title: Sprite Kit different gravity for different sections
body: <p>I am building a flappy bird game where half of the level is above water, and the other half is below water.</p>
  
  <p>If your bird is in the air, there is regular gravity and when you tap, an impulse is applied going straight up.</p>
  
  <p>If your bird is in the water, gravity should be in the negative direction (going up) and be less. When you tap, an impulse is applied going straight down.</p>
  
  <p>Can I set a scene's gravity in different places?</p>
  
  <p>I thought of using a timer to apply negative forces if the bird is in the water, but it's all over the place.</p>
  
  <p>Also, I can't just change the entire scene's gravity because there are other SKSprite objects in the scene that should have different gravity applied to them (for instance one bird in the air should be flapping up when tapping, and a bird that dove into the water should be swimming down when tapping all at the same time).</p>