Bullet.cs

using System.Collections;
using System.Collections.Generic;
using PicaVoxel;
using UnityEngine;

public class Bullet : MonoBehaviour
{
    public float Speed;
    public Vector3 Direction;
    
    public float ExplodeRadius;
    public float ParticleVelocity;
    
    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        transform.position += Direction * (Speed * Time.deltaTime);
    }

    private void OnCollisionEnter(Collision other)
    {
        var vol = other.gameObject.GetComponent<Volume>();
        
        // Bullet hit something so kill it even if it is not a PicaVoxel volume
        Destroy(gameObject);
        
        if (vol == null) return; // add other target object checks here - is an enemy? etc

        var explodePos = other.GetContact(0).point;

        // We have the point at which the bullet hits the collision mesh, now lets step through in the direction of travel until we hit a voxel
        for (var d = 0f; d < 100f; d += vol.VoxelSize)
        {
            var checkPoint = explodePos + (Direction * d);

            var vox = vol.GetVoxelAtWorldPosition(checkPoint);
            if (vox.HasValue && vox.Value.State==VoxelState.Active)
            {
                var particleBatch = vol.Explode(checkPoint, ExplodeRadius, 0, Exploder.ExplodeValueFilterOperation.GreaterThanOrEqualTo);
                // volume explosion returns a batch of particles which we then pass to the VoxelParticleSystem
        
                VoxelParticleSystem.Instance.SpawnBatch(particleBatch, pos => ((pos + Random.insideUnitSphere) - pos)*
                                                                              (Random.Range(ParticleVelocity - 1f, ParticleVelocity + 1f)));

                break;
            }
        }
    }
}