> For the complete documentation index, see [llms.txt](https://morningheartgames.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://morningheartgames.gitbook.io/docs/getting-started/extend-particle-input.md).

# Extend particle input

Currently, there are two subclasses in the project that inherit from `SSF_ParticleSource`, namely `SSF_LoadParticlesFromParticleSystem` and `SSF_LoadParticlesFromFile`. `SSF_ParticleSource` represents the source of particle data required for rendering and is also the starting point for extension.

Considering that users may have their own source of particle data, such as a particle solution system running in parallel with the GPU, or imported pre-made particle data, here we will explain how to extend the input of particle data.

### Particle Data Struct

The structure of particle data in SSF is as follows:

```
public struct SSF_particle
{
    public Vector3 position;
    public Color color;
    public float radius;
}
```

> If you modify the particle’s data structure, you need to pay attention to replacing 32 in `particleBuffer = new ComputeBuffer (getParticleNum (), 32);` in **SSF\_ParticleSource.cs** with the number of bytes of particle data. At the same time, corresponding changes should be made in `DepthColorThickness.shader`.

### Explain `SSF_ParticleSource`

The input and update of extended data is to create a new class inheriting from `SSF_ParticleSource` and implement the corresponding virtual function.

The following two member variables exist in `SSF_ParticleSource`:

```
protected ComputeBuffer particleBuffer;// Buffer sent to GPU
protected SSF_particle[] particlesData;// Particle Data for above buffer
```

Where `particleBuffer` is used to provide data to generate related textures for rendering.

You can notice that the following member function modifiers in `SSF_ParticleSource` are *public virtual*:

* SetupParticleBufferData ()
* UpdateParticleBufferData ()

In `SetupParticleBufferData` , `ParticlesData` needs to be created and assigned, and updated in `UpdateParticleBufferData ()` , neither of these operations need to involve `particleBuffer`.

### You should also implement `UpdateBounds()` , the bounds is used for culling out of view particles, which saves a lot performance.

### Example

You can also refer to `SSF_LoadParticlesFromParticleSystem`, this is a bit complicated and tedious.