Multiple colliders problem!!

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1

I have a NPC with colliders on each head, body and 2 legs. When i instantiate a bullet it often hits 2 colliders. A leg and body or head and body. I have different animations for all the body parts. I am getting weired reacting because of multiple collisions. What can be done?
Any help would be appreciated.

2

You could place a guard that stops the subsequent collisions from being handled while the animation is playing.

void OnCollisionEnter(Collision c)
{
    if (animationIsPlaying)
        return;

    // Rest of your code.
}

However if you are looking for something more complex, perhaps you can draw ideas from this:

NPCBodypart.cs

using UnityEngine;

// Placed on each body part
public class NPCBodypart : MonoBehaviour
{
    public NPCScript npc;

    // Route all collisions from body part to main NPC script for processing.
    private void OnCollisionEnter(Collision collision)
    {
        npc.OnChildCollisionEnter(this, collision);
    }
}

NPCScript.cs

using UnityEngine;

// Placed on npc root
public class NPCScript : MonoBehaviour
{
    // Define for how long you want to ignore collisions from the same object after
    // a collision has registered.
    public float ignoreTimer = 0.2f;

    private ExpirySet<Collider> ignoredColliders = new ExpirySet<Collider>();

    private void Awake()
    {
        foreach (var child in GetComponentsInChildren<NPCBodypart>())
            child.npc = this;

        // Every so often, we prune the ExpirySet to reclaim memory.
        // It could be called more often for more precise Expiry, 
        // but it is probably not necessary.
        InvokeRepeating("Prune", ignoreTimer, ignoreTimer);
    }

    private void Prune()
    {
        ignoredColliders.Prune();
    }

    // Called from NPCBodypart.OnCollisionEnter
    public void OnChildCollisionEnter(NPCBodypart child, Collision collision)
    {
        if (ignoredColliders.Accept(collision.collider, GetExpireTime()))
        {
            // Process collision...
            // Multiple calls to OnChildCollisionEnter won't accept the same collider to enter 
            // this block until the expiry condition is met and the set has been pruned.
            // An idea would be to call back to child to respond to collision.
        }
    }

    private float GetExpireTime()
    {
        return Time.time + ignoreTimer;
    }
}

ExpirySet.cs

using System;
using UnityEngine;
using System.Collections.Generic;
using System.Linq;

public class ExpirySet<T>
{
    private readonly List<ExpiryPair> list = new List<ExpiryPair>();

    public bool Accept(T value, float time)
    {
        if (list.Any(ExpiryPair.WithKey(value)))
        {
            return false;
        }
        else
        {
            list.Add(new ExpiryPair(value, time));
            return true;
        }
    }

    public void Prune()
    {
        list.RemoveAll(ExpiryPair.HasExpired);
    }

    private class ExpiryPair
    {
        private readonly T key;
        private readonly float time;

        public ExpiryPair(T key, float time)
        {
            this.key = key;
            this.time = time;
        }

        public static bool HasExpired(ExpiryPair expiry)
        {
            return expiry.time < Time.time;
        }

        #region Predicate helpers, not thread safe
        // This approach was chosen to avoid generating memory at runtime. 
        // The downside is that it is not thread safe and subsequent calls to WithKey 
        // will cause results from previous calls to compare key with the most recent call.
        // It's a code design choice the author chose to take.
        private static T keyToCompare;
        private static Func<ExpiryPair, bool> keyCompare = 
            expiry => ReferenceEquals(expiry.key, keyToCompare);

        /// <summary>
        /// Predicate to test if ExpiryPair has key
        /// </summary>
        /// <param name="key">The key to text</param>
        /// <returns>Predicate that returns true if ExpiryPair has the specified key. 
        /// Warning: Do not cache result from this call, use result immediately.</returns>
        public static Func<ExpiryPair, bool> WithKey(T key)
        {
            keyToCompare = key;
            return keyCompare;
        }
        #endregion
    }
}