New stops my object working correctly

Question

I've had to completely rewrite this problem as I've found out a lot more about it now.

Background:

My programme is drawing some 3d objects under directx11. I have a class that contains the data, pointers, and functions needed to draw the required 3d objects. Everything was working well. I could create many different 3d objects and draw them wherever I wanted. Great!

Then I needed to put them in a container and into a vector so I didn't have to create each object manually, this was where the trouble started; it would crash 1 time in 5 or so.

Unhandled exception at 0x00C308C1 in SpritesNTextN3D.exe: 0xC0000005: Access violation reading location 0xFFFFFFFF.

It crashed when using vectors and maps. I continued this line of enquiry and tried using a pointer and new:

ThreeD_Cube* threed_cube_p;
threed_cube_p = new ThreeD_Cube;

This also caused it to crash when I ran its draw function.

threed_cube_p->draw(threeD, camera, d3dContext_mp);

However if created as a standard object:

ThreeD_Cube threed_cube_;

The draw function never crashes.

threed_cube_-.draw(threeD, camera, d3dContext_mp);

Likewise, creating a pointer to threed_cube_ works as expected.

Question:

What is new doing that the default constructor isn't. Is there anything I should be looking at to resolve this problem?

Answer 1

Crash after m = XMMatrixIdentity() - aligment memory in classes?

This topic covers the answer to my problem. I eventually tracked it down to XMMATRIX causing crashes with new due to memory alignment.

Here's a shortened version of the problem:

void matrix_test_pointer()
{
    XMMATRIX* xmmatrix_p;
    xmmatrix_p = new XMMATRIX;
    *xmmatrix_p = XMMatrixIdentity(); // this is where it crashes
}

void matrix_test()
{
    XMMATRIX xmmatrix;
    xmmatrix = XMMatrixIdentity();
}

int main()
{
    string wait;

    matrix_test();
    cout << "matrix_test() completed.\n";
    matrix_test_pointer();
    cout << "matrix_test_pointer() completed.\n"; // If it does you are lucky :)

    cin >> wait;
    return 0;
}

Chances are matrix_test will complete but it will crash before pointer will complete.