[libgdx游戏开发教程]使用Libgdx进行游戏开发(2)-游戏框架搭建

让我们抛开理论开始code吧。

入口类CanyonBunnyMain的代码：

package com.packtpub.libgdx.canyonbunny;

import com.badlogic.gdx.ApplicationListener;
import com.packtpub.libgdx.canyonbunny.game.WorldController;
import com.packtpub.libgdx.canyonbunny.game.WorldRenderer;

public class CanyonBunnyMain implements ApplicationListener {
    private static final String TAG = CanyonBunnyMain.class.getName();
    private WorldController worldController;
    private WorldRenderer worldRenderer;

    @Override
    public void create() {
    }

    @Override
    public void render() {
    }

    @Override
    public void resize(int width, int height) {
    }

    @Override
    public void pause() {
    }

    @Override
    public void resume() {
    }

    @Override
    public void dispose() {
    }
}

WorldController

package com.packtpub.libgdx.canyonbunny.game;

public class WorldController {
    private static final String TAG = WorldController.class.getName();

    public WorldController() {
    }

    private void init() {
    }

    public void update(float deltaTime) {
    }
}

WorldRenderer

package com.packtpub.libgdx.canyonbunny.game;

import com.badlogic.gdx.graphics.OrthographicCamera;
import com.badlogic.gdx.graphics.g2d.SpriteBatch;
import com.badlogic.gdx.utils.Disposable;
import com.packtpub.libgdx.canyonbunny.util.Constants;

public class WorldRenderer implements Disposable {
    private OrthographicCamera camera;
    private SpriteBatch batch;
    private WorldController worldController;

    public WorldRenderer(WorldController worldController) {
    }

    private void init() {
    }

    public void render() {
    }

    public void resize(int width, int height) {
    }

    @Override
    public void dispose() {
    }
}

我们完成了CanyonBunnyMain, WorldController, WorldRenderer的第一个基本版本（骨架）。

有必要回顾一下我们框架的核心点：游戏主循环是在CanyonBunnyMain类的render()方法中。

要把三者联系起来，首先在create()中添加：

@Override
    public void create() {
        // Set Libgdx log level to DEBUG
        Gdx.app.setLogLevel(Application.LOG_DEBUG);
        // Initialize controller and renderer
        worldController = new WorldController();
        worldRenderer = new WorldRenderer(worldController);
    }

然后在render里调用

    @Override
    public void render() {
        // Update game world by the time that has passed
        // since last rendered frame.
        worldController.update(Gdx.graphics.getDeltaTime());
        // Sets the clear screen color to: Cornflower Blue
        Gdx.gl.glClearColor(0x64 / 255.0f, 0x95 / 255.0f, 0xed / 255.0f,0xff / 255.0f);
//or Gdx.gl.glClearColor(100/255.0f, 149/255.0f, 237/255.0f, 255/255.0f);自定义的颜色
        // Clears the screen
        Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
        // Render game world to screen
        worldRenderer.render();
    }

顺便修改下resize():（在游戏开始和改变窗口大小的时候会触发）

    @Override
    public void resize(int width, int height) {
        worldRenderer.resize(width, height);
    }

之后是dispose

@Override
public void dispose() {
worldRenderer.dispose();
}

【在Android下，可以做个小改进】

在Android上进行暂停的时候：我们让游戏别渲染了。

 加个标志位

private boolean paused;

create()和render()这么改：

    @Override
    public void create() {
        // Set Libgdx log level to DEBUG
        Gdx.app.setLogLevel(Application.LOG_DEBUG);
        // Initialize controller and renderer
        worldController = new WorldController();
        worldRenderer = new WorldRenderer(worldController);
        // Game world is active on start
        paused = false;
    }

    @Override
    public void render() {
        // Do not update game world when paused.
        if (!paused) {
            // Update game world by the time that has passed
            // since last rendered frame.
            worldController.update(Gdx.graphics.getDeltaTime());
        }
        // Sets the clear screen color to: Cornflower Blue
        Gdx.gl.glClearColor(0x64 / 255.0f, 0x95 / 255.0f, 0xed / 255.0f,
                0xff / 255.0f);
        // Clears the screen
        Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
        // Render game world to screen
        worldRenderer.render();
    }

加上切换的代码：

    @Override
    public void pause() {
        paused = true;
    }

    @Override
    public void resume() {
        paused = false;
    }

OK。整合在一起了。运行看看效果。

太棒了。（你应该猜到了这里使用的设计模式就是MVC模式）

接下来，我们需要一个常量类来保存所有用到的常量。

Constants.java

package com.packtpub.libgdx.canyonbunny.util;
public class Constants {
// Visible game world is 5 meters wide
public static final float VIEWPORT_WIDTH = 5.0f;
// Visible game world is 5 meters tall
public static final float VIEWPORT_HEIGHT = 5.0f;
}

