Help adjusting my steering class; Rotation jitter

Hello,

I have ships sailing around a sphere and each ship has a standard forward motion. So I give each ship it's own steering class and FSM (state machine) to handle avoidance or steering towards targets and what not. However if a ship sees an enemy, it will steer away, but when it resolves the collisions it will steer to the wall again to avoid the enemy causing a jitter like behavior.

How do I fix this?

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Steering
5. {
6.     private BaseShip ship;
7.     private Vector3 forwardFeeler;
8.     private Vector3 rightFeeler;
9.     private Vector3 leftFeeler;
10.    
11.    
12.     private float minimumCollisionDistance = 1; // -- when distance to the hit.point is 1, speed is 0
13.     private float distanceThreshold = 4; // -- The distance after which the slow down occurs
14.    
15.    
16.     private float increasedRotateSpeed = 7;
17.    
18.     public Steering( BaseShip owner)
19.     {
20.         ship = owner;
21.     }
22.     private bool SteerAwayFromCollision()
23.     {
24.         forwardFeeler = ship.transform.forward * ship.forwardFeelerLength;
25.         rightFeeler = ship.transform.TransformDirection( ship.smallFeelerAngle, 0 , ship.whiskerFeelerLength );
26.         leftFeeler = ship.transform.TransformDirection( -ship.smallFeelerAngle, 0 , ship.whiskerFeelerLength );
27.        
28.         RaycastHit forwardHit;
29.         RaycastHit rightHit;
30.         RaycastHit leftHit;
31.        
32.         Vector3 newPos = ship.transform.position+ship.transform.up * ship.scanHeightOffset;
33.        
34.         #if UNITY_EDITOR
35.         Debug.DrawRay(newPos, forwardFeeler , Color.red);
36.         Debug.DrawRay(newPos, rightFeeler , Color.red);
37.         Debug.DrawRay(newPos, leftFeeler , Color.red);
38.         #endif
39.        
40.         bool forwardRay = Physics.Raycast(newPos, forwardFeeler.normalized, out forwardHit, ship.forwardFeelerLength);
41.         bool rightRay   = Physics.Raycast(newPos, rightFeeler.normalized, out rightHit, ship.whiskerFeelerLength);
42.         bool leftRay    = Physics.Raycast(newPos, leftFeeler.normalized, out leftHit, ship.whiskerFeelerLength);
43.  
44.         if(!forwardRay  !rightRay  !leftRay)
45.             return false;
46.        
47.         else if(forwardRay)
48.         {
49.             CheckDistanceToCollisionPoint( forwardHit );
50.            
51.             if( rightRay )
52.                 ship.transform.Rotate(ship.transform.up, (-ship.RotateSpeed * increasedRotateSpeed) * Time.deltaTime, Space.Self);
53.             else if( leftRay )
54.                 ship.transform.Rotate(ship.transform.up, (ship.RotateSpeed * increasedRotateSpeed)  * Time.deltaTime, Space.Self);
55.             else
56.             {  
57.                 Vector3 relativePoint = ship.transform.InverseTransformDirection( forwardHit.normal );
58.                            
59.                 if(relativePoint.x < 0.0f)
60.                 {
61.                     ship.transform.Rotate(ship.transform.up, (-ship.RotateSpeed * increasedRotateSpeed) * Time.deltaTime, Space.Self);
62.                 }
63.                 else if (relativePoint.x > 0.0f)
64.                 {
65.                     ship.transform.Rotate(ship.transform.up, (ship.RotateSpeed * increasedRotateSpeed) * Time.deltaTime, Space.Self);
66.                 }
67.             }
68.         }
69.         else if( rightRay )
70.             ship.transform.Rotate(ship.transform.up, (-ship.RotateSpeed * increasedRotateSpeed) * Time.deltaTime, Space.Self);
71.         else if( leftRay )
72.             ship.transform.Rotate(ship.transform.up, (ship.RotateSpeed * increasedRotateSpeed) * Time.deltaTime, Space.Self);
73.            
74.         return true;
75.     }
76.     public void SteerTowardsTarget( Transform target )
77.     {
78.         if( SteerAwayFromCollision() )
79.             return;
80.        
81.         Vector3 relative  = ship.transform.InverseTransformPoint( target.position );
82.         float angle = (Mathf.Atan2(relative.x, relative.z) * Mathf.Rad2Deg) * Time.deltaTime ;
83.    
84.         ship.transform.Rotate (0, angle * Time.deltaTime * ship.RotateSpeed, 0);
85.     }
86.     public void SteerAwayFromTarget( Transform target )
87.     {
88.         //Steer away from any possible collisions
89.         if( SteerAwayFromCollision() )
90.             return;
91.        
92.         //Otherwise
93.         Vector3 direction = ship.transform.InverseTransformDirection( target.position );
94.         Vector3 relative = -direction;
95.         float angle = (Mathf.Atan2(relative.x, relative.z) * Mathf.Rad2Deg) * Time.deltaTime;
96.        
97.         ship.transform.Rotate (0, angle  * Time.deltaTime * ship.RotateSpeed, 0);
98.     }
99.  
100.     private void CheckDistanceToCollisionPoint( RaycastHit hit)
101.     {
102.         //Check distance to collision point
103.         float distance = Vector3.Distance(ship.transform.position, hit.point);
104.         if( distance < 2 )
105.         {
106.             //start slowing down the ship
107.             ship.ForwardSpeed = ship.m_speed * (distance / distanceThreshold);
108.             Debug.Log( ship.ForwardSpeed );
109.             if(distance < minimumCollisionDistance) ship.ForwardSpeed = 0;
110.         }
111.         //Otherwise, if the speed doesn't match the standard speed, bring it back up to speed
112.         /*else if( ship.ForwardSpeed != ship.m_speed )
113.         {
114.             ship.ForwardSpeed += 0.1f;
115.             if(ship.ForwardSpeed > ship.m_speed)
116.                 ship.ForwardSpeed = ship.m_speed;
117.         }*/
118.        
119.     }
120. }

 

Hi Raziel,

Not sure if you already fixed the issue but I have the same problem and these are the things that have helped me mitigate it:

- Use acceleration on the rotation, this will soften the motion a bit.
- Average the two rotations
- Establish a threshold to stop rotating in one direction and start the other one

I'd like to know how you solved it if you already did.

Regards!