Vertex Switch DX

Question

So my problem is kinda simple. I have a vertex buffer, I create it with

    pDevice->CreateVertexBuffer(
        m_dwCount * sizeof(CUSTOMVERTEX)),
        0,
        CUSTOMFVF,
        D3DPOOL_MANAGED,
        &m_pVB, NULL);

and then let's say for test purposes, I want to modify all of them and multiply them. How exactly can I lock all of them and then multiply them? I tried to lock it

    CUSTOMVERTEX* pVoid;
    pVB->Lock(0, 0, (void**)&pVoid, 0);

but that I assume doesn't lock the entire buffer. I'm kinda new to the DirectX so I'm sorry if the question is too stupid, however thanks anyone for help.

Answer 1

First create your multiplied vertices (for example called newVertices). Then you need to lock your vertex buffer and get the pointer to pointer of current vertices like this :

CUSTOMVERTEX* pVertices;
HRESULT hr = m_pVB->Lock(0, 0, reinterpret_cast<void**>(&pVertices), 0);

Then you can use memcpy to replace your new vertices into it like this :

if(hr == S_OK)
    memcpy(pVertices, newVertices, num_of_vertices * sizeof(CUSTOMVERTEX));

Then unlock you vertex buffer like this :

hr = m_pVB->Unlock();