Java libGDX - Problems with changing texture size randomly at runtime

Question

I'm programming my own version of "FlappyBird", but I stumbled upon some problems.

I have four different textures (towers), which should have a random height (with a specified range), but the problems I'm facing are:

• If I generate the random numbers outside my drawTowers() method, then then all towers have different heights, but the height does not change
• If I generate the random numbers inside my drawTowers() method, then a lot of towers with different height are shown while changing every millisecond

Here is my drawTowers() method:

Random r = new Random();
int low = 0;
int high = 25;
int result1 = r.nextInt(high-low) + low;
int result2 = r.nextInt(high-low) + low;
int result3 = r.nextInt(high-low) + low;
int result4 = r.nextInt(high-low) + low;

private void drawTowers() {

    batcher.draw(AssetLoader.texture1, tower1.getX(), tower1.getY() + tower1.getHeight() - result1, 
           tower1.getWidth(), midPointY - (tower1.getHeight())); 


    batcher.draw(AssetLoader.texture2, tower2.getX(), tower2.getY() + tower2.getHeight() - result2,
           tower2.getWidth(), midPointY - (tower2.getHeight()));

    batcher.draw(AssetLoader.texture3, tower3.getX(), tower3.getY() + tower3.getHeight() - result3,
         tower3.getWidth(), midPointY - (tower3.getHeight()));

    batcher.draw(AssetLoader.texture4, tower4.getX(), tower4.getY() + tower4.getHeight() - result4,
            tower4.getWidth(), midPointY - (tower4.getHeight()));

}

I also have the same problem for the gap between two towers. I want the gap to have a random range (with specified minimum and maximum). So I used two classes: A ScrollHandler and a Scrollable .

This is what my ScrollHandler class looks like:

public class ScrollHandler {

private Tower tower1, tower2, tower3, tower4;
public static final int SCROLL_SPEED = -59;

Random r = new Random();
int low = 90;
int high = 110;
int result = r.nextInt(high-low) + low;

public final int TOWER_GAP = result; 

public ScrollHandler(float yPos) {

    tower1 = new Tower(210, 0, 25, 0, SCROLL_SPEED);
    tower2 = new Tower(tower1.getTailX() + TOWER_GAP, 0, 25, 0, SCROLL_SPEED);
    tower3 = new Tower(tower2.getTailX() + TOWER_GAP, 0, 25, 0, SCROLL_SPEED);
    tower4 = new Tower(tower3.getTailX() + TOWER_GAP, 0, 25, 0, SCROLL_SPEED);
}

public void update(float delta) {
    // Update our objects

    tower1.update(delta);
    tower2.update(delta);
    tower3.update(delta);
    tower4.update(delta);

    // Check if any of the pipes are scrolled left,
    // and reset accordingly
    if (tower1.isScrolledLeft()) {
        tower1.reset(tower4.getTailX() + TOWER_GAP);
    } else if (tower2.isScrolledLeft()) {
        tower2.reset(tower1.getTailX() + TOWER_GAP);
    } else if (tower3.isScrolledLeft()) {
        tower3.reset(tower2.getTailX() + TOWER_GAP);
    } else if (tower4.isScrolledLeft()) {
        tower4.reset(tower3.getTailX() + TOWER_GAP);
    }
}
}

And here is my Scrollable class:

public class Scrollable {

protected Vector2 position;
protected Vector2 velocity;
protected int width;
protected int height;
protected boolean isScrolledLeft;

public Scrollable(float x, float y, int width, int height, float scrollSpeed) {
    position = new Vector2(x, y);
    velocity = new Vector2(scrollSpeed, 0);
    this.width = width;
    this.height = height;
    isScrolledLeft = false;
}

public void update(float delta) {
    position.add(velocity.cpy().scl(delta));

    // If the Scrollable object is no longer visible:
    if (position.x + width < 0) {
        isScrolledLeft = true;
    }
}

// Reset: Should Override in subclass for more specific behavior.
public void reset(float newX) {
    position.x = newX;
    isScrolledLeft = false;
}

public boolean isScrolledLeft() {
    return isScrolledLeft;
}

public float getTailX() {
    return position.x + width;
}

public float getX() {
    return position.x;
}

public float getY() {
    return position.y;
}

public int getWidth() {
    return width;
}

public int getHeight() {
    return height;
}

I don't know what exactly I have to change to get a random height and random gap every time it appears again. Maybe I have to work with the texture itself? Thanks in advance!

texture1 = new Texture("png/turm_gryffindor.png");
    gryffindor = new TextureRegion(texture1, 136, 16, 15, 1);

Answer 1

Recreate the random numbers in the tower reset method and at the start (when you initialise the game). That way when they are moved back to the start they will have a new random height.