Water2D

Water simulation for libGDX games.

Allows to add a water type object to a Box2D world. This object, will interact with others dynamic bodies in the world in a similar way to water.

It's based on the following tutorials:

• Box2D C++ tutorials: Buoyancy - by iforce2d.net
• Make a Splash With Dynamic 2D Water Effects - by Michael Hoffman

Final result

Features

• Buoyancy
• Waves simulation
• Splash particles
• Interaction with others dynamic Box2D bodies
• Debug rendering

Configuration

It will be assumed that you already have a Box2D world and you just want to add a body that acts like water. If not, I recommend to you follow this tutorial: Box2D.

1. Add the following classes and assets to your project:

   • Water: the core class of the project.
   • WaterColumn: for waves simulation.
   • Particle: for splash particles
   • IntersectionUtils: utils for intersections, centroid, area, etc.
   • water.png
   • drop.png

2. Create a class that implements ContactListener interface and override the methods beginContact() and endContact() or modify the one you already have as below:

@Override
public void beginContact(Contact contact) {
   Fixture fixtureA = contact.getFixtureA();
   Fixture fixtureB = contact.getFixtureB();

   if(fixtureA.getBody().getUserData() instanceof Water && fixtureB.getBody().getType() == BodyType.DynamicBody){
     Water water = (Water) fixtureA.getBody().getUserData();
     water.getFixturePairs().add(new Pair<Fixture, Fixture>(fixtureA, fixtureB));
   }
   else if(fixtureB.getBody().getUserData() instanceof Water && fixtureA.getBody().getType() == BodyType.DynamicBody){
     Water water = (Water) fixtureB.getBody().getUserData();
     water.getFixturePairs().add(new Pair<Fixture, Fixture>(fixtureB, fixtureA));
   }
}

@Override
public void endContact(Contact contact) {
  Fixture fixtureA = contact.getFixtureA();
  Fixture fixtureB = contact.getFixtureB();

  if(fixtureA.getBody().getUserData() instanceof Water && fixtureB.getBody().getType() == BodyType.DynamicBody){
    Water water = (Water) fixtureA.getBody().getUserData();
     water.getFixturePairs().remove(new Pair<Fixture, Fixture>(fixtureA, fixtureB));
  }
  else if(fixtureB.getBody().getUserData() instanceof Water && fixtureA.getBody().getType() == BodyType.DynamicBody){
    Water water = (Water) fixtureB.getBody().getUserData();
     water.getFixturePairs().add(new Pair<Fixture, Fixture>(fixtureA, fixtureB));
  }
}

3. Set your ContactListener class to your Box2D world:

world.setContactListener(new MyContactListener());

4. Create a water object and its body position and size:

water = new Water();
water.createBody(world, x, y, width, height);

There is another water constructor Water(boolean waves, boolean splashParticles), in case you don't want to render waves or splash particles.

5. And last but not least, in the rendering part, you should update and draw the water object. This needs an orthographic camera:

water.update();
water.draw(camera);

You can see how everything is done in the classes GameMain and MyContactListener.

Compile and execute

From the project root folder:

gradlew desktop:dist
java -jar desktop\build\libs\desktop-1.0.jar