public void destroyPool(CogaenId poolId) {
		Pool pool = this.pools.remove(poolId);
		
		if (pool == null) {
			throw new RuntimeException("unkonwnn particle system pool  " + poolId);
		}
		
		for (ParticleSystem ps : pool.systems) {
			this.particleSystems.remove(ps);
		}
	}