8、示例5：TestPong

1 示例5：TestPong

这是一个类似于弹球的游戏，开始让画面动起来了。效果图如下：

按数字键1、2或9、0分别移动两个绿色的弹板，球碰到板子或四周的墙壁就会反弹。

1.1 源代码

源代码

```
package jmetest.TutorialGuide;
```
```
import com.jme.app.SimpleGame;
```
```
import com.jme.bounding.BoundingBox;
```

import com.jme.bounding.BoundingSphere;

import com.jme.input.KeyBindingManager;

```
import com.jme.input.KeyInput;
```
```
import com.jme.math.FastMath;
```
```
import com.jme.math.Vector3f;
```
```
import com.jme.renderer.ColorRGBA;
```
```
import com.jme.renderer.Renderer;
```
```
import com.jme.scene.Node;
```
```
import com.jme.scene.Spatial;
```
```
import com.jme.scene.Text;
```
```
import com.jme.scene.shape.Box;
```
```
import com.jme.scene.shape.Sphere;
```

import com.jme.scene.state.MaterialState;

import com.jme.scene.state.MaterialState.ColorMaterial;

```
/**
```
```
 * TestPong
```
```
 */
```

public class TestPong extends SimpleGame {

```
    // Side walls and goal detectors
```
```
    private Node sideWalls;
```
```
    private Box player1GoalWall;
```
```
    private Box player2GoalWall;
```
```
    // Ball
```
```
    private Sphere ball;
```
```
    private Vector3f ballVelocity;
```
```
    // Player 1
```
```
    private Box player1;
```

    private float player1Speed = 100.0f;

```
    private int player1Score = 0;
```
```
    private Text player1ScoreText;
```
```
    // Player 2
```
```
    private Box player2;
```

    private float player2Speed = 100.0f;

```
    private int player2Score = 0;
```
```
    private Text player2ScoreText;
```

    public static void main(String[] args) {

```
        TestPong app = new TestPong();
```

        app.setConfigShowMode(ConfigShowMode.AlwaysShow);

```
        app.start();
```
```
    }
```
```
    protected void simpleUpdate() {
```
```
        // Player 1 movement
```

        if (KeyBindingManager.getKeyBindingManager().isValidCommand("PLAYER1_MOVE_UP", true)) {

            player1.getLocalTranslation().z -= player1Speed* timer.getTimePerFrame();

```
        }
```

        if (KeyBindingManager.getKeyBindingManager().isValidCommand("PLAYER1_MOVE_DOWN", true)) {

            player1.getLocalTranslation().z += player1Speed* timer.getTimePerFrame();

```
        }
```

        player1.getLocalTranslation().z = FastMath.clamp(player1.getLocalTranslation().z, -38, 38);

```
        // Player 2 movement
```

        if (KeyBindingManager.getKeyBindingManager().isValidCommand("PLAYER2_MOVE_UP", true)) {

            player2.getLocalTranslation().z -= player2Speed* timer.getTimePerFrame();

```
        }
```

        if (KeyBindingManager.getKeyBindingManager().isValidCommand("PLAYER2_MOVE_DOWN", true)) {

            player2.getLocalTranslation().z += player2Speed* timer.getTimePerFrame();

```
        }
```

        player2.getLocalTranslation().z = FastMath.clamp(player2.getLocalTranslation().z, -38, 38);

```
        // Collision with player pads
```

        if (player1.hasCollision(ball, false) || player2.hasCollision(ball, false)) {

```
            ballVelocity.x *= -1f;
```
```
        }
```
```
        // Collision with side walls
```

        if (sideWalls.hasCollision(ball, false)) {

```
            ballVelocity.z *= -1f;
```
```
        }
```

        // Checking for goals (ie collision with back walls)

        if (player1GoalWall.hasCollision(ball, false)) {

            System.out.println("1 撞);

```
            player1Score++;
```

            player1ScoreText.getText().replace(0, player1ScoreText.getText().length(), "" + player1Score);

            ball.getLocalTranslation().set(0,0,0);

