feat(Presence): add toggle to reset position on headset collision

A new parameter has been added to the Player Presence script to
determine if the CameraRig position should be reset to a good known
position if the user's headset collides with another game object.

It is now possible with the `resetPositionOnCollision` parameter to
determine whether this action of position reset happens or not.

Assets/SteamVR_Unity_Toolkit/Scripts/VRTK_PlayerPresence.cs

@@ -7,6 +7,7 @@ public class VRTK_PlayerPresence : MonoBehaviour
     {
         public float headsetYOffset = 0.2f;
         public bool ignoreGrabbedCollisions = true;
+        public bool resetPositionOnCollision = true;
 
         private Transform headset;
         private Rigidbody rb;
@@ -58,7 +59,7 @@ private void OnUngrabObject(object sender, ObjectInteractEventArgs e)
 
         private void OnHeadsetCollision(object sender, HeadsetCollisionEventArgs e)
         {
-            if (lastGoodPositionSet)
+            if (resetPositionOnCollision && lastGoodPositionSet)
             {
                 SteamVR_Fade.Start(Color.black, 0f);
                 this.transform.position = lastGoodPosition;

README.md

@@ -579,6 +579,13 @@ The following script parameters are available:
   box collider and rigid body on the play area. This is very useful
   if the user is required to grab and wield objects because if the
   collider was active they would bounce off the play area collider.
+  * **Reset Position On Collision:** If this is checked then if the
+  Headset Collision Fade script is present and a headset collision
+  occurs, the Camera Rig is moved back to the last good known
+  standing position. This deals with any collision issues if a user
+  stands up whilst moving through a crouched area as instead of them
+  being able to clip into objects they are transported back to a
+  position where they are able to stand.
 
 An example of the `VRTK_PlayerPresence` script can be viewed in
 the scene `SteamVR_Unity_Toolkit/Examples/017_CameraRig_TouchpadWalking`.