使用 AndEngine 和 Box2D 制作英雄跳跃

Question

I am new to and engine. currently i want to make my game hero jump using AndEngine and Box2D. I have tried a lot of ways to do so. But could not succeed.

Here is my code for making character walk left and right on touching left and right arrows displayed on screen. Now i want to make it jump on touching up arrow. Here is my code...

public jump(int pLayerCount, final BaseGameActivity game) {
    super(pLayerCount);
    this.game=game;

    gravity=new Vector2(0,SensorManager.GRAVITY_EARTH);
    physicsWorld=new PhysicsWorld(gravity, false);
    fixture=PhysicsFactory.createFixtureDef(1f, 1f, 1f);

    camera_height=game.getEngine().getCamera().getHeight();
    camera_width=game.getEngine().getCamera().getWidth();
    bottom=new Rectangle(0, camera_height-5,camera_width,3);

    PhysicsFactory.createBoxBody(physicsWorld, bottom,BodyType.StaticBody, fixture);
    this.registerUpdateHandler(physicsWorld);
    this.attachChild(bottom);

    //walking image
       texture=new Texture(256,256,TextureOptions.BILINEAR_PREMULTIPLYALPHA);
        tiletextureRegion=TextureRegionFactory.createTiledFromAsset(texture,game, "images/walk_forward.png",0,90,5,1);
        game.getEngine().getTextureManager().loadTexture(texture);
        walk_forward=new AnimatedSprite(0.0f,160.0f,tiletextureRegion);

        this.attachChild(walk_forward);


    //Up_arrow
    texture=new Texture(256,256,TextureOptions.BILINEAR_PREMULTIPLYALPHA);
    textureRegion=TextureRegionFactory.createFromAsset(texture,game, "images/up_arrow.png",0,0);
    game.getEngine().getTextureManager().loadTexture(texture);
    Sprite up_arrow=new Sprite(30.0f,10.0f,textureRegion){
    public boolean onAreaTouched(TouchEvent pSceneTouchEvent,
            float pTouchAreaLocalX, float pTouchAreaLocalY) 
    {   
            left_touch=false;
            right_touch=false;
            up_touch=true;
            return true;            
    }

};


    //Left Arrow
    texture=new Texture(256,256,TextureOptions.BILINEAR_PREMULTIPLYALPHA);
    textureRegion=TextureRegionFactory.createFromAsset(texture,game, "images/left_arrow.png",0,0);
    game.getEngine().getTextureManager().loadTexture(texture);
    Sprite left_arrow=new Sprite(2.0f,34.0f,textureRegion){
        public boolean onAreaTouched(TouchEvent pSceneTouchEvent,
                float pTouchAreaLocalX, float pTouchAreaLocalY) 
        {   
                left_touch=true;
                right_touch=false;
                walk_forward.animate(150);
                return true;            
        }

    };

    //right Arrow
    texture=new Texture(256,256,TextureOptions.BILINEAR_PREMULTIPLYALPHA);
    textureRegion=TextureRegionFactory.createFromAsset(texture,game, "images/right_arrow.png",0,0);
    game.getEngine().getTextureManager().loadTexture(texture);
    Sprite right_arrow=new Sprite(60.0f,34.0f,textureRegion){

        public boolean onAreaTouched(TouchEvent pSceneTouchEvent,
                float pTouchAreaLocalX, float pTouchAreaLocalY) 
        {   
                right_touch=true;
                left_touch=false;
                //walk_forward.animate(150);
                return true;            
            }
    };

    //Down Arrow
    texture=new Texture(256,256,TextureOptions.BILINEAR_PREMULTIPLYALPHA);
    textureRegion=TextureRegionFactory.createFromAsset(texture,game, "images/down_arrow.png",0,0);
    game.getEngine().getTextureManager().loadTexture(texture);
    Sprite down_arrow=new Sprite(30.0f,60.0f,textureRegion);

    this.attachChild(up_arrow);
    this.attachChild(left_arrow);
    this.attachChild(right_arrow);
    this.attachChild(down_arrow);
    this.registerTouchArea(right_arrow);
    this.registerTouchArea(left_arrow);
    this.registerTouchArea(up_arrow);
    this.setTouchAreaBindingEnabled(true);  


    //jumping image_physics
     texture=new Texture(256,256,TextureOptions.BILINEAR_PREMULTIPLYALPHA);
        textureRegion=TextureRegionFactory.createFromAsset(texture,game, "images/jump_up.png",0,90);
        game.getEngine().getTextureManager().loadTexture(texture);
        jump_up=new Sprite(0.0f,220.0f,textureRegion);
        this.attachChild(jump_up);  
        fixture_jump=PhysicsFactory.createFixtureDef(1f, 0f, 1f);
        jump_up_body=PhysicsFactory.createBoxBody(physicsWorld, jump_up,BodyType.DynamicBody, fixture_jump);
        //jump_up_body.fixedRotation=true;
        physicsWorld.registerPhysicsConnector(new PhysicsConnector(jump_up,jump_up_body));  
    //  physicsWorld.clearForces();
        hero_speed = 2; //just test and find values that work well
        hero_max_speed = 4;
        hero_normal = new Vector2(0, 0);
        jump_speed = 16;

}

protected void onManagedUpdate(float pSecondsElapsed)
{
    if(right_touch==true)
    {
        x=x+1f;
        walk_forward.setPosition(x, walk_forward.getY());
    }
    if(left_touch==true)
    {
        x=x-1f;
       walk_forward.setPosition(x, walk_forward.getY());
    }

    if(up_touch==true)
    {
        jump_up_body.applyLinearImpulse(new Vector2(0,  -jump_speed), jump_up_body.getWorldCenter());
        walk_forward.getY()+30);
    }
    super.onManagedUpdate(pSecondsElapsed);
}

Answer 1

Take a look at the AndEngine samples especially Physics Jump Example

Essentially to jump, you set the linear velocity of the Physics body.

Vector2 velocity = new Vector2(0, -50); //experiment with the numbers!!
body.setLinearVelocity(velocity);

Answer 2

player jump:

playerBody.setLinearVelocity(new Vector2(playerBody.getLinearVelocity().x+1,-10f));
playerBody.setLinearVelocity(new Vector2(2,playerBody.getLinearVelocity().y));

player move:

playerBody.setLinearVelocity((int)5, 400);              

Answer 3

First create your sprite and then add it to physics body.

Animatedsprite yas = new Animatedsprite(XPosition,YPosition, (ITiledTextureRegion) this.yourspriteregion, this.getVertexBufferObjectManager());

Body yasbody;
this.physicsworld.registerPhysicsConnector(new PhysicsConnector(yas, yasbody, true, true));

yasbody.setLinearVelocity(velocity);

Answer 4

You need set actual velocity x for to jump correctly. Example:

playerBody.setLinearVelocity(new Vector2(playerBody.getLinearVelocity().x,-jump_speed));