static final int GAME_OVER = 4 ;   //游戏结束

Game game;

int state; //状态
OrthographicCamera guiCam;   //相机
Vector3 touchPoint;   //触点
SpriteBatch batcher;   //用于绘画的

Rectangle pauseBounds;   //暂停按钮
Rectangle resumeBounds; //继续游戏按钮
Rectangle quitBounds;   //离开按钮

int lastScore;   //最后得分
String scoreString;   //显示分数


public GameScreen(Game game) {
this .game = game;
//初始化工作
state = GAME_READY;
guiCam = new OrthographicCamera( 320 , 480 );
guiCam.position.set( 320 / 2 , 480 / 2 , 0 );   //将相机的视角设为中间
touchPoint = new Vector3();
batcher = new SpriteBatch();

pauseBounds = new Rectangle( 320 - 64 , 480 - 64 , 64 , 64 );
resumeBounds = new Rectangle( 160 - 96 , 240 , 192 , 36 );
quitBounds = new Rectangle( 160 - 96 , 240 - 36 , 192 , 36 );

lastScore = 0 ;
scoreString = "SCORE: 0" ;
}

/**刷新状态**/
public void update ( float deltaTime) {
if (deltaTime > 0 .1f) deltaTime = 0 .1f;
//根据游戏动向，刷新状态
switch (state) {
case GAME_READY:
updateReady();   //准备状态
break ;
case GAME_RUNNING:
updateRunning(deltaTime);   //游戏运行状态
break ;
case GAME_PAUSED:
updatePaused();   //游戏暂停状态
break ;
case GAME_LEVEL_END:   //本关结束
updateLevelEnd();
break ;
case GAME_OVER:
updateGameOver();   //游戏结束
break ;
}
}

/**准备状态**/
private void updateReady () {
if (Gdx.input.justTouched()) {
state = GAME_RUNNING;
}
}
/**游戏运行状态**/
private void updateRunning ( float deltaTime) {
if (Gdx.input.justTouched()) {
guiCam.unproject(touchPoint.set(Gdx.input.getX(), Gdx.input.getY(), 0 ));
//点击暂停
if (OverlapTester.pointInRectangle(pauseBounds, touchPoint.x, touchPoint.y)) {
Assets.playSound(Assets.clickSound);
state = GAME_PAUSED;
return ;
}
}
}
/**游戏暂停状态**/
private void updatePaused () {
if (Gdx.input.justTouched()) {
guiCam.unproject(touchPoint.set(Gdx.input.getX(), Gdx.input.getY(), 0 ));
//点击继续游戏
if (OverlapTester.pointInRectangle(resumeBounds, touchPoint.x, touchPoint.y)) {
Assets.playSound(Assets.clickSound);
state = GAME_RUNNING;
return ;
}
//点击离开，返回到主菜单界面
if (OverlapTester.pointInRectangle(quitBounds, touchPoint.x, touchPoint.y)) {
Assets.playSound(Assets.clickSound);
game.setScreen( new MainMenuScreen(game));
return ;
}
}
}
/**本关结束**/
private void updateLevelEnd () {
if (Gdx.input.justTouched()) {
state = GAME_READY;
}
}
/**游戏结束**/
private void updateGameOver () {
if (Gdx.input.justTouched()) {
game.setScreen( new MainMenuScreen(game));
}
}

/**绘画**/
public void draw ( float deltaTime) {
GLCommon gl = Gdx.gl;
gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
gl.glClearColor(0f, 0f, 0f, 0f);
guiCam.update();
batcher.setProjectionMatrix(guiCam.combined);
batcher.enableBlending();

batcher.begin();
//根据游戏状态刷新界面
switch (state) {
case GAME_READY:
presentReady();   //绘制准备界面
break ;
case GAME_RUNNING:
presentRunning();   //绘制暂停和分数显示
break ;
case GAME_PAUSED:
presentPaused();   //绘制暂停菜单和分数显示
break ;
case GAME_LEVEL_END:
presentLevelEnd();   //绘制本关结束
break ;
case GAME_OVER:
presentGameOver();   //绘制游戏结束
break ;
}
batcher.end();
}

