Extend Particle Inputs

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.

In SSF Particle2Fluid ShaderUtil (SSF) ,the input of particles is implemented by the base class SSF_ParticleSource .

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;
}

Note

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 and NoiseShader.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 SSF_TextureGenerator 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.

Example

The simplest example is SSF_LoadParticlesFromFile.cs.

public class SSF_LoadParticlesFromFile : SSF_ParticleSource
   {
       public UnityEngine.Object particleFile;
       public float particleRadius;
       public Color particleColor;
       [Range(0,2)]
       public int positionOrder_0=0;
       [Range(0,2)]
       public int positionOrder_1=2;
       [Range(0,2)]
       public int positionOrder_2=1;

       public override void setupParticleBufferData()
       {
           base.setupParticleBufferData();
           if (particleFile != null)
           {
               TextAsset asset = particleFile as TextAsset;
               string[] striparr = asset.text.Split(new string[] { "\r\n", " " }, StringSplitOptions.RemoveEmptyEntries);
               particle_num = striparr.Length / 3;
               print("Loaded particles : " + particle_num);
               particlesData = new SSF_particle[particle_num];
               for (int i = 0; i < particle_num; i++)
               {
                   particlesData[i].position = new Vector3(Convert.ToSingle(striparr[3 * i+positionOrder_0]),
                   Convert.ToSingle(striparr[3 * i + positionOrder_1]), Convert.ToSingle(striparr[3 * i + positionOrder_2]));
                   particlesData[i].radius = particleRadius;
                   particlesData[i].color = particleColor;
               }
           }
       }
       public override void updateParticleBufferData()
       {
           base.updateParticleBufferData();
       }

   }

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