Floor and Sphere collision, strange physic behavior

Hi everyone !

I am having a strange behavior with what I believed was a simple game... I searched on the web for questions and answers but couldn't find anything useful so far.

Let me explain my problem :

I have a Sphere (the simple one, made in Unity) that is my character. It has a rigidbody as well as a sphere collider. The rigidbody uses gravity and is also modified with a script of mine to make the ball go left or right like this :

 void Update()
 {
     movement = Input.GetAxis("Horizontal");
 }
 
 void FixedUpdate()
 {
     Vector3 velocity = rigidbody.velocity;
         
     velocity.x = movement * speed;
     velocity.z = Mathf.Clamp(velocity.z, 0, maximumSpeed);
         
     rigidbody.velocity = velocity;
 }

Basically, the script handles the X movement as well as a Z limited speed. The Z is handled with a Constant Force component pushing the sphere on Z. (and only on Z)

With that, I have a floor that is a simple cube, scaled, just below my sphere so it can roll over it. The floor is managed with another script that handles the generation of an infinite floor (more of a corridor really).

 public void Update()
 {
     float currentPosition = player.transform.position.z;
 
     if (currentPosition + playerOffsetBeforeNextSpawn >= currentOffset + offsetBeforeNextSegment)
         {
             currentOffset += offsetBeforeNextSegment;
 
             GameObject segment = PickSegment();
             segment.transform.position = new Vector3(0, 0, currentOffset);
         }
 
         RecycleOldSegments();
 }

The segments are nicely side by side (no space between them). The script uses a pool of segments (the one behind the camera are recycled). So the segments are just moving in Z to continue the corridor.

What goes wrong is this : From time to time, my sphere (capped at 100 z velocity) will jump off, with a random amplitude. There is no script that affects its Y velocity and I know the cause, I just can't get it working correctly !

I think the problem is due to the segments being segments and not a unique mesh. The sphere would collide with the "new" ground and go crazy over it !

I can't see a solution for making it not jumping so randomly... :(

• have the following constraints :*

  • My sphere need to be able to jump so I can't used the rigidbody constraints.

  • I need to create the corridor segment by segment and can't simply use a unique mesh.

With all that said, I am posting here to know if anyone of you already faced this problem? Is there a better way to achieve what I am trying to do? How? Maybe the constant force is not appropriate here, how can I achieve an automatic acceleration without it and no input ?

Thank you for your time and many thanks in advance ! =D

PS : This behavior happens even without doing anything (movement = 0) and the sphere rolling straight ahead!