统一跳跃技工不起作用

Question

I have a game in a 3D space, and rigidbody comp. to a player. I have implemented a jump mechanic that is not working at intended, with this code:

using UnityEngine;

public class PlayerMovement : MonoBehaviour
{

    public bool Travel;
    public Rigidbody rb;
    public Transform tf;
    public bool Grounded;
    public float speed;

    int OnRail = 2;

    void Update ()
    {
        float speed = 1f * Time.deltaTime;
        if (Input.GetKeyDown("d") && OnRail < 3)
        {
            tf.Translate(5.4f, 0f, 0f);
            OnRail++;
        }
        else if (Input.GetKeyDown("a") && OnRail > 1)
        {
            tf.Translate(-5.4f, 0f, 0f);
            OnRail--;
        }
    }

    void FixedUpdate ()
    {
        if (Travel)
        {
            rb.velocity = new Vector3(0, 0, speed * Time.deltaTime);
        }

        if (Input.GetKeyDown("space") && Grounded)
        {
            Grounded = false;
            rb.AddForce(new Vector3(0, 500000f * Time.deltaTime, 0));

        }

        if ((tf.position.y == 2f || tf.position.y == 10f) && rb.velocity.y == 0 && !Grounded)
        {
            Grounded = true;
        }
    }
}

The player is supposed to jump into the air, but only jumps almost no distance. The 2 and 10 Y positions are preset floors (I really don't need these 2 Y-coordinates. unless someone has a substitution for floor detection).

Answer 1

This is because GetKeyDown only occurs for one frame, meaning you are only applying a force upwards for that single frame. Additionally, Time.deltaTime is the amount of time it took to complete the last frame (a very small value), meaning you are applying a very small force upward. If you only want a single force applied on spacebar, there is no need to use Time.deltaTime here. Just do:

rb.AddForce(Vector3.up * 100f); // or some other reasonable multipliier

Answer 2

Hi for those that land on this looking for more information on their rigidbodies not behaving the way that they expected, I extracted bit of relevant information from Unity ForceMode's . Happy Developing.

    //Here, switching modes depend on button presses in the Game mode
    switch (m_ModeSwitching)
    {
        //This is the starting mode which resets the GameObject
        case ModeSwitching.Start:
            //This resets the GameObject and Rigidbody to their starting positions
            transform.position = m_StartPos;
            m_Rigidbody.transform.position = m_StartForce;
            //This resets the velocity of the Rigidbody
            m_Rigidbody.velocity = new Vector3(0f, 0f, 0f);
            break;

        //These are the modes ForceMode can force on a Rigidbody
        //This is Acceleration mode
        case ModeSwitching.Acceleration:
            //The function converts the text fields into floats and updates the Rigidbody’s force
            MakeCustomForce();
            //Use Acceleration as the force on the Rigidbody
            m_Rigidbody.AddForce(m_NewForce, ForceMode.Acceleration);
            break;

        //This is Force Mode, using a continuous force on the Rigidbody considering its mass
        case ModeSwitching.Force:
            //Converts the text fields into floats and updates the force applied to the Rigidbody
            MakeCustomForce();
            //Use Force as the force on GameObject’s Rigidbody
            m_Rigidbody.AddForce(m_NewForce, ForceMode.Force);
            break;

        //This is Impulse Mode, which involves using the Rigidbody’s mass to apply an instant impulse force.
        case ModeSwitching.Impulse:
            //The function converts the text fields into floats and updates the force applied to the Rigidbody
            MakeCustomForce();
            //Use Impulse as the force on GameObject
            m_Rigidbody.AddForce(m_NewForce, ForceMode.Impulse);
            break;


        //This is VelocityChange which involves ignoring the mass of the GameObject and impacting it with a sudden speed change in a direction
        case ModeSwitching.VelocityChange:
            //Converts the text fields into floats and updates the force applied to the Rigidbody
            MakeCustomForce();
            //Make a Velocity change on the Rigidbody
            m_Rigidbody.AddForce(m_NewForce, ForceMode.VelocityChange);
            break;
    }