说明：  The concept of particle effects is very simple. Particle effects can be used to simulate fire, fireworks, water fountains, snow, rain, explosions and many other things. The effects are created by creating a definite number of particles. Depending on the need for performance and realistic appearance, the number of particles can range from 50 to thousands. Each particle has its own location, size, velocity, color, life and image. The particle engine controls the particles and makes them react according to the rules of the particle .