Constant buffer not updating

Question

I'm trying to rotate models independently of each other however I cannot for the life of my figure out how. I have gotten to the stage of writing this:

std::vector<int>::size_type st = Models.size();
if (!Models.empty())
{
    for (unsigned x = 0; x < st; x++)
    {
        D3DXMATRIX matRotate;

        D3DXMatrixRotationY(&matRotate, D3DXToRadian((x + 1) * 60));

        cBuffer[x].Final = matRotate * matView * matProjection;
        cBuffer[x].Rotation = matRotate;

        devcon->UpdateSubresource(pCBuffer, 0, NULL, &cBuffer[x], 0, 0);

        devcon->VSSetShader(pVS, 0, 0);
        devcon->VSSetConstantBuffers(0, 1, &pCBuffer);
        devcon->PSSetShader(pPS, 0, 0);

        Models.at(x)->Render(devcon);       
    }
}
swapchain->Present(0, 0);

but this only updates for the first assignment of rotation. Why isn't it rotating and how do I make it? Thanks in advance.

Answer 1

Your rotation will clearly always be the same every frame. The code you wrote there just sets the rotation to one single value every frame, if this code is run every frame, that is. Instead, have a variable , say rotation_offset that will be updated each frame, and will have a scope outside this for loop you have there. You should do something like this:

`

//somewhere out side that function
float rotation_offset = 0;

/*...*/

//right before the code you posted
rotation_offset += 0.01f;  //the amount to increase rotation each frame

std::vector<int>::size_type st = Models.size();
if (!Models.empty())
{
    for (unsigned x = 0; x < st; x++)
    {
        /* ... */
        D3DXMatrixRotationY(&matRotate, D3DXToRadian((x + rotation_offset) * 60));
        /* ... */
    }
    /*...*/
}

`

And that should make things keep rotating.