Question

如何在没有重力的情况下保持所有碰撞和加速效果。我想添加一个不会落到地面的物体，但如果没有碰撞附加物保持其位置。

public class PhysicsMouseJointExample extends SimpleBaseGameActivity implements IAccelerationListener, IOnSceneTouchListener, IOnAreaTouchListener {
    // ===========================================================
    // Constants
    // ===========================================================

    private static final int CAMERA_WIDTH = 720;
    private static final int CAMERA_HEIGHT = 480;

    private static final FixtureDef FIXTURE_DEF = PhysicsFactory.createFixtureDef(1, 0.5f, 0.5f);

    // ===========================================================
    // Fields
    // ===========================================================

    private BitmapTextureAtlas mBitmapTextureAtlas;

    private TiledTextureRegion mBoxFaceTextureRegion;
    private TiledTextureRegion mCircleFaceTextureRegion;

    private Scene mScene;

    private PhysicsWorld mPhysicsWorld;
    private int mFaceCount = 0;

    private MouseJoint mMouseJointActive;
    private Body mGroundBody;

    // ===========================================================
    // Constructors
    // ===========================================================

    // ===========================================================
    // Getter & Setter
    // ===========================================================

    // ===========================================================
    // Methods for/from SuperClass/Interfaces
    // ===========================================================

    @Override
    public EngineOptions onCreateEngineOptions() {
        Toast.makeText(this, "Touch the screen to add objects.", Toast.LENGTH_LONG).show();

        final Camera camera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);

        return new EngineOptions(true, ScreenOrientation.LANDSCAPE_FIXED, new RatioResolutionPolicy(CAMERA_WIDTH, CAMERA_HEIGHT), camera);
    }

    @Override
    public void onCreateResources() {
        BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/");

        this.mBitmapTextureAtlas = new BitmapTextureAtlas(this.getTextureManager(), 64, 64, TextureOptions.BILINEAR);
        this.mBoxFaceTextureRegion = BitmapTextureAtlasTextureRegionFactory.createTiledFromAsset(this.mBitmapTextureAtlas, this, "face_box_tiled.png", 0, 0, 2, 1); // 64x32
        this.mCircleFaceTextureRegion = BitmapTextureAtlasTextureRegionFactory.createTiledFromAsset(this.mBitmapTextureAtlas, this, "face_circle_tiled.png", 0, 32, 2, 1); // 64x32
        this.mBitmapTextureAtlas.load();
    }

    @Override
    public Scene onCreateScene() {
        this.mEngine.registerUpdateHandler(new FPSLogger());

        this.mScene = new Scene();
        this.mScene.setBackground(new Background(0, 0, 0));
        this.mScene.setOnSceneTouchListener(this);
        this.mScene.setOnAreaTouchListener(this);

        this.mPhysicsWorld = new PhysicsWorld(new Vector2(0, SensorManager.GRAVITY_EARTH), false);
        this.mGroundBody = this.mPhysicsWorld.createBody(new BodyDef());

        final VertexBufferObjectManager vertexBufferObjectManager = this.getVertexBufferObjectManager();
        final Rectangle ground = new Rectangle(0, CAMERA_HEIGHT - 2, CAMERA_WIDTH, 2, vertexBufferObjectManager);
        final Rectangle roof = new Rectangle(0, 0, CAMERA_WIDTH, 2, vertexBufferObjectManager);
        final Rectangle left = new Rectangle(0, 0, 2, CAMERA_HEIGHT, vertexBufferObjectManager);
        final Rectangle right = new Rectangle(CAMERA_WIDTH - 2, 0, 2, CAMERA_HEIGHT, vertexBufferObjectManager);

        final FixtureDef wallFixtureDef = PhysicsFactory.createFixtureDef(0, 0.5f, 0.5f);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, ground, BodyType.StaticBody, wallFixtureDef);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, roof, BodyType.StaticBody, wallFixtureDef);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, left, BodyType.StaticBody, wallFixtureDef);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, right, BodyType.StaticBody, wallFixtureDef);

        this.mScene.attachChild(ground);
        this.mScene.attachChild(roof);
        this.mScene.attachChild(left);
        this.mScene.attachChild(right);

        this.mScene.registerUpdateHandler(this.mPhysicsWorld);

        return this.mScene;
    }

    @Override
    public void onGameCreated() {
        this.mEngine.enableVibrator(this);
    }

