Rigidbody y velocity is stuck on 0, gravity is not turned off.

Question

Greetings, I've come across a pretty serious problem, the rigidbody player falls at an impossibly slow speed when close to the ground, the fault is of this code:

     Vector3 forwardVel = movementBase.transform.forward * speed * moveVertical;
     Vector3 horizontalVel = movementBase.transform.right * speed * moveHorizontal;
     
     if(Physics.Raycast(transform.position, -Vector3.up, out hit, distanceToGround + 0.1f))
     {
         if (hit.collider.rigidbody)
         {
             isGrounded = true;

             rigidbody.velocity = forwardVel + horizontalVel + hit.collider.rigidbody.velocity;
         }
         else
         {
             isGrounded = true;
             
             rigidbody.velocity = forwardVel + horizontalVel;
         }
     }
     else
     {
         isGrounded = false;

         var yVel = rigidbody.velocity;
         yVel.y = rigidbody.velocity.y;
         
         rigidbody.velocity = forwardVel / 20 + horizontalVel / 20 + yVel;
     }

Sadly, I can't find a way to fix this, the issue is that when the ray hits the ground, I set the velocity, this is necessary for the game to work, my solution of setting the yVel in midair doesn't work with the ground because if this happens, then any velocity settings are just accelerated far too much, I suspect this is because the yVel starts out from rigidbody.velocity, which results in just adding more and more velocity over time.

I've already tried using AddForce instead, same problem, except a little worse.

How can I fix this?, all the code here is in FixedUpdate.

Answer 1

Answer by Kamuiyshirou · Apr 30, 2014 at 09:12 PM

Hi dude! LIKE MY answer >

     using UnityEngine;
     using System.Collections;

     public class AddSpeedRigidBody : MonoBehaviour {

     public float speed = 10.0F;
     public float rotationSpeed = 100.0F;

     void Update() {
     float moveVertical = Input.GetAxis("Vertical") * speed;
     float moveHorizontal = Input.GetAxis("Horizontal") * rotationSpeed;
     moveVertical *= Time.deltaTime;
     moveHorizontal *= Time.deltaTime;
     transform.Translate(0, 0, moveVertical);
     transform.Rotate(0, moveHorizontal, 0);

     }
 }

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Kamuiyshirou · Apr 30, 2014 at 09:21 PM 0

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Solution is this CODE!

meat5000 ♦ · May 31, 2014 at 05:16 PM 0

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Dude, you don't Translate rigidbodies in that way. $$anonymous$$esses with Physics and Collision detection.

AddForce to rigidbodies.

I didn't -1 this, just so you know :D

Answer 2

Answer by tanoshimi · Apr 29, 2014 at 08:27 PM

Assuming you're calling this code every frame in FixedUpdate(), you're setting the rigidbody.velocity to be a sum of two Vector3s - forwardVel and horizontalVel - neither of which have a y component. Without a y component to a rigidbody's velocity, it won't fall.

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SVGK · Apr 29, 2014 at 08:32 PM 0

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Hmm, I see what you mean, but how should I add it?, adding Physics.gravity to the velocity makes it fall far too fast, with no speed buildup.

tanoshimi · Apr 29, 2014 at 10:25 PM 0

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The "correct" answer is that you shouldn't be setting rigidbody.velocity directly at all (as noted at http://docs.unity3d.com/Documentation/ScriptReference/Rigidbody-velocity.html) - ins$$anonymous$$d you should apply forces to the rigidbody.

SVGK · Apr 30, 2014 at 10:43 AM 0

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I would do that, but using forces makes controls incredibly slippery, which isn't good for a platformer game.

SVGK · Apr 30, 2014 at 08:23 PM 0

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Wait, would using physics materials with my force rigidbody allow me to stop things being slippery unless I want it to?, cause that would be sweet.

PouletFrit · May 30, 2014 at 03:22 PM 0

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Yes you could, physics materials have frictions and bounciness attributes

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Rigidbody y velocity is stuck on 0, gravity is not turned off.

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