private List<ParticleFactory> defaultParticleFactories() {
// Random seed
long seed = (long) Math.random();
// If asList() is used the resulting list will have a fixed size!
List<ParticleFactory> particleFactories = Arrays.asList(
new ParticleFactory(numOfParticles / 2, 1, 1, particleRadius,
PositionDistribution.RANDOM, VelocityDistribution.RANDOM,
particleMaxSpeed / 10, particleMaxSpeed / 10, particleMaxSpeed,
false, seed, seed),
new ParticleFactory(numOfParticles / 2, 1, -1, particleRadius,
PositionDistribution.RANDOM, VelocityDistribution.RANDOM,
particleMaxSpeed / 10, particleMaxSpeed / 10, particleMaxSpeed,
false, seed, seed));
return particleFactories;