How can i move circles in libgdx/android?

Question

Hey im currently programming on a game where you have to avoid asteroids(displayed as circles).

Here is the code how i create asteroids:

renderer = new ShapeRenderer();

RandomXS128 rand = new RandomXS128();
for (int i = 0; i < 20; i++) {
 circlePositions.add(
  new Vector2(
   rand.nextInt(Gdx.graphics.getWidth()),
   rand.nextInt(Gdx.graphics.getHeight())
  )
 );
 circlePositions.add(
  new Vector2(
   rand.nextInt(Gdx.graphics.getWidth()),
   rand.nextInt(Gdx.graphics.getHeight())
  )
 );
}

renderer.begin(ShapeType.Filled);

for (int i = 0; i < circlePositions.size; i++) {
 Vector2 pos = circlePositions.get(i);

 renderer.setColor(Color.GRAY);
 renderer.circle(pos.x, pos.y, 50);
}

renderer.end();

How can i add random movement to the circles?

Answer 1

You can create speedx and speedy or random direction variables in circleposition class and give them random values. But you also should update x and y of circle.

For example when you creating circlePositions class also add direction parameter and create new method called update() in circlePosition class.

 circlePositions.add(
                new Vector2(
                        rand.nextInt(Gdx.graphics.getWidth()), 
                        rand.nextInt(Gdx.graphics.getHeight()))
                        direction );

Set direction to random between 0 to 360 when calling. You can use libgdx's MathUtils.random() method.

 circlePositions.add(
                    new Vector2(
                            rand.nextInt(Gdx.graphics.getWidth()), 
                            rand.nextInt(Gdx.graphics.getHeight()))
                            MathUtils.random(360f) );

Change constructor as well.

public circlePosition(Vector2 position, float direction )
{
...
this.direction=direction;// now you have random direction stored in circlePosition class

}

In update() method of circlePosition class

void update()
{
 x+=MathUtils.cosDeg(direction)*speed;//You can simply change speed by setting speeds value 
 y+=MathUtils.sinDeg(direction)*3.6f;//Or you can just use float
} 

Dont forget to call circlePositions.update();