/**绘制准备**/
private void presentReady () {
batcher.draw(Assets.ready, 160 - 192 / 2 , 240 - 32 / 2 , 192 , 32 );
}
/**绘制暂停和分数显示**/
private void presentRunning () {
batcher.draw(Assets.pause, 320 - 64 , 480 - 64 , 64 , 64 );
Assets.font.draw(batcher, scoreString, 16 , 480 - 20 );
}
/**绘制暂停菜单和分数显示**/
private void presentPaused () {
batcher.draw(Assets.pauseMenu, 160 - 192 / 2 , 240 - 96 / 2 , 192 , 96 );
Assets.font.draw(batcher, scoreString, 16 , 480 - 20 );
}
/**绘制本关结束**/
private void presentLevelEnd () {
String topText = "the princess is ..." ;
String bottomText = "in another castle!" ;
float topWidth = Assets.font.getBounds(topText).width;
float bottomWidth = Assets.font.getBounds(bottomText).width;
Assets.font.draw(batcher, topText, 160 - topWidth / 2 , 480 - 40 );
Assets.font.draw(batcher, bottomText, 160 - bottomWidth / 2 , 40 );
}
/**绘制游戏结束**/
private void presentGameOver () {
batcher.draw(Assets.gameOver, 160 - 160 / 2 , 240 - 96 / 2 , 160 , 96 );
float scoreWidth = Assets.font.getBounds(scoreString).width;
Assets.font.draw(batcher, scoreString, 160 - scoreWidth / 2 , 480 - 20 );
}
@Override
public void render( float delta) {
update(delta);
draw(delta);
}
@Override
public void resize( int width, int height) {
// TODO Auto-generated method stub
}
@Override
public void show() {
// TODO Auto-generated method stub
}
@Override
public void hide() {
// TODO Auto-generated method stub
}
@Override
public void pause() {
if (state == GAME_RUNNING) state = GAME_PAUSED;
}
@Override
public void resume() {
// TODO Auto-generated method stub
}
@Override
public void dispose() {
// TODO Auto-generated method stub
}
}

分析：

      这里代码里的注释已经写得很清楚，这里我再讲一下框架，方便初学者学习，在构造方法里我们初始化了一些变量，接下来很重要的一步就是在render()方法里写了两个重要的方法：update() 和 draw(); 即：游戏的逻辑

update(float deltaTime): 根据游戏动向不断地刷新状态（准备状态、游戏运行状态、游戏暂停状态、本关结束、本关结束）

draw(float deltaTime): 根据游戏状态刷新界面（

                      presentReady();  //绘制准备界面

presentRunning();  //绘制暂停和分数显示

presentPaused(); //绘制暂停菜单和分数显示

presentLevelEnd(); //绘制本关结束

presentGameOver(); //绘制游戏结束  ）

我们别忘了和前面一样，在MainMneuScreen中将条状那行注释去掉：

game.setScreen( new GameScreen(game));

同样，游戏界面中包含一些元素（如暂停按钮，菜单等），自然要在Asset类中对应的加载资源进去。

声明：

//游戏界面
public static TextureRegion pause; //暂停按钮
public static TextureRegion pauseMenu;   //暂停弹出菜单
public static TextureRegion ready;   //准备
public static TextureRegion gameOver; //游戏结束

实例化：

//游戏界面界面
pause = new TextureRegion(items, 64 , 64 , 64 , 64 );
pauseMenu = new TextureRegion(items, 224 , 128 , 192 , 96 );
ready = new TextureRegion(items, 320 , 224 , 192 , 32 );
gameOver = new TextureRegion(items, 352 , 256 , 160 , 96 );

ok！这一讲可能代码比较少，这里我们主要先将框架搭建起来，下一讲我们我涉及到游戏场景中各个元素以及世界的编写。

源码下载：http://down.51cto.com/data/894874