刚体在 Unity 中不断移动 (AddForce)

Question

I want to make my rigidbody sphere move with the "WASD" keys, and so far it works except for a little problem. When I move the rigidbody, it keeps moving infinitely.

This is my code:

rig.AddForce(cam.transform.forward * movementForce * Time.deltaTime, ForceMode.VelocityChange);

Full code: https://pastebin.com/ntjAfDVv

Answer 1

Well if you don't press any key then you don't stop... You keep moving with whatever the current velocity is.

Also note that for the s key you multiply by movementForce * Time.deltaTime * tempAirMultiplier twice which will most probably result in a significantly lower force then expected!

I would probably do something like eg

    // Tracks if any of the WASD keys is pressed
    var gotInput = false;

    if (Input.GetKey(KeyCode.W))
    {
        rig.AddForce(cam.transform.forward * movementForce * Time.deltaTime * tempAirMultiplier, ForceMode.VelocityChange);
        gotInput = true;
    }
    if (Input.GetKey(KeyCode.A))
    {
        rig.AddForce(cam.transform.right * -movementForce * Time.deltaTime * tempAirMultiplier, ForceMode.VelocityChange);
        gotInput = true;
    }
    if (Input.GetKey(KeyCode.S))
    {
        var force = cam.transform.forward * -movementForce * Time.deltaTime * tempAirMultiplier; // Get relative movement
        // you can simply erase one component like this, no need to create a new Vector3 instance
        force.y = 0; 
        // Note that force already contains your multipliers "Time.deltaTime * movementForce * tempAirMultiplier"
        rig.AddForce(force, ForceMode.VelocityChange);
        gotInput = true;
    }
    if (Input.GetKey(KeyCode.D))
    {
        rig.AddForce(cam.transform.right * tempAirMultiplier, ForceMode.VelocityChange);
        gotInput = true;
    }

    // If none of the keys is pressed stop the rigidbody
    if(!gotInput)
    {
        rig.veolcity = Vector3.zero;
    }

Answer 2

GetKey returns true while the user holds down the key identified by the key KeyCode enum parameter. Check docs . So you might be adding lots of forces.

Maybe you need to try Input.GetKeyDown that returns true during the frame the user starts pressing down the key identified by name.

Answer 3

I actually could solve the problem by doing this. My answer:

rigid.drag = 1;

Inisde the FixedUpdate() function