weird float problem

Question

I was using this simple script

 public float speed = 1f;

 public Rigidbody rb; 
 
 // Update is called once per frame
 void Update()
 {
    float xMov = Input.GetAxisRaw("Horizontal");
    float zMov = Input.GetAxisRaw("Vertical");

    rb.velocity = new Vector3(xMov, rb.velocity.y, zMov) * speed;
 }

It works just fine, but when I want to increase the speed to more than 1, it gives me this error as soon as I move

alt text

can someone help me, been trying to fix this problem for about a week now.

Answer 1

Best Answer

Answer by Eno-Khaon · Dec 27, 2021 at 05:28 AM

Aside from the fact that you're updating your velocity out of sync with physics updates (setting Rigidbody.velocity during Update() rather than FixedUpdate()), the main problem here is that you're accelerating on the Y-axis on every Update() cycle.

If we cut out the rest, you're doing this:

 rb.velocity = new Vector3(0f, rb.velocity.y, 0f) * speed;

Now, let's say your "speed" is set to 5:

 current Y-axis speed per Update():
 frame# | Y speed
 -------+--------
 0      | 1
 1      | 5
 2      | 25
 3      | 125
 4      | 625
 5      | 3125

As you can see, within a single second (60 frames, in this case), your Y-axis speed would accelerate to ~8.6^e41 times what it started at with a "speed" value of 5.

If we ignore the fact that directly setting velocity like this isn't the ideal approach to movement, the simple fix for this would be to only multiply the relevant values by your speed:

 rb.velocity = new Vector3(xMov * speed, rb.velocity.y, zMov * speed);

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elilittrell · Dec 27, 2021 at 06:40 PM 0

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Thanks man, beginner issue I guess,

weird float problem

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