c++ - 新旧位置之间的速度

Question

我在这里看到了通过为 UNITY 保存旧位置来提高速度的帖子，一些代码:

void TestVelocity(Vector3& Pos, Vector3 &Result)
{
    Vector3 PreviousPos;

    if (GetTickCount() >= velupd)
    {
        velupd = GetTickCount() + 100//random timer for test;

        Vector3 Diff = Pos - PreviousPos;
        float Len = sqrtf(Diff .x * Diff .x + Diff .y * Diff .y + Diff .z * Diff .z);

        if (Len >= 0.01)
        {
            Result = (Diff / Len);
        }
    }
      PreviousPos = Pos.
}

计算错误。数据仅可用对象位置(无速度等)。

Answer 1

需要更多详细信息才能为您提供更准确的答案。但我基本上看到两个问题。您没有初始化 PreviousPos 对象，在我看来您希望它持续存在，对吧？

假设Vector3类有减号(-)运算符重载，所以你可以做这个操作，你可能会这样做。

void TestVelocity(Vector3& Pos, Vector3 &Result)
{  
static Vector3 PreviousPos; //Initialize here the initial position to zero with your constructor

    if (GetTickCount() >= velupd)
    {
        velupd = GetTickCount() + 100//random timer for test;

        Vector3 Diff = Pos - PreviousPos;
        float Len = sqrtf(Diff .x * Diff .x + Diff .y * Diff .y + Diff .z * Diff .z);

        if (Len >= 0.01)
        {
            Result = (Diff / Len);
        }
    }
  PreviousPos = Pos.
}

另一种解决方案是将先前的位置作为参数，但正如我所说，如果我们不知道您想要的实现是什么，则很难判断。这些是根据需要的建议。