Help Fluid Particles interaction Script

[josemendez]

Hi there,

If you run this script, it will result in a NullRefException error (visible in the console), and the script will halt execution.

This is because of this line:

Code:

emitter.speed = 0;

"emitter" will always be null because you only require a component of type ObiSolver to be present:

Code:

[RequireComponent(typeof(ObiSolver))]

But then you try to retrieve a ObiEmitter component, which is more than likely to be absent. So this call to GetComponent will return null:

Code:

emitter = GetComponent<ObiEmitter>();

Easiest fix is to just make the emitter member public, then assign the emitter instance trough the inspector:

Code:

using UnityEngine;
using Obi;

[RequireComponent(typeof(ObiSolver))]
public class KillFluidOnContact : MonoBehaviour
{
    ObiSolver solver;
    public ObiEmitter emitter;
    public float targetTime = 2.0f;

    void Awake()
    {
        solver = GetComponent<ObiSolver>();
    }

    private void Update()
    {
        targetTime -= Time.deltaTime;

        if (targetTime <= 0.0f)
        {
            timerEnded();
        }

    }

    void timerEnded()
    {
        if (emitter != null)
            emitter.speed = 0;
        else Debug.LogWarning("No se ha proporcionado un emisor a este script.");
    }


    void LateUpdate()
    {

        if (!isActiveAndEnabled)
            return;

        // iterate over all particles in the solver, looking for particles
        // that have had their diffusion data altered by contact with other particles.
        for (int i = 0; i < solver.particleToActor.Length; ++i)
        {
            // if this particle is part of an actor,
            if (solver.particleToActor[i] != null)
            {
                // if the "user" (aka diffusion) data is not either (1,0,0,0) or (0,0,0,0)
                if (solver.userData[i].x < 0.9f && solver.userData[i].x > 0.1f)
                {
                    // take a reference to the emitter that the particle belongs to, and kill it.
                    var emitter = solver.particleToActor[i].actor as ObiEmitter;
                    emitter.KillParticle(solver.particleToActor[i].indexInActor);
                }
            }
        }

    }
}

This is basics of the basics, tough. You should train your programming skills a bit further .