Как динамически изменить цвет треугольника в directx11 из туториала?

//--------------------------------------------------------------------------------------
// Create Direct3D device and swap chain
//--------------------------------------------------------------------------------------
HRESULT InitDevice()
{
  HRESULT hr = S_OK;

  RECT rc;
  GetClientRect(g_hWnd, &rc);
  UINT width = rc.right - rc.left;
  UINT height = rc.bottom - rc.top;

  UINT createDeviceFlags = 0;
#ifdef _DEBUG
  createDeviceFlags |= D3D11_CREATE_DEVICE_DEBUG;
#endif

  D3D_DRIVER_TYPE driverTypes[] =
  {
    D3D_DRIVER_TYPE_HARDWARE,
    D3D_DRIVER_TYPE_WARP,
    D3D_DRIVER_TYPE_REFERENCE,
  };
  UINT numDriverTypes = ARRAYSIZE(driverTypes);

  D3D_FEATURE_LEVEL featureLevels[] =
  {
    D3D_FEATURE_LEVEL_11_0,
    D3D_FEATURE_LEVEL_10_1,
    D3D_FEATURE_LEVEL_10_0,
  };
  UINT numFeatureLevels = ARRAYSIZE(featureLevels);

  DXGI_SWAP_CHAIN_DESC sd;
  ZeroMemory(&sd, sizeof(sd));
  sd.BufferCount = 1;
  sd.BufferDesc.Width = width;
  sd.BufferDesc.Height = height;
  sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
  sd.BufferDesc.RefreshRate.Numerator = 60;
  sd.BufferDesc.RefreshRate.Denominator = 1;
  sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
  sd.OutputWindow = g_hWnd;
  sd.SampleDesc.Count = 1;
  sd.SampleDesc.Quality = 0;
  sd.Windowed = TRUE;

  for (UINT driverTypeIndex = 0; driverTypeIndex < numDriverTypes; driverTypeIndex++)
  {
    g_driverType = driverTypes[driverTypeIndex];
    hr = D3D11CreateDeviceAndSwapChain(NULL, g_driverType, NULL, createDeviceFlags, featureLevels, numFeatureLevels,
      D3D11_SDK_VERSION, &sd, &g_pSwapChain, &g_pd3dDevice, &g_featureLevel, &g_pImmediateContext);
    if (SUCCEEDED(hr))
      break;
  }
  if (FAILED(hr))
    return hr;

  // Create a render target view
  ID3D11Texture2D* pBackBuffer = NULL;
  hr = g_pSwapChain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&pBackBuffer);
  if (FAILED(hr))
    return hr;

  hr = g_pd3dDevice->CreateRenderTargetView(pBackBuffer, NULL, &g_pRenderTargetView);
  pBackBuffer->Release();
  if (FAILED(hr))
    return hr;

  g_pImmediateContext->OMSetRenderTargets(1, &g_pRenderTargetView, NULL);

  // Compile the vertex shader
  ID3DBlob* pVSBlob = NULL;
  hr = CompileShaderFromFile(L"Tutorial02.fx", "VS", "vs_4_0", &pVSBlob);
  if (FAILED(hr))
  {
    MessageBox(NULL,
      L"The FX file cannot be compiled.  Please run this executable from the directory that contains the FX file.", L"Error", MB_OK);
    return hr;
  }

  // Create the vertex shader
  hr = g_pd3dDevice->CreateVertexShader(pVSBlob->GetBufferPointer(), pVSBlob->GetBufferSize(), NULL, &g_pVertexShader);
  if (FAILED(hr))
  {
    pVSBlob->Release();
    return hr;
  }

  // Define the input layout
  D3D11_INPUT_ELEMENT_DESC layout[] =
  {
    { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
  };
  UINT numElements = ARRAYSIZE(layout);

  // Create the input layout
  hr = g_pd3dDevice->CreateInputLayout(layout, numElements, pVSBlob->GetBufferPointer(),
    pVSBlob->GetBufferSize(), &g_pVertexLayout);
  pVSBlob->Release();
  if (FAILED(hr))
    return hr;

  // Set the input layout
  g_pImmediateContext->IASetInputLayout(g_pVertexLayout);

  // Compile the pixel shader
  ID3DBlob* pPSBlob = NULL;
  hr = CompileShaderFromFile(L"Tutorial02.fx", "PS", "ps_4_0", &pPSBlob);
  if (FAILED(hr))
  {
    MessageBox(NULL,
      L"The FX file cannot be compiled.  Please run this executable from the directory that contains the FX file.", L"Error", MB_OK);
    return hr;
  }

  // Create the pixel shader
  hr = g_pd3dDevice->CreatePixelShader(pPSBlob->GetBufferPointer(), pPSBlob->GetBufferSize(), NULL, &g_pPixelShader);
  pPSBlob->Release();
  if (FAILED(hr))
    return hr;

  // Create vertex buffer
  SimpleVertex vertices[] =
  {
    XMFLOAT3(0.0f, 0.5f, 0.5f),
    XMFLOAT3(0.5f, -0.5f, 0.5f),
    XMFLOAT3(-0.5f, -0.5f, 0.5f),
  };
  D3D11_BUFFER_DESC bd;
  ZeroMemory(&bd, sizeof(bd));
  bd.Usage = D3D11_USAGE_DEFAULT;
  bd.ByteWidth = sizeof(SimpleVertex) * 3;
  bd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
  bd.CPUAccessFlags = 0;
  D3D11_SUBRESOURCE_DATA InitData;
  ZeroMemory(&InitData, sizeof(InitData));
  InitData.pSysMem = vertices;
  hr = g_pd3dDevice->CreateBuffer(&bd, &InitData, &g_pVertexBuffer);
  if (FAILED(hr))
    return hr;

  // Set vertex buffer
  UINT stride = sizeof(SimpleVertex);
  UINT offset = 0;
  g_pImmediateContext->IASetVertexBuffers(0, 1, &g_pVertexBuffer, &stride, &offset);

  // Setup the viewport
  D3D11_VIEWPORT vp;
  vp.Width = (FLOAT)width;
  vp.Height = (FLOAT)height;
  vp.MinDepth = 0.0f;
  vp.MaxDepth = 1.0f;
  vp.TopLeftX = 0;
  vp.TopLeftY = 0;
  g_pImmediateContext->RSSetViewports(1, &vp);

  // Set primitive topology
  g_pImmediateContext->IASetPrimitiveTopology(D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST);

  return S_OK;
}

  D3D11_INPUT_ELEMENT_DESC layout[] =
  {
    { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT,    0, 0,                            D3D11_INPUT_PER_VERTEX_DATA, 0 },
    { "COLOR"   , 1, DXGI_FORMAT_R32G32B32A32_FLOAT, 0, D3D11_APPEND_ALIGNED_ELEMENT, D3D11_INPUT_PER_VERTEX_DATA, 0 }
  };

  D3D11_INPUT_ELEMENT_DESC layout[] =
  {
    { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT,    0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },

    { "COLOR"   , 0, DXGI_FORMAT_R32G32B32A32_FLOAT, 1, 0, D3D11_INPUT_PER_VERTEX_DATA, 1 }
  };