delta bool particle state

src/VFX.cs

@@ -57,12 +57,14 @@ static class VFX
 
 public class Particle
 {
+    public DeltaBool state;
     public Vec3 pos, vel;
     public Quat ori;
     public float scl;
 
     public Particle()
     {
+        this.state = new(false);
         this.pos = Vec3.Zero;
         this.vel = Vec3.Zero;
         this.ori = Quat.Identity;