c# - 如何在 Unity (ECS) 中旋转四元数并计算方向向量

Question

我开始使用 ECS，我有一个旋转组件(四元数)和一个平移组件(float3)。我正在编写一个系统来处理用户输入并旋转和/或向前移动播放器。

问题是我不知道该怎么做。我认为现有的 API 是缺乏的。

// Before it was easy
if (Input.GetKey(KeyCode.W))
    var newPostion = new Vector3(player.Position.x, player.Position.y, 0.3f)
                    + _playerTransform.up * Time.deltaTime * PlayerSpeed;

if (Input.GetKey(KeyCode.A))
    _playerTransform.Rotate(new Vector3(0, 0, PlayerRotationFactor));

// now it is not - that's part of the system's code
Entities.With(query).ForEach((Entity entity, ref Translation translation, ref Rotation rotation) =>
{
    float3 tmpTranslation = translation.Value;
    quaternion tmpRotation = rotation.Value;

    if (Input.GetKey(KeyCode.W))
        // how to retrieve forward vector from the quaternion
        tmpTranslation.y += Time.deltaTime * PlayerSpeed; 

    if (Input.GetKey(KeyCode.A) || Input.GetKey(KeyCode.LeftArrow))
        // this always set the same angle
        tmpRotation = quaternion.RotateZ(PlayerRotationFactor); 

    // ECS need this
    var newTranslation = new Translation { Value = tmpTranslation };
    PostUpdateCommands.SetComponent(entity, newTranslation);
    var newRotation = new Rotation { Value = tmpRotation };
    PostUpdateCommands.SetComponent(entity, newRotation);
});

Answer 1

要从四元数中获取向量，您可以简单地将它与前向向量相乘，例如:

if (Input.GetKey(KeyCode.W))
{
    Vector forward = tmpRotation * float3(0,0,1);
    tmpTranslation += forward * Time.deltaTime * PlayerSpeed;
}

对于旋转部分，如您所说，//始终设置相同的角度。看起来你正在创造一个新的静态角度。尝试改变以与当前角度相乘，就像四元数相乘以组合一样。示例:

if (Input.GetKey(KeyCode.A) || Input.GetKey(KeyCode.LeftArrow))
{
    tmpRotation = mul(tmpRotation, quaternion.RotateZ(PlayerRotationFactor));
}

旁注:我对 Unity ECS 也有点陌生，我没有测试过上面的代码。