        } else if (player2GoalWall.hasCollision(ball, false)) {

            System.out.println("2 撞);

```
            player2Score++;
```

            player2ScoreText.getText().replace(0, player2ScoreText.getText().length(), "" + player2Score);

            ball.getLocalTranslation().set(0,0,0);

```
        }
```

        // Move ball according to velocity

        ball.getLocalTranslation().addLocal(ballVelocity.mult(timer.getTimePerFrame()));

```
    }
```
```
    protected void simpleInitGame() {
```

        display.setTitle("jME - Pong");

```
        // Initialize camera
```

        cam.setFrustumPerspective(45.0f, (float) display.getWidth()

                / (float) display.getHeight(), 1f, 1000f);

        cam.setLocation(new Vector3f(-150, 200, 80));

        cam.lookAt(new Vector3f(-30, 0, 10), Vector3f.UNIT_Y);

```
        cam.update();
```
```
        // Create ball
```

        ball = new Sphere("Ball", 8, 8, 2);

        ball.setModelBound(new BoundingSphere());

```
        ball.updateModelBound();
```

        ball.setDefaultColor(ColorRGBA.blue);

```
        rootNode.attachChild(ball);
```
```
        // Initialize ball velocity
```

        ballVelocity = new Vector3f(100f, 0f, 50f);

```
        // Create Player 1 pad
```

        player1 = new Box("Player1", new Vector3f(), 2, 5, 10);

        player1.setModelBound(new BoundingBox());

```
        player1.updateModelBound();
```

        player1.getLocalTranslation().set(-100, 0, 0);

        player1.setDefaultColor(ColorRGBA.green);

```
        rootNode.attachChild(player1);
```
```
        // Create Player 2 pad
```

        player2 = new Box("Player2", new Vector3f(), 2, 5, 10);

        player2.setModelBound(new BoundingBox());

```
        player2.updateModelBound();
```

        player2.getLocalTranslation().set(100, 0, 0);

        player2.setDefaultColor(ColorRGBA.green);

```
        rootNode.attachChild(player2);
```
```
        // Create side walls
```
```
        sideWalls = new Node("Walls");
```

        rootNode.attachChild(sideWalls);

        Box wall = new Box("Wall1", new Vector3f(), 112, 2, 2);

        wall.setModelBound(new BoundingBox());

```
        wall.updateModelBound();
```

        wall.getLocalTranslation().set(0, 0, 50);

```
        sideWalls.attachChild(wall);
```

        wall = new Box("Wall2", new Vector3f(), 112, 2, 2);

        wall.setModelBound(new BoundingBox());

```
        wall.updateModelBound();
```

        wall.getLocalTranslation().set(0, 0, -50);

```
        sideWalls.attachChild(wall);
```

        // Create back wall, goal detector for player 1

        player1GoalWall = new Box("player1GoalWall", new Vector3f(), 2, 2, 50);

        player1GoalWall.setModelBound(new BoundingBox());

        player1GoalWall.updateModelBound();

        player1GoalWall.getLocalTranslation().set(110, 0, 0);

        rootNode.attachChild(player1GoalWall);

        // Create back wall, goal detector for player 2

        player2GoalWall = new Box("player2GoalWall", new Vector3f(), 2, 2, 50);

        player2GoalWall.setModelBound(new BoundingBox());

        player2GoalWall.updateModelBound();

        player2GoalWall.getLocalTranslation().set(-110, 0, 0);

        rootNode.attachChild(player2GoalWall);

```
        // Assign key bindings
```

        KeyBindingManager.getKeyBindingManager().set("PLAYER1_MOVE_UP", KeyInput.KEY_1);

        KeyBindingManager.getKeyBindingManager().set("PLAYER1_MOVE_DOWN", KeyInput.KEY_2);

        KeyBindingManager.getKeyBindingManager().set("PLAYER2_MOVE_UP", KeyInput.KEY_9);

        KeyBindingManager.getKeyBindingManager().set("PLAYER2_MOVE_DOWN", KeyInput.KEY_0);

```
        // Create score showing items
```

        player1ScoreText = Text.createDefaultTextLabel("player1ScoreText", "0");

        player1ScoreText.setRenderQueueMode(Renderer.QUEUE_ORTHO);

        player1ScoreText.setLightCombineMode(Spatial.LightCombineMode.Off);

        player1ScoreText.setLocalTranslation(new Vector3f(0, display.getHeight()/2, 1));

        rootNode.attachChild(player1ScoreText);

        player2ScoreText = Text.createDefaultTextLabel("player2ScoreText", "0");

        player2ScoreText.setRenderQueueMode(Renderer.QUEUE_ORTHO);

        player2ScoreText.setLightCombineMode(Spatial.LightCombineMode.Off);

        player2ScoreText.setLocalTranslation(new Vector3f(display.getWidth() - 30, display.getHeight()/2, 1));

        rootNode.attachChild(player2ScoreText);

