D3D11顶点纹理创建

在函数gs_vertex_buffer::BuildBuffers()中除了创建顶点坐标外，也有其它相关的坐标创建，但也有一个特殊的就是纹理坐标的创建。

void gs_vertex_buffer::BuildBuffers()
{
    InitBuffer(sizeof(vec3), vbd.data->num, vbd.data->points, &vertexBuffer);

    if (vbd.data->normals)
        InitBuffer(sizeof(vec3), vbd.data->num, vbd.data->normals,&normalBuffer);

    if (vbd.data->tangents)
        InitBuffer(sizeof(vec3), vbd.data->num, vbd.data->tangents,&tangentBuffer);

    if (vbd.data->colors)
        InitBuffer(sizeof(uint32_t), vbd.data->num, vbd.data->colors,&colorBuffer);

    for (size_t i = 0; i < vbd.data->num_tex; i++) {
        struct gs_tvertarray *tverts = vbd.data->tvarray + i;

        if (tverts->width != 2 && tverts->width != 4)
            throw "Invalid texture vertex size specified";
        if (!tverts->array)
            throw "No texture vertices specified";

        ComPtr<ID3D11Buffer> buffer;
        InitBuffer(tverts->width * sizeof(float), vbd.data->num,tverts->array, &buffer);

        uvBuffers.push_back(buffer);
        uvSizes.push_back(tverts->width * sizeof(float));
    }
}

纹理坐析的创建和顶点坐标一样，都是使用的函数InitBuffer实现的。
InitBuffer函数创建了：

• 顶点坐标 ComPtr<ID3D11Buffer> vertexBuffer
• 法线 ComPtr<ID3D11Buffer> normalBuffer
• 正切 ComPtr<ID3D11Buffer> tangentBuffer
• 颜色 ComPtr<ID3D11Buffer> colorBuffer
• 纹理向量 vector<ComPtr<ID3D11Buffer>> uvBuffers

void gs_vertex_buffer::InitBuffer(const size_t elementSize,
                  const size_t numVerts, void *array,
                  ID3D11Buffer **buffer)
{
    D3D11_BUFFER_DESC bd;
    D3D11_SUBRESOURCE_DATA srd;
    HRESULT hr;

    memset(&bd, 0, sizeof(bd));
    memset(&srd, 0, sizeof(srd));

    bd.Usage = dynamic ? D3D11_USAGE_DYNAMIC : D3D11_USAGE_DEFAULT;
    bd.CPUAccessFlags = dynamic ? D3D11_CPU_ACCESS_WRITE : 0;
    bd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
    bd.ByteWidth = UINT(elementSize * numVerts);
    srd.pSysMem = array;

    hr = device->device->CreateBuffer(&bd, &srd, buffer);
    if (FAILED(hr))
        throw HRError("Failed to create buffer", hr);
}