如何以定义的速度连续旋转精灵？ 有关游戏编程的一般问题

Question

I have an image which is rendered:

public void render(float delta) {
    batch.begin();
    batch.draw(new Sprite(new Texture("img1.png"), 64, 64), x, y);
    batch.end()

where x and y are used to center the sprite in the middle of the screen depending upon the screen's resolution.

1. I know I can use rotate(float degrees) to rotate it, but how do I do so continuously? I think I need to use delta time in some way, for example, x += 50 * Gdx.graphics.getDeltaTime(); but this does not rotate it continuously. The image is displayed for one frame before jumping elsewhere for one frame (seems like it's translating frame by frame instead).

2. If I want the (one) sprite to have multiple collision detections (for example, each colored arc here reacts differently, can overlaying an invisible circle on top that moves along with the arc and using math on that circle solve this problem? Instead of having a separate sprite for each colored arc. Is there an easier way to do this?

3. For a game, is it okay to not use layouts/XML for designing levels (ie hard coding everything instead)? Will this make it more difficult to make apps compatible for multiple screen resolutions?

I'm new to this so I hope these questions make sense.

Answer 1

Rotate your sprite forever in this way

public class TestGame extends Game {

    SpriteBatch spriteBatch;
    Sprite ball;
    Texture ballTex;
    private int spriteRotationSpeed=1;

    @Override
    public void create() {

        spriteBatch=new SpriteBatch();
        ballTex=new Texture("image/bone.png");
        ball=new Sprite(ballTex);
        ball.setSize(50,50);
        ball.setOrigin(25,25);
        ball.setPosition(0,0);


    }

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

        Gdx.gl.glClearColor(1,1,1,1);
        gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        spriteBatch.begin();
        ball.draw(spriteBatch);
        spriteBatch.end();
        rotateSprite();
    }

    private void rotateSprite(){

        float rotation=ball.getRotation();
        rotation+=spriteRotationSpeed;
        if(rotation>360)
            rotation-=360;
        ball.setRotation(rotation);
    }

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

    @Override
    public void dispose() {
        super.dispose();
        ballTex.dispose();
        spriteBatch.dispose();
    }
}