将c#结构编组到DX11缓存中

我有一些问题(我认为)在c#中包装我的结构并将它们传递给我在hsl中注册的缓冲区。当我以一种方式包装我的结构时，信息似乎能够传递到着色器:

[StructLayout(LayoutKind.Explicit, Size = 16)]
internal struct TestStruct
{
    [FieldOffset(0)]
    public Vector3 mEyePosition;
    [FieldOffset(12)]
    public int type;
}

当我创建这个结构体并将其设置为c#中的常量缓冲区时，它似乎工作得很好。我得到了我期望的颜色:

cbuffer PerFrame : register(b0)
{
    Vector3 eyePos;
    int type;
}
float3 GetColour()
{
    float3 returnColour = float(0.0f, 0.0f, 0.0f);
    switch(type)
    {
        case 0:
            returnColour = float3(1.0f, 0.0f, 0.0f);
            break;
        case 1:
            returnColour = float3(0.0f, 1.0f, 0.0f);
            break;
        case 2:
            returnColour = float3(0.0f, 0.0f, 1.0f);
            break;
    }
    return returnColour;
}

但是当我使用另一个结构体将结构体更改为结构体时，它似乎设置正确。请注意，内部结构将包含额外的信息，但我正试图尽可能地简化它:

[StructLayout(Layout.Explicit, Size = 16)] //Note this is 16 because HLSL packs in 4 float 'chunks'
internal struct InternalTestStruct
{
    [FieldOffset(0)]
    public int type;
}
[StructLayout(LayoutKind.Explicit, Size = 32)]
internal struct TestStruct
{
    [FieldOffset(0)]
    public Vector3 mEyePosition;
    //Missing 4 bytes here for correct packing.
    [FieldOffset(16)]
    public InternalTestStruct internal;
}

在HLSL

struct InternalType
{
    int type;
}
cbuffer PerFrame : register(b0)
{
    Vector3 eyePos;
    InternalType internalStruct;
}
float3 GetColour()
{
    float3 returnColour = float(0.0f, 0.0f, 0.0f);
    switch(internaltype.type)
    {
        case 0:
            returnColour = float3(1.0f, 0.0f, 0.0f);
            break;
        case 1:
            returnColour = float3(0.0f, 1.0f, 0.0f);
            break;
        case 2:
            returnColour = float3(0.0f, 0.0f, 1.0f);
            break;
    }
    return returnColour;
}

你认为我包装结构的方式有问题吗?或者问题可能在其他地方，我只认为这是我的包装，因为当我用TestStruct设置常量缓冲区时，我可以得到第一个例子，但一旦我将其扩展到包括InternalTestStruct，它似乎不起作用。

请帮忙就太好了。

struct InternalType
{
    int type;
}
cbuffer PerFrame : register(b0)
{
    float3 eyePos;
    InternalType internalStruct;
} 

cbuffer PerFrame : register(b0)
{
    float3 eyePos;
    int dummy; //Here you need to force the padding
    InternalType internalStruct;
}