Rigidbody velocity close to 0 when moving

Hello,

I am quite new to Unity and am at a loss with the velocity of Rigidbodies.

In my scene, I have a terrain, cube with a box collider (default settings), a Rigidbody (default settings), and the following script.

Code (CSharp):

1.  
2. using UnityEngine;
3.  
4. public class test : MonoBehaviour
5. {
6.  
7.     void Update()
8.     {
9.         float horizontalMovement = Input.GetAxis("Horizontal");
10.         float verticalMovement = Input.GetAxis("Vertical");
11.  
12.         float movementMultiplyer = 2f;
13.  
14.         if (verticalMovement != 0)
15.         {
16.             transform.Translate(Vector3.forward * verticalMovement * Time.deltaTime * movementMultiplyer);
17.         }
18.  
19.         if (horizontalMovement != 0)
20.         {
21.             transform.Translate(Vector3.right * horizontalMovement * Time.deltaTime * movementMultiplyer);
22.         }
23.        
24.         Debug.Log(transform.GetComponent<Rigidbody>().velocity.z);
25.  
26.     }
27. }
28.  

When moving the cube I want to read its forward velocity.
Somehow the cube moves at around 2 units/s, but the Debug output prints values in the range of E-07 to E-05, so basically 0.
As the Unity Documentation stats:

Did I understand smth. wrong/where did I make a mistake/how to get the actual speed along an axis?

 

transform.Translate just "teleports" the object, so that's not perceived as velocity. You should either move the rigidbody using the Rigidbody.AddForce method, or mark it as Kinematic and use Rigidbody.MovePosition and Rigidbody.MoveRotation. In both cases you must call those methods from FixedUpdate, not from Update.

EDIT: Welcome to Unity!

 

Thank you!

The Documentation threw me off with

.

The AddForce function (all ForceModes) only worked, when the "Use Gravity" option was disabled on the cube. Do you know where that could come from?

For the script, I changed the Update to FixedUpdate, removed the Translate and added the AddForce

Code (CSharp):

1.     void FixedUpdate ()
2.     {
3.         float horizontalMovement = Input.GetAxis("Horizontal");
4.         float verticalMovement = Input.GetAxis("Vertical");
5.  
6.         float movementMultiplyer = 200f;
7.  
8.         if (verticalMovement != 0)
9.         {
10.             GetComponent<Rigidbody>().AddForce(Vector3.forward * verticalMovement * Time.deltaTime * movementMultiplyer, ForceMode.Acceleration);
11.         }
12.  
13.         if (horizontalMovement != 0)
14.         {
15.             GetComponent<Rigidbody>().AddForce(Vector3.right * horizontalMovement * Time.deltaTime * movementMultiplyer, ForceMode.Acceleration);
16.         }
17.        
18.         Debug.Log(transform.GetComponent<Rigidbody>().velocity.magnitude);
19.  
20.     }

 

This could come from the friction that your body was having with the collider it was standing on.
Also when dealing with forces I suggest at least PI controller (Proportional Integral)

 

You have to remove Time.deltaTime from the calculation too. The acceleration is a time-independent magnitude. It gets integrated along the timestep by the physics solver. Then adjust your magnitudes or multipliers accordingly.

And yes, the cube doesn't move because of the friction with the surface when gravity is enabled. You may want to learn about physics materials and frictions now

https://docs.unity3d.com/Manual/class-PhysicMaterial.html

 

Indeed the friction was the problem.

The cube is moving by now, but I still have some questions around this topic:
- Should only the cube, or the terrain, or both have PhysicMaterial?
- Is this (Collider, Rigidbody, PhysicMaterial) the "best" way to handle humanoid movement? The outcome of this way feels more vehicle-related.

Do you maybe have a good resource on hand about setting up a movement system? The ones I found usually use the provided CharacterController, transform.translate, or NavMeshAgents.