        // Make the object default colors shine through

        MaterialState ms = display.getRenderer().createMaterialState();

        ms.setColorMaterial(ColorMaterial.AmbientAndDiffuse);

```
        rootNode.setRenderState(ms);
```
```
    }
```
```
}
```

1.2 详细说明

// Initialize camera

cam.setFrustumPerspective(45.0f, (float) display.getWidth()

/ (float) display.getHeight(), 1f, 1000f);

cam.setLocation(new Vector3f(-150, 200, 80));

cam.lookAt(new Vector3f(-30, 0, 10), Vector3f.UNIT_Y);

cam.update();

首先初始化摄像头的角度，让我们从上到下看有一个很好的视角。如果不设置cam效果是怎样呢：

按w、a、s、d、q、z等按键调整一下角度再看：

要想调个好视角还得费一番功夫，上图的视角也很不理想。

后面一段分别定义了弹球及其速度、绿色弹板（player1和player2）、两边的围墙（wall、sideWalls）、和后墙（两个玩家的目标探测仪goal detector）。这里的wall绑定到sideWalls节点上。

下面来看看怎么让画面动起来。

我们需要重载simpleUpdate函数。因为在main函数中调用app.start()启动游戏，start函数里面有个while循环，一刻不停地更新状态。 update(-1.0f);这个update是在BaseSimpleGame类里实现的，它调用了 simpleUpdate。所以要想小球动起来，只需要在simpleUpdate中修改它的位置坐标即可，让它产生一定规律的运动。

// Move ball according to velocity

ball.getLocalTranslation().addLocal(

ballVelocity.mult(timer.getTimePerFrame()));

这就让小球延一个方向跑过去。ballVelocity是个速度向量，它乘以一个标量仍然是个向量。如果要使用ball.getLocalTranslation().add，产生的新的向量并没有赋给ball的localTranslation，所以用add小球不动。

下面来看看碰撞检测的方法，用hasCollision函数即可：

if (ball.hasCollision(sideWalls, false)) {

System.out.println("撞上侧墙了");

}

撞上之后需要改变小球的运动方向（向量），可以参考光线反射原理：

if (ball.hasCollision(sideWalls, false)) {

ballVelocity.z *= -1f;

}

if (KeyBindingManager.getKeyBindingManager().isValidCommand(

"PLAYER1_MOVE_UP", true)) {

player1.getLocalTranslation().z -= player1Speed

* timer.getTimePerFrame();

}

这是移动挡板，只需修改位置向量即可。没有限制的话挡板就会移到围墙外面去。

player1.getLocalTranslation().z = FastMath.clamp(player1.getLocalTranslation().z, -38, 38);

就限制了z的移动范围。函数FastMath.clamp的源代码如下：

public static float clamp(float input, float min, float max) {

return (input < min) ? min : (input > max) ? max : input;

}

如果给定的input值小于min，则返回min；如果大于max，就返回max；如果在min和max之间就返回input自己。这样我们就把一个数组固定在某个范围之内了。

现在我们基本上把这个例子弄清楚了：要想使一个物体运动只需在重载函数simpleUpdate中修改位置向量即可。可以通过hasCollision函数检测两个物体是否发生碰撞。

我在调试的时候遇到一个问题：如果小球的速度向量设置不合理，有可能检测不到碰撞，这时小球会飞出界外。比如：ballVelocity = new Vector3f(100f, 0f, 50f);时就从后挡板飞出去了，ballVelocity = new Vector3f(50f, 0f, 50f);就能在围墙内自由弹跳。我想可能是jME时钟造成的，运动的两个位置跳跃过大使之检测不到碰撞。比如我把速率调小：ballVelocity.mult((float) 0.1)又能在范围内弹跳了。

posted on 2009-09-26 14:29 飞飞狐阅读(276) 评论(0) 编辑收藏举报

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