Question

I would like to use AndEngine’s particle system to create a splash(as in splashing water).

I have checked out the particle system example, but not really sure on what needs to be done to create a splash affect of water using the particle system.

Any idea’s?

Answer 1

I don’t know of any water splash simulation algorithms, so I’ll do what I think, but you will have to modify to make it look real.

Water splash animation in 2D will create many small water drops from a single location, then send each one in a different direction with an initial velocity, then each water drop slows down and fades out.

Try this out:

public ParticleSystem createParticleSystem(final TextureRegion waterDropTextureRegion) {
    //X & Y for the particles to spawn at.
    final float particlesXSpawn = 400;
    final float particlesYSpawn = 300;

    //Max & min rate are the maximum particles per second and the minimum particles per second.
    final float maxRate = 10;
    final float minRate = 5;

    //This variable determines the maximum particles in the particle system.
    final int maxParticles = 100;

    //Particle emitter which will set all of the particles at a ertain point when they are initialized.
    final PointParticleEmitter pointParticleEmtitter = new PointParticleEmitter(particlesXSpawn, particlesYSpawn);

    //Creating the particle system.
    final ParticleSystem particleSystem = new ParticleSystem(pointParticleEmtitter, maxRate, minRate, maxParticles, waterDropTextureRegion);

    //And now, lets create the initiallizers and modifiers.
    //Velocity initiallizer - will pick a random velocity from -20 to 20 on the x & y axes. Play around with this value.
    particleSystem.addParticleInitializer(new VelocityInitializer(-20, 20, -20, 20));

    //Acceleration initializer - gives all the particles the earth gravity (so they accelerate down).
    particleSystem.addParticleInitializer(new GravityInitializer());

    //And now, adding an alpha modifier, so particles slowly fade out. This makes a particle go from alpha = 1 to alpha = 0 in 3 seconds, starting exactly when the particle is spawned.
    particleSystem.addParticleModifier(new AlphaModifier(1, 0, 0, 3));

    //Lastly, expire modifier. Make particles die after 3 seconds - their alpha reached 0.
    particleSystem.addParticleModifier(new ExpireModifier(3));  

    return particleSystem;
}

I haven’t tested it, but I think it’d work. Try playing with the values to find an animation which looks reallistic.

The method receives an argument which is a ready texture region for each particle, in your case I guess that’d be a water drop.

After you call this method and get a ParticleSystem, just attach it to your scene:

final ParticleSystem particleSystem = createParticleSystem(...);
scene.attachChild(particleSystem);