c# - 播放器移动的具体而简单的代码无法按预期工作(XNA)

Question

问题:有时，当我的战斗机朝一个方向奔跑时(因为我按住方向按钮，如 A、D、左或右)，我迅速松开该方向的按钮并按下按钮对于相反的方向，战斗机继续朝第一个提到的方向奔跑。这不会一直发生，它是“随机的”。此外，这与跳跃/坠落无关，因为战斗机是否在空中并不重要。
我有 4 个类，其中战斗机运动在更新方法中受到监管:

输入类，只是一些函数

public static void UpdateNew(GameTime gt)
{
    // fires before any other update is called (before player/level/fighter update...)
    frameTime = (float)gt.ElapsedGameTime.TotalSeconds;
    ksNew = Keyboard.GetState();
    msNew = Mouse.GetState();
}
public static void UpdateOld()
{
     // fires after every other update is called (after player/level/fighter update...)
    ksOld = ksNew;
    msOld = msNew;
    scrollValue = msOld.ScrollWheelValue;
}
public static bool Down(Keys k)
{ return ksNew.IsKeyDown(k); }

播放器类:

Fighter fighter; //set in constructor, it's not null
public void Update()
{
    fighter.RunDirection = Input.Down(rightK).ToInt() - Input.Down(leftK).ToInt();
    fighter.Jump = Input.Down(jumpK);
    fighter.Punch = Input.Clicked(punchK);
}
// where .ToInt() converts bool to 1 if it's true, and to 0 if it's not true

战斗机类

public int              RunDirection
{ set { runMultiplier = MathHelper.Clamp(value, -1, 1); } }

public override void    Update              (float elTime, List<Entity> entities)
{
    // region: checks for jump, works fine

    AddForce(
         // X - Horizontal Force
         ((Math.Abs(Force.X) < runSpeed) ? runMultiplier * runSpeed * 5 * elTime : 0) // movement controls
         + ((runMultiplier == 0) ? -Force.X.Sign() * runSpeed * 5 * elTime : 0) // traction when not moving
         ,
         // Y - Vertical Force
         ((!canJump) ? 900 * elTime : 0) // gravity
         - jumpDecreasingSpeed * elTime // jump
         );

    // region: Check collision and puts force.X or force.Y to 0 when it's colliding with other 
    // entities and put's player next to that entity

    //set bool that stores last direction of looking (left/right)
    if (runMultiplier != 0) lookingRight = runMultiplier > 0;

    //checks if animation should be changed (idle, running, jumping or falling)
    CheckAnimation();

    //update currently playing animation
    currentAnim.Update(elTime);

    //stop fighters horisontal movement if it's small enough
    if (Math.Abs(Force.X) < 1) AddForce(-Force.X, 0);

    // after all calculations, move fighter by the force that is currently imacting him.
    Position += Force * elTime;
}

级别类

public void         Update          (float elTime)
{
    // PLAYERS
    p1.Update(); // updates only controls, as mentioned above, not the fighter itself.
    p2.Update();

    // update ENTITIES, player's fighters, and walls (their update method is empty)
    // player's fighters are added to maps "entities" list.
    for (int i = 0; i < map.entities.Count; i++)
        map.entities[i].Update(elTime, map.entities.Where(q => q != map.entities[i]).ToList());
}

每一帧的简要更新顺序
游戏主要更新
---输入.UpdateNew
---关卡更新
------播放器更新
------斗士.更新
----------检查玩家是否想让你移动，并增加力量(速度)
----------检查碰撞，如果碰撞则设置力为0移动
--------所有计算完成后，对当前位置加力
---输入.UpdateOld

问题:为什么会这样？为什么它如此“随机”？我知道这是有原因的，但我无法确定。

Answer 1

导致它的一种可能情况是当 Math.Abs​​(Force.X) >= runSpeed 然后你添加 0 力。

如果 Force.X >= runSpeed 那么 0

runMultiplier == 0 (false 由于立即切换) 然后 0

加力(0+0)

     // X - Horizontal Force
     ((Math.Abs(Force.X) < runSpeed) ? runMultiplier * runSpeed * 5 * elTime : 0) // movement controls
     + ((runMultiplier == 0) ? -Force.X.Sign() * runSpeed * 5 * elTime : 0) // traction when not moving

那么这将永远不会被执行，因为 Math.Abs​​(Force.X) >= 1(我假设 runspeed >= 1)。

//stop fighters horisontal movement if it's small enough
if (Math.Abs(Force.X) < 1) AddForce(-Force.X, 0);

这可能是为什么在一个方向立即被另一个方向替换的 1 帧缓冲区中切换键可以使您的力为 0 的一个可能原因；这将导致战斗机继续沿先前的方向前进。