实现一个基本的粒子系统，该基本粒子系统必须具有以下模块：粒子生成、给粒子施加力（例如：重力、拖力等）、粒子的碰撞效果（例如与其他几何体碰撞，并反弹回来）。-Achieve a basic particle system, the elementary particle system must have the following modules: particle generation, to the particles to exert force (eg: gravity, drag force, etc.), particle collision effects (such as collision with other geometry, and bounce back).