现在需要在屏幕上加点东东了。我们现在在屏幕上画5个箱子。有人已经开始在准备箱子的图片了，这里我们不用图片，自己画。

（画一个矩形填上色，画两个对角线，再画个矩形边框，不就是个箱子吗？哈哈）像素画是不会美工的程序员的最爱，除了比较简单，还因为可以用程序画出来。

当然，用图片也是一样的。
首先要在脑子里想清楚，箱子对象归谁管理？画箱子这个职责是谁的？

箱子对象自然是由控制器来管理：为了方便识别，我们让其中一个箱子作为当前选中的箱子，并且让它自转。

　　public Sprite[] testSprites;
    public int selectedSprite;

    public WorldController() {
        init();
    }

    private void init() {
        initTestObjects();
    }

    private void initTestObjects() {
        // Create new array for 5 sprites
        testSprites = new Sprite[5];
        // Create empty POT-sized Pixmap with 8 bit RGBA pixel data
        int width = 32;
        int height = 32;
        Pixmap pixmap = createProceduralPixmap(width, height);
        // Create a new texture from pixmap data
        Texture texture = new Texture(pixmap);
        // Create new sprites using the just created texture
        for (int i = 0; i < testSprites.length; i++) {
            Sprite spr = new Sprite(texture);
            // Define sprite size to be 1m x 1m in game world
            spr.setSize(1, 1);
            // Set origin to sprite's center
            spr.setOrigin(spr.getWidth() / 2.0f, spr.getHeight() / 2.0f);
            // Calculate random position for sprite
            float randomX = MathUtils.random(-2.0f, 2.0f);
            float randomY = MathUtils.random(-2.0f, 2.0f);
            spr.setPosition(randomX, randomY);
            // Put new sprite into array
            testSprites[i] = spr;
        }
        // Set first sprite as selected one
        selectedSprite = 0;
    }

    private Pixmap createProceduralPixmap(int width, int height) {
        Pixmap pixmap = new Pixmap(width, height, Format.RGBA8888);
        // Fill square with red color at 50% opacity
        pixmap.setColor(1, 0, 0, 0.5f);
        pixmap.fill();
        // Draw a yellow-colored X shape on square
        pixmap.setColor(1, 1, 0, 1);
        pixmap.drawLine(0, 0, width, height);
        pixmap.drawLine(width, 0, 0, height);
        // Draw a cyan-colored border around square
        pixmap.setColor(0, 1, 1, 1);
        pixmap.drawRectangle(0, 0, width, height);
        return pixmap;
    }

    public void update(float deltaTime) {
        updateTestObjects(deltaTime);
    }

    private void updateTestObjects(float deltaTime) {
        // Get current rotation from selected sprite
        float rotation = testSprites[selectedSprite].getRotation();
        // Rotate sprite by 90 degrees per second
        rotation += 90 * deltaTime;
        // Wrap around at 360 degrees
        rotation %= 360;
        // Set new rotation value to selected sprite
        testSprites[selectedSprite].setRotation(rotation);
    }

注意：这里并没有任何涉及画箱子的部分(这里只是用代码生成了一副像素画，还没有显示)。不要和render搞混淆了。
接下来WorldRender负责把它画出来。

public WorldRenderer(WorldController worldController) {
        this.worldController = worldController;
        init();
    }

    private void init() {
        batch = new SpriteBatch();
        camera = new OrthographicCamera(Constants.VIEWPORT_WIDTH,
                Constants.VIEWPORT_HEIGHT);
        camera.position.set(0, 0, 0);
        camera.update();
    }

    public void render() {
        renderTestObjects();
    }

    private void renderTestObjects() {
        batch.setProjectionMatrix(camera.combined);
        batch.begin();
        for (Sprite sprite : worldController.testSprites) {
            sprite.draw(batch);
        }
        batch.end();
    }

    public void resize(int width, int height) {
        camera.viewportWidth = (Constants.VIEWPORT_HEIGHT / height) * width;
        camera.update();
    }

    @Override
    public void dispose() {
        batch.dispose();
    }

看看效果

 至此，MVC模式的基本框架完成了。

接下来，我们需要开发一些Debug的控制功能来方便我们的开发。

比如

按上下左右，当前选中的箱子就开始上下左右移动。

按R键，游戏场景重新初始化。

按空格键，下一个箱子被选中。

再比如摄像机跟随当前箱子,视角放大缩小。

不用急着看下一章的代码实现，自己先试试用代码实现这些功能。