using UnityEngine;
using UnityEngine.InputSystem;

public class PlayerMovement : MonoBehaviour
{
    [SerializeField] private float speed = 10f;
    private Rigidbody body;

    private void Start() => body = GetComponent<Rigidbody>();

    private void FixedUpdate()
    {
        Keyboard kb = Keyboard.current;

        Vector3 move = Vector3.zero;
        if (kb.wKey.isPressed) move += Vector3.forward;
        if (kb.sKey.isPressed) move += Vector3.back;
        if (kb.aKey.isPressed) move += Vector3.left;
        if (kb.dKey.isPressed) move += Vector3.right;

        body.AddRelativeForce(move.normalized * speed);
    }
}

using UnityEngine;
using UnityEngine.InputSystem;

public class PlayerRotation : MonoBehaviour
{
    [SerializeField] private Transform player;         // тело
    [SerializeField] private Transform head;           // точка обзора
    [SerializeField] private float rotationSpeed = 0.1f;

    private float horAngle = 0f;
    private float verAngle = 0f;

    private void Start() => Cursor.lockState = CursorLockMode.Locked;

    private void Update()
    {
        Vector2 delta = Mouse.current.delta.ReadValue();

        horAngle += delta.x * rotationSpeed;
        verAngle -= delta.y * rotationSpeed;
        verAngle = Mathf.Clamp(verAngle, -30f, 60f);   // чтобы не кувыркалось

        player.rotation = Quaternion.Euler(0f, horAngle, 0f);
        transform.rotation = Quaternion.Euler(verAngle, horAngle, 0f);
        transform.position = head.position - transform.forward * 4f;
    }
}

[SerializeField] private float jumpUp = 6f;    // сила прыжка вверх
[SerializeField] private float jumpHor = 2f;   // подкрут вперёд
private Vector3 move;                 // курс: считаем в FixedUpdate, нужен и прыжку

// ↓ остаётся в FixedUpdate
    body.AddRelativeForce(move.normalized * speed);
    body.AddRelativeForce(-move.normalized * body.linearVelocity.magnitude);

// ↓ а прыжок переезжает в Update
    if (Keyboard.current.spaceKey.wasPressedThisFrame)
        body.AddRelativeForce(Vector3.up * jumpUp + move.normalized * jumpHor,
                              ForceMode.Impulse);

private int touchGround = 0;

private void OnCollisionEnter(Collision other) => touchGround++;
private void OnCollisionExit(Collision other)  => touchGround--;

private void Update()
{
    if (touchGround <= 0) return;    // в воздухе не прыгаем

    if (Keyboard.current.spaceKey.wasPressedThisFrame)
        body.AddRelativeForce(Vector3.up * jumpUp, ForceMode.Impulse);
}