Strange behavior of my jump script

Question

Hi, i'm new to unity and trying to write a simple player movement script on my own, with a jump set on space bar that has the basic rules of a video game jump (no jump mid-air, jump during a movement is taken in account...) Here is what i came up with : In FixedUpdate :

     if (Input.GetKeyDown("space") && transform.position.y < 0.5f )
         {
             Jump();
             
         } 


          void Jump(){
     rigidBody.AddForce (Vector3.up * jumpHeight);
 }

Jump is outside of FixedUpdate of course. My problem is that sometimes, the player object will only move by a few units and sometimes it'll make a huge jump. So far i couldn't find any pattern to understand the logic between the different jumps.

Is there a way to code a more reliable jump, i want to set a height and have my player object do a nice and smooth jump of that height. and if the player is moving during the jump, i want the object to jump in that direction.

Thanks for your help :)

Answer 1

Answer by abhishek7 · Jul 13, 2017 at 02:43 PM

Ok, so as for the grounding mechanism use OnCollisionEnter() and OnCollisionExit() to change a boolean for whether the object is grounded or not, and remove the transform.position.y<0.5 . To do this just place a tag on the ground object and change the boolean whenever it collides with the tagged ground.

Try using

 rigidBody.velocity = new Vector3(rigidBody.velocity.x, jumpHeight, rigidBody.velocity.z);

That should hopefully resolve your problem.

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Answer 2

Answer by springwater · Jul 13, 2017 at 02:44 PM

you should probably use forcemode.impulse or velocity change. https://docs.unity3d.com/ScriptReference/ForceMode.html

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WaifuSlayer · Jul 13, 2017 at 06:42 PM 0

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Thanks, but i already tried that and although it makes the jumps a bit more stable, i still have two distinct patterns that are randoms it seems...

Jwizard93 WaifuSlayer · Jul 13, 2017 at 06:57 PM 1

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The only explanation for the strange behavior (assuming there isn't other code interacting that you haven't posted) is due to the fact that you are getting input in a function that doesn't run every frame. It's hard to say when and how many times addforce will actually be called when you receive Input in FixedUpdate()

WaifuSlayer Jwizard93 · Jul 13, 2017 at 07:47 PM 0

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So, is there any way of fixing this? Apart from the jump function i only have planar movement which are designed pretty much like those in the survival shooter tutorial.

Answer 3

Answer by Mercbaker · Jul 13, 2017 at 08:08 PM

You can probably just avoid all these problems by adding a "Character Controller", Component on your Player object

Then just add the code from this official Unity script example onto your Player object.

You can edit the fine details on the Component, and the Player movement in the above script example.

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Strange behavior of my jump script

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