Why can't I jump?

Question

When I try to run this code on unity,everything works expect the jumping.Anyone know why?

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerMovement : MonoBehaviour
{
    public CharacterController controller;

    public float speed = 12f;
    public float gravity = -9.81f;
    public float jumpHeight;

    public Transform groundCheck;
    public float groundDistance = 0.4f;
    public LayerMask groundMask;

    Vector3 velocity;
    bool isGrounded;

    // Update is called once per frame
    void Update()
    {

        isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, groundMask);

        if(isGrounded && velocity.y < 0)
        {
            velocity.y = -2f;
        }

        float x = Input.GetAxis("Horizontal");
        float z = Input.GetAxis("Vertical");

        Vector3 move = transform.right * x + transform.forward * z;

        controller.Move(move * speed * Time.deltaTime);

        if(Input.GetButtonDown("Jump") && isGrounded);
        {
            velocity.y = Mathf.Sqrt(jumpHeight * -2f * gravity);
        }

        velocity.y += gravity * Time.deltaTime;

        controller.Move(velocity *Time.deltaTime);
    }
}

Answer 1

For jumping in unity you can just add a Vector3 to the object you want to make jump, if it is in movement unity calculate automatic the trajectory of the object.

Answer 2

Your problem is with this line here

velocity.y += gravity * Time.deltaTime;

Don't try add gravity yourself, unity will be handing this for you if you have a character controller

Answer 3

As suggested in the comment, First make the isGrounded a little more stable.

Use the character's RigidBody and AddForce(Vector3 force, ForceMode mode = ForceMode.Force); to implement jumps, as a Jump is an impulsive force applied on the character in the up direction. Directly using Move is not the best way of implementing a jump force.

Documentation for RigidBody.AddForce

Answer 4

using System.Collections;
using System.Collections.Generic; // <--  Since these are not utilized and not necessary for this code, defined by being grey in their Colour.
                                  // Consider Removing them, To stop using unnecessary Data / Library calls in your code
using UnityEngine;

public class PlayerMovement : MonoBehaviour
{
    /* THINGS TO KNOW */
    // Private - only members of this class have access.
    // Public -can be accessed outside of the script.
    // Public Static - can be accessed in other scripts by using  ( nameOfTheScript.VariableFromThatScript ) which are called Pointers.
    // Protected - means it's only available in the class itself and any child-class.
    // [SerializeField] private - Means that the variable is no longer publicly accessible, but can still be accessed inside the Editor (Inspector) of Unity
    // Giving you the chance to drag / drop your character controller and modify values of other variables (while not overwriting your values outside of your other scripts)
    // Always define if your variable is Public / Private or Protected, by default they will be Public.


    [SerializeField] private CharacterController controller;
    [SerializeField] private float speed = 12f;
    [SerializeField] private float gravity = -9.81f;
    [SerializeField] private float jumpHeight;  // !! On Default this Element is going to be 0, if Not Defined Within the Inspector !!!
    [SerializeField] private Transform groundCheck;
    [SerializeField] private float groundRadius = 0.4f; // groundDistance -> groundRadius ( As it defines the size of the Sphere made from GroundCheck element)
    [SerializeField] private LayerMask groundMask;

    private Vector3 velocity;
    [SerializeField] private bool isGrounded;

    void Update() // Called once per frame.
    {
        // Defines if the character IsGrounded  ( True or False )
        // 1) Find object groundCheck (dragged in the inspector for the code)
        // .position Getting its position where GroundCheck is at the current moment
        //,2) Make a Sphere with a radius of ..
        // 3) Define what LayerMask is going to be checked.
        isGrounded = Physics.CheckSphere(groundCheck.position, groundRadius, groundMask);

        if (isGrounded && velocity.y < 0) // !! Issue fixed  "  if (isGrounded && velocity.y < 0); "  You cannot have " ; " - breaker before your method brackets.
        {
            velocity.y = -2f;
        }

        /* Move these function into their separate methods.*/
        /* Makes it easier to read as well as Debug,
         in order to find where the issue in your code is taking place*/

        Move();
        Jump();
        controller.Move(velocity * Time.deltaTime);
    }

    private void Move()
    {
        float x = Input.GetAxis("Horizontal");
        float z = Input.GetAxis("Vertical");

        Vector3 move = transform.right * x + transform.forward * z;
        controller.Move(move * speed * Time.deltaTime);
    }
    private void Jump()
    {
        // Y Axis
        if (Input.GetButtonDown("Jump") && isGrounded)
        {
            velocity.y = Mathf.Sqrt(jumpHeight * -2f * gravity);
        }
        velocity.y += gravity * Time.deltaTime; // Applies gravity with (times) *  Last updated frame to next update frame.
    }
}

1. Make sure that you add : LayerMask to your object as well from which you are trying to jump from and check if you can jump. Found on this Picture ->

LayerMask Applied to The Floor Or Ground Object

2. On Player GameObject, Make sure that you have defined all variable values, as well as other GameObjects : such as " groundCheck " found on this Picture ->

Player Game Object Information In Inspector

3. Last put not least make sure you have defined JumpHeight in your Inspector of the Player

• Though there are a lot of improvements still to make, this is what I would suggest, having provided you with commenting for Each Change or Explanation of a function.