如何在输入上增加/减少速度？

Question

I want to increment and decrement the speed on object movement with input. What would the best way to go about this?

Answer 1

Since there is no code i ll try my best to explain, whenever you are pressing down a key you can increase a variable and whenever you press another key you can decrease the variable. This should be done in the Update() method and it can go something like this

void Update()
{
    if (Input.GetKeyDown("a"))
    {
        variable++;
    }
    else if (Input.GetKeyDown("b"))
    {
        variable--;
    }
}

Answer 2

The best way to go really depends on the features that you want to implement in your game and how you want the object movement to feel.

This is one way to do exactly what you asked though

using UnityEngine;

[RequireComponent(typeof(Rigidbody2D))]
public class PlayerMovement : MonoBehaviour {

    private Rigidbody2D rigidbody2D;
    private Vector2 velocity;
    public float playerMoveSpeed = 6; //the value that you want

    private float HorizontalMov;
    private float VerticalMov;

    void Awake() {
        rigidbody2D = this.GetComponent<Rigidbody2D>();
    }

    void Update()
    {
        HorizontalMov = Input.GetAxis("Horizontal") * playerMoveSpeed * Time.deltaTime;
        VerticalMov = Input.GetAxis("Vertical") * playerMoveSpeed * Time.deltaTime;
        AddVelocity(new Vector2(HorizontalMov, VerticalMov));
        rigidbody2D.velocity = velocity;
    }

    public void AddVelocity(Vector2 newVelocity) {
        velocity += newVelocity;
    }

}

You can learn more about Input.GetAxis and RigidBody2D.velocity in the unity documentation