Tiled Map Game Player touch controls

@Override
public boolean touchDown(int screenX, int screenY, int pointer, int button) {
    animationTime = 0;

    float width = Gdx.graphics.getWidth();
    velocity.x = speed * Math.signum(screenX - width / 2); // hard
    // velocity.x = speed * (screenX - width / 2) / width * 2; // fade

    float height = Gdx.graphics.getHeight();
    if(canJump && screenY < height / 2) { // experiment by changing the 2 to change how high the touch has to be to jump
        velocity.y = speed / 1.8f;
        canJump = false;
    }

    return true;
}

@Override
public boolean touchUp(int screenX, int screenY, int pointer, int button) {
    animationTime = 0;
    velocity.x = 0;
    return true;
}