Question

i’m struggling and trying to understand why the following code is not working.

I have 3 classes defined as:

class VertexType
{
public:
    VertexType(void) { };
    virtual ~VertexType() = 0;
};

class PositionColorVertex
    : public VertexType
{
public:
    PositionColorVertex(XMFLOAT3 _position, XMFLOAT4 _color)
    :Position(_position), Color(_color)
    {};
    ~PositionColorVertex() {};

    static const UINT size = 28;

    XMFLOAT3 Position;
    XMFLOAT4 Color;
};

class PositionVertex
    : public VertexType
{
public:
    PositionVertex(XMFLOAT3 _position)
    :Position(_position)
    {};
    ~PositionVertex() {};

    static const UINT size = 12;

    XMFLOAT3 Position;
};

The array initialization is working for:

PositionVertex vertices[] = { XMFLOAT3(0,0,0) };

but when i try to initialize with:

PositionColorVertex vertices[] = {
{ XMFLOAT3(0,0,0), XMFLOAT4(0,0,0,1) } };

i get an error C2552 non-aggregates cannot be initialized with initializer list.

Why PositionVertex is working whereas PositionColorVertex isn’t ?

Answer 1

Why PositionVertex is working whereas PositionColorVertex isn’t ?

Because in the first case you are initializing an array, which is an aggregate:

PositionVertex vertices[] = { XMFLOAT3(0,0,0) };

In the second case, you are attempting to initialize a PositionVertexColor with an initializer list containing two elements, then use that to initialize a size-1 array. The first part only works in C++11. You can visualize it better by splitting this:

PositionVertexColor vertices[] = { {XMFLOAT3(0,0,0), XMFLOAT4(0,0,0,1)} };

into two:

PositionVertexColor pvc =  {XMFLOAT3(0,0,0), XMFLOAT4(0,0,0,1)}; // Error, non-aggregate.
PositionVertexColor vertices[] = { pvc }; // would be OK if first step had worked