Question the name 'velocity' does not exist in the current context

Hallo, I am trying to create a PraticleSystem from scratch, I only want to use scripts.
I managed to spawn particles from a fixed position with random velocities and apply gravity and an external drag force to them. The particles work great.

Now I am trying to change their velocity ( create a custom collision with an invisible cube of edge size = 5) but I face a problem with local/global variables. The particle and rb are defined in the SpawnParticle() class. I want to use their velocity and position properties in the Update() class to check for collision each second.

Here is my code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class PrefabSpawner : MonoBehaviour
6. {
7.     public GameObject prefabParticle;
8.  
9.     public Vector3 spawnPoint = Vector3.zero; // Set the spawn point at (0,0,0)
10.  
11.  
12.     public float maxVelocity = 10f; // Set the maximum velocity in the Inspector
13.  
14.     public Vector3 gravity = new Vector3(0, -9.81f, 0);
15.  
16.     public float spawnRate = 10f; //set the spawnrate, make it public for inspector testing
17.  
18.     private float timeSinceLastSpawn; //
19.  
20.     public float lifetime = 5f; //destroy particles after some time to avoid memory deplition
21.  
22.     public float forceDragCoef = 0.01f;
23.  
24.     public GameObject particle;
25.     public Rigidbody rb;
26.  
27.     private void Start()
28.     {
29.      
30.     }
31.     void Update()
32.     {
33.      
34.         timeSinceLastSpawn += Time.deltaTime;
35.  
36.         if (timeSinceLastSpawn >= 1f/spawnRate)
37.         {
38.             timeSinceLastSpawn = 0f;
39.             SpawnParticle();
40.  
41.            if (particle.transform.position.x >= 5 || particle.transform.position.x <= 5)
42.             {
43.                 rb.velocity.x = rb.veloctiy.x * (-1);
44.             }
45.            
46.         }
47.     }
48.  
49.  
50.     void SpawnParticle()
51.     {
52.         //create new particle
53.  
54.         var particle = GameObject.Instantiate(prefabParticle);
55.         var rb = particle.GetComponent<Rigidbody>();
56.  
57.         if (rb == null)
58.         {
59.             rb = particle.AddComponent<Rigidbody>(); // this fixes an error occured as the particle clones appeared empty
60.         }
61.  
62.         //spawn position
63.         particle.transform.position = spawnPoint;
64.  
65.         //spawn with random veloctiy
66.         particle.GetComponent<Rigidbody>().velocity = Random.insideUnitSphere * maxVelocity;
67.  
68.         //add gravity
69.  
70.         particle.GetComponent<Rigidbody>().AddForce(gravity, ForceMode.Acceleration);
71.  
72.  
73.         //destroy particle after some time
74.         Destroy(particle, lifetime);
75.         // add custom force of f(drag) = -k*velocity
76.         Vector3 forceDrag = -forceDragCoef * rb.velocity;
77.         rb.AddForce(forceDrag, ForceMode.Force);
78.  
79.  
80.         //add collision
81.         //BoxCollider collider = gameObject.AddComponent<BoxCollider>();
82.         particle.AddComponent<SphereCollider>();
83.         particle.GetComponent<SphereCollider>().enabled = true;
84.     }
85. }

I get the following error : the name 'velocity' does not exist in the current context

How can I make particle and rb objects available to be used in every class of the script ??

Thaanks !

 

**UPDATE**

I re-wrote the script an managed to create rb and particle as global objects but the if loop still is not working.

Code (CSharp):

1. public class ParticleSpawner2 : MonoBehaviour
2. {
3.     public GameObject particlePrefab;
4.     public List<Rigidbody> particleRigidbodies;
5.  
6.     public Vector3 gravity = new Vector3(0, -9.81f, 0);
7.     public Vector3 spawnPoint = Vector3.zero; // Set the spawn point at (0,0,0)
8.     public int lifetime = 5; //destroy particles after some time to avoid memory deplition
9.     public int maxParticles = 10;
10.     public int spawnRate = 50; //set the spawnrate, make it public for inspector testing
11.     public int maxVelocity = 50; // Set the maximum velocity in the Inspector
12.     private float timeSinceLastSpawn; //
13.     public float forceDragCoef = 0.01f;
14.  
15.     void Start()
16.     {
17.         // Spawn particles using the ParticleSpawner function
18.         ParticleSpawner();
19.     }
20.  
21.     void Update()
22.     {
23.  
24.         //spawn for each update
25.  
26.         timeSinceLastSpawn += Time.deltaTime;
27.  
28.         if (timeSinceLastSpawn >= 1f / spawnRate)
29.         {
30.             timeSinceLastSpawn = 0f;
31.             ParticleSpawner();
32.         }
33.         // Change the velocity of each particle
34.         foreach (Rigidbody rb in particleRigidbodies)
35.         {
36.             if (rb.position.x >= 2 || rb.position.x <= -2)
37.             {
38.                 rb.AddForce(new Vector3(-rb.velocity.x, rb.velocity.y, rb.velocity.z));
39.             }
40.             if (rb.position.y >= 2 || rb.position.y <= -2)
41.             {
42.                 rb.AddForce(new Vector3(rb.velocity.x, -rb.velocity.y, rb.velocity.z));
43.             }
44.             if (rb.position.z >= 2 || rb.position.z <= -2)
45.             {
46.                 rb.AddForce(new Vector3(rb.velocity.x, rb.velocity.y, -rb.velocity.z));
47.             }
48.             //if (rb.position.y >= 10 || rb.position.y <= -10)
49.             //{
50.             //  
51.             //}
52.             //if (rb.position.z >= 10 || rb.position.z <= -10)
53.             // {
54.             //    rb.AddForce(new Vector3(rb.velocity.x, rb.velocity.y, -rb.velocity.z));
55.             // }
56.         }
57.  
58.     }
59.  
60.     private void FixedUpdate()
61.     {
62.  
63.     }
64.  
65.     void ParticleSpawner()
66.     {
67.         // Spawn 10 particles
68.         for (int i = 0; i < maxParticles; i++)
69.         {
70.  
71.  
72.             GameObject particle = Instantiate(particlePrefab);
73.             Rigidbody rb = particle.GetComponent<Rigidbody>();
74.  
75.             if (rb == null)
76.             {
77.                 rb = particle.AddComponent<Rigidbody>(); // this fixes an error occured as the particle clones appeared empty
78.             }
79.  
80.             //spawn position at (0,0,0)
81.             particle.transform.position = spawnPoint;
82.  
83.             //spawn with random velocti
84.             Vector3 velocity = Random.insideUnitSphere * maxVelocity;
85.             rb.velocity = velocity;
86.  
87.             //add gravity
88.             particle.GetComponent<Rigidbody>().AddForce(gravity, ForceMode.Acceleration);
89.  
90.             // add custom force of f(drag) = -k*velocity
91.             Vector3 forceDrag = -forceDragCoef * rb.velocity;
92.             rb.AddForce(forceDrag, ForceMode.Force);
93.  
94.             //destroy particle after some time
95.             Destroy(particle, lifetime);
96.         }
97.     }
98. }

 

You seem to be reading from a list called particleRigidbodies, but never actually adding anything to it.
you should add the RigidBody to that list in line 79, once you know that rb != null.
Otherwise your particleRigidbodies-list will be empty, which means that the foreach in line 34 has nothing to loop over

 

Hallo SF_FrankvHoof,
Thank you for your answer, i added the rb to the list and it worked !
Thank you !