Rigidbody.detectCollisions

Description

Should collision detection be enabled? (By default always enabled).

Disabling collision detections is useful when you have a ragdoll which is setup to be kinematic and you want to avoid heavy collision detection calculations on that rigidbody. detectCollisions is not serialized. This means it doesn't show up in the Inspector and when Instantiating the rigidbody or saving it in a Scene, it will not be saved.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
    public Rigidbody rb;

    void Start()
    {
        rb = GetComponent<Rigidbody>();
    }

    // Let the rigidbody take control and detect collisions.
    void EnableRagdoll()
    {
        rb.isKinematic = false;
        rb.detectCollisions = true;
    }

    // Let animation control the rigidbody and ignore collisions.
    void DisableRagdoll()
    {
        rb.isKinematic = true;
        rb.detectCollisions = false;
    }
}