Particles/1.18

Particles are one of the few effects within the game that are used as polish to better improve immersion. Their usefulness also requires great caution due to how they are created and referenced in the game.

Sided Issues

Particles are problematic due to their presence only on the physical client. They have no existence on a server whatsoever. This means that if specific data from a server is needed, it needs to be synced from the server to create the particle on the client.

Creating a Particle

A particle can be broken up into four distinct classes. On the server, a ParticleType<?> holds a ParticleOptions to sync the information. On the client, a ParticleProvider is used to generate a Particle from the synced ParticleOptions. To be more specific, a ParticleType<?> holds the registry reference of the particle itself. A ParticleOptions hooks into a ParticleType<?> to send information to the ParticleProvider. A ParticleProvider creates the specified particle in some place within the level. Then, the Particle goes and handles the rendering logic to make it appear in game.

ParticleTypes

While there are a lot of different particles in vanilla, in almost all cases vanilla uses SimpleParticleType, a basic implementation of ParticleType and ParticleOptions. This is used whenever server data is not necessary to spawn the particle. The only vanilla particles that do not use SimpleParticleType are redstone dust and block/item texture dependent particles. When requiring server data, a direct implementation of ParticleOptions is needed. A good way is to extend ParticleType<?> and implement ParticleOptions on the same class. In the case of a more generic solution, an implementation of ParticleOptions can be referenced while the standard ParticleType<?> class is used.

ParticleTypes must be registered.

ParticleOptions

Beside the standard reference to a ParticleType<?>, a ParticleOptions is made up of two main methods and two accessory methods for compatibility across Minecraft usage.

First there are the sync methods:

ParticleOptions#writeToNetwork(FriendlyByteBuf)

ParticleOptions$Deserializer#fromNetwork(ParticleType, FriendlyByteBuf)

These two are used to sync information across the network. All information from the server should be synced in this fashion.

The other two are for compatibility with other Minecraft systems:

ParticleOptions#writeToString

ParticleOptions$Deserializer#fromCommand(ParticleType, StringReader)

These two are used to read/write data to NBT as well as get information to spawn the particle in the level using a command.

Particles

Particles will be left as an exercise to the reader as it is mainly about deciding what the reader wants to render to the screen. One of the most common classes to subclass, however, is TextureSheetParticle. This abstract class renders a texture specified by the user as the particle to go according to the logic rendered.

ParticleProviders

Finally, a particle must be created using a ParticleProvider. This simply just decides where the particle should be placed in the level at some speed in most cases. Since a Particle is not beholden to any particular ParticleType<?>, it can be reused over and over again in different factories if necessary.

A ParticleProvider must be attached to a ParticleType using ParticleEngine#register. If a particle has a json defined sprite location, then the ParticleEngine$SpriteParticleRegistration variant must be used instead as otherwise an exception will be thrown. This should be called during ParticleFactoryRegisterEvent on the mod event bus.

Important

ParticleProvider is only present on the client, so the event needs to be isolated via DistExecutor or some other method.

Spawning Particles

Particles can be spawned from a level instance. Each side, however, has a specific way of calling them. The ClientLevel can call either addParticle or addAlwaysVisibleParticle. The ServerLevel must call sendParticles as it sends a packet to the client level to call one of the other two methods. Calling the two ClientLevel methods on the server will result in nothing happening.