    @Override
    public boolean onSceneTouchEvent(final Scene pScene, final TouchEvent pSceneTouchEvent) {
        if(this.mPhysicsWorld != null) {
            switch(pSceneTouchEvent.getAction()) {
                case TouchEvent.ACTION_DOWN:
                    this.addFace(pSceneTouchEvent.getX(), pSceneTouchEvent.getY());
                    return true;
                case TouchEvent.ACTION_MOVE:
                    if(this.mMouseJointActive != null) {
                        final Vector2 vec = Vector2Pool.obtain(pSceneTouchEvent.getX() / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT, pSceneTouchEvent.getY() / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT);
                        this.mMouseJointActive.setTarget(vec);
                        Vector2Pool.recycle(vec);
                    }
                    return true;
                case TouchEvent.ACTION_UP:
                    if(this.mMouseJointActive != null) {
                        this.mPhysicsWorld.destroyJoint(this.mMouseJointActive);
                        this.mMouseJointActive = null;
                    }
                    return true;
            }
            return false;
        }
        return false;
    }

    @Override
    public boolean onAreaTouched(final TouchEvent pSceneTouchEvent, final ITouchArea pTouchArea, final float pTouchAreaLocalX, final float pTouchAreaLocalY) {
        if(pSceneTouchEvent.isActionDown()) {
            final IAreaShape face = (IAreaShape) pTouchArea;
            /*
             * If we have a active MouseJoint, we are just moving it around
             * instead of creating a second one.
             */
            if(this.mMouseJointActive == null) {
                this.mEngine.vibrate(100);
                this.mMouseJointActive = this.createMouseJoint(face, pTouchAreaLocalX, pTouchAreaLocalY);
            }
            return true;
        }
        return false;
    }

    @Override
    public void onAccelerationAccuracyChanged(final AccelerationData pAccelerationData) {

    }

    @Override
    public void onAccelerationChanged(final AccelerationData pAccelerationData) {
        final Vector2 gravity = Vector2Pool.obtain(pAccelerationData.getX(), pAccelerationData.getY());
        this.mPhysicsWorld.setGravity(gravity);
        Vector2Pool.recycle(gravity);
    }

    @Override
    public void onResumeGame() {
        super.onResumeGame();

        this.enableAccelerationSensor(this);
    }

    @Override
    public void onPauseGame() {
        super.onPauseGame();

        this.disableAccelerationSensor();
    }

    // ===========================================================
    // Methods
    // ===========================================================

    public MouseJoint createMouseJoint(final IAreaShape pFace, final float pTouchAreaLocalX, final float pTouchAreaLocalY) {
        final Body body = (Body) pFace.getUserData();
        final MouseJointDef mouseJointDef = new MouseJointDef();

        final Vector2 localPoint = Vector2Pool.obtain((pTouchAreaLocalX - pFace.getWidth() * 0.5f) / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT, (pTouchAreaLocalY - pFace.getHeight() * 0.5f) / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT);
        this.mGroundBody.setTransform(localPoint, 0);

        mouseJointDef.bodyA = this.mGroundBody;
        mouseJointDef.bodyB = body;
        mouseJointDef.dampingRatio = 0.95f;
        mouseJointDef.frequencyHz = 30;
        mouseJointDef.maxForce = (200.0f * body.getMass());
        mouseJointDef.collideConnected = true;

        mouseJointDef.target.set(body.getWorldPoint(localPoint));
        Vector2Pool.recycle(localPoint);

        return (MouseJoint) this.mPhysicsWorld.createJoint(mouseJointDef);
    }

    private void addFace(final float pX, final float pY) {
        this.mFaceCount++;
        Debug.d("Faces: " + this.mFaceCount);

        final AnimatedSprite face;
        final Body body;

        if(this.mFaceCount % 2 == 0) {
            face = new AnimatedSprite(pX, pY, this.mBoxFaceTextureRegion, this.getVertexBufferObjectManager());
            body = PhysicsFactory.createBoxBody(this.mPhysicsWorld, face, BodyType.DynamicBody, FIXTURE_DEF);
        } else {
            face = new AnimatedSprite(pX, pY, this.mCircleFaceTextureRegion, this.getVertexBufferObjectManager());
            body = PhysicsFactory.createCircleBody(this.mPhysicsWorld, face, BodyType.DynamicBody, FIXTURE_DEF);
        }
        face.setUserData(body);
        face.animate(200);

        this.mScene.registerTouchArea(face);
        this.mScene.attachChild(face);

        this.mPhysicsWorld.registerPhysicsConnector(new PhysicsConnector(face, body, true, true));
    }

    // ===========================================================
    // Inner and Anonymous Classes
    // ===========================================================
}

我试图改变引力，但似乎没有任何附加物。

    this.mPhysicsWorld = new PhysicsWorld(new Vector2(0, -10), false);

Answer 1

没有引力：

enter code here`this.mPhysicsWorld = new PhysicsWorld(new Vector2(0, 0), false);

这是反重力或〜1G以上：

this.mPhysicsWorld = new PhysicsWorld(new Vector2(0, -10), false);

这是右边的~1G：

this.mPhysicsWorld = new PhysicsWorld(new Vector2(10, 0), false);

没有重力的andengine mousejoint

1 个答案: