Unity 2D 中的口吃运动

Question

So basically I am trying to make player movement system like one in RPG Maker with 8 directions. Somehow I succeded, but only partially. When I am trying to suddenly change direction for ex. from up to left, character stutter and do not want to move without releasing all keys first.

Gravity scale is disabled or more like set to 0, body type is dynamic.

Here is a code:

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

public class MoveChar : MonoBehaviour {

Rigidbody2D rigid;

public float Speed;

// Use this for initialization
void Start () {

    rigid = GetComponent<Rigidbody2D>();

}

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

//        float horiz = Input.GetAxis("Horizontal");

//        float vert = Input.GetAxis("Vertical");

    if(Input.GetKeyDown(KeyCode.W)) //________________________________________MOVING UP

    {
        rigid.velocity = new Vector2(rigid.velocity.x, 1 * Speed);
    }
    else if(Input.GetKeyUp(KeyCode.W))
    {
        rigid.velocity = new Vector2(0, 0);
    }

    if (Input.GetKeyDown(KeyCode.S)) //_______________________________________MOVING DOWN
    {
        rigid.velocity = new Vector2(rigid.velocity.x, -1 * Speed);
    }
    else if (Input.GetKeyUp(KeyCode.S))
    {
        rigid.velocity = new Vector2(0, 0);
    }


    if (Input.GetKeyDown(KeyCode.A)) //_______________________________________MOVING LEFT
    {
        rigid.velocity = new Vector2(-1 * Speed, rigid.velocity.y);
    }
    else if (Input.GetKeyUp(KeyCode.A))
    {
        rigid.velocity = new Vector2(0, 0);
    }

    if (Input.GetKeyDown(KeyCode.D)) //_______________________________________MOVING RIGHT
    {
        rigid.velocity = new Vector2(1 * Speed, rigid.velocity.y);
    }
    else if (Input.GetKeyUp(KeyCode.D))
    {
        rigid.velocity = new Vector2(0, 0);
    }
}

Answer 1

Use Input.GetAxis(axisName) to avoid conflicting cases in your input code. Also, use AddForce to play nicely with other rigidbodies.

Vector2 oldV = rigid.velocity;
float horiz = Input.GetAxis("Horizontal");
float vert = Input.GetAxis("Vertical");

Vector2 newV = new Vector2(horiz * Speed, vert * Speed);
rigid.AddForce(newV-oldV, ForceMode2D.Impulse);

Alternatively, keep track of your own axes when keys are lifted/pressed down

public float horiz;
public float vert;

void Start() {
    horiz = 0f;
    vert = 0f;
    if (Input.GetKey(KeyCode.A)) horiz -= 1f;
    if (Input.GetKey(KeyCode.D)) horiz += 1f;
    if (Input.GetKey(KeyCode.S)) vert -= 1f;
    if (Input.GetKey(KeyCode.W)) vert += 1f;
}

void Update () {
    Vector2 oldV = rigid.velocity;

    if(Input.GetKeyDown(KeyCode.W)) vert += 1f;
    else if(Input.GetKeyUp(KeyCode.W)) vert -= 1f;

    if (Input.GetKeyDown(KeyCode.S)) vert -= 1f;
    else if (Input.GetKeyUp(KeyCode.S)) vert += 1f;

    if (Input.GetKeyDown(KeyCode.A)) horiz -= 1f;
    else if (Input.GetKeyUp(KeyCode.A)) horiz += 1f;

    if (Input.GetKeyDown(KeyCode.D)) horiz += 1f;
    else if (Input.GetKeyUp(KeyCode.D)) horiz -= 1f;

    Vector2 newV = new Vector2(horiz * Speed, vert * Speed);
    rigid.AddForce(newV-oldV, ForceMode2D.Impulse);
}

Answer 2

There is only a small problem with releasing the button. Add the original force in the direction that is not affected by the key. The whole script should look like this:

void Update()
{
    if (Input.GetKeyDown(KeyCode.W)) //________________________________________MOVING UP
    {
        rigid.velocity = new Vector2(rigid.velocity.x, 1 * Speed);
    }
    else if (Input.GetKeyUp(KeyCode.W))
    {
        rigid.velocity = new Vector2(rigid.velocity.x, 0);
    }

    if (Input.GetKeyDown(KeyCode.S)) //_______________________________________MOVING DOWN
    {
        rigid.velocity = new Vector2(rigid.velocity.x, -1 * Speed);
    }
    else if (Input.GetKeyUp(KeyCode.S))
    {
        rigid.velocity = new Vector2(rigid.velocity.x, 0);
    }


    if (Input.GetKeyDown(KeyCode.A)) //_______________________________________MOVING LEFT
    {
        rigid.velocity = new Vector2(-1 * Speed, rigid.velocity.y);
    }
    else if (Input.GetKeyUp(KeyCode.A))
    {
        rigid.velocity = new Vector2(0, rigid.velocity.y);
    }

    if (Input.GetKeyDown(KeyCode.D)) //_______________________________________MOVING RIGHT
    {
        rigid.velocity = new Vector2(1 * Speed, rigid.velocity.y);
    }
    else if (Input.GetKeyUp(KeyCode.D))
    {
        rigid.velocity = new Vector2(0, rigid.velocity.y);
    }
}

I hope this helps you.