DirectX11 C++ Shader Buffer becomes null on polygon layout description - c++

Question

I am developing a game engine using DX11. My problem is that I am getting a read access violation because vertexShaderBuffer was nullptr.
bool TerrainShaderClass::InitializeShader(ID3D11Device* device, HWND hwnd, LPCSTR vsFileName, LPCSTR psFileName)
{
HRESULT result;
ID3D10Blob* errorMessage = nullptr;
ID3D10Blob* vertexShaderBuffer = nullptr;
ID3D10Blob* pixelShaderBuffer = nullptr;
D3D11_INPUT_ELEMENT_DESC polygonLayout[3];
unsigned int numElements;
D3D11_SAMPLER_DESC samplerDesc;
D3D11_BUFFER_DESC matrixBufferDesc;
D3D11_BUFFER_DESC lightBufferDesc;
result = D3DX11CompileFromFile(vsFileName, NULL, NULL, "TerrainVertexShader", "vs_5_0", D3D10_SHADER_ENABLE_STRICTNESS, 0, NULL,
&vertexShaderBuffer, &errorMessage, NULL);
if (FAILED(result))
{
if (errorMessage)
{
OutputShaderErrorMessage(errorMessage, hwnd, vsFileName);
}
else
{
MessageBox(hwnd, vsFileName, "Missing Shader File", MB_OK);
}
return false;
}
result = D3DX11CompileFromFile(psFileName, NULL, NULL, "TerrainPixelShader", "ps_5_0", D3D10_SHADER_ENABLE_STRICTNESS, 0, NULL,
&pixelShaderBuffer, &errorMessage, NULL);
if (FAILED(result))
{
if (errorMessage)
{
OutputShaderErrorMessage(errorMessage, hwnd, psFileName);
}
else
{
MessageBox(hwnd, psFileName, "Missing Shader File", MB_OK);
}
return false;
}
result = device->CreateVertexShader(vertexShaderBuffer->GetBufferPointer(), vertexShaderBuffer->GetBufferSize(), NULL,
&m_vertexShader);
if (FAILED(result))
{
return false;
}
result = device->CreatePixelShader(pixelShaderBuffer->GetBufferPointer(), pixelShaderBuffer->GetBufferSize(), NULL,
&m_pixelShader);
if (FAILED(result))
{
return false;
}
// This setup needs to match the VertexType stucture in the ModelClass and in the shader.
polygonLayout[0].SemanticName = "POSITION";
polygonLayout[0].SemanticIndex = 0;
polygonLayout[0].Format = DXGI_FORMAT_R32G32B32_FLOAT;
polygonLayout[0].InputSlot = 0;
polygonLayout[0].AlignedByteOffset = 0;
polygonLayout[0].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
polygonLayout[0].InstanceDataStepRate = 0;
polygonLayout[1].SemanticName = "TEXCOORD";
polygonLayout[1].SemanticIndex = 0;
polygonLayout[1].Format = DXGI_FORMAT_R32G32_FLOAT;
polygonLayout[1].InputSlot = 0;
polygonLayout[1].AlignedByteOffset = D3D11_APPEND_ALIGNED_ELEMENT;
polygonLayout[1].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
polygonLayout[1].InstanceDataStepRate = 0;
polygonLayout[2].SemanticName = "NORMAL";
polygonLayout[2].SemanticIndex = 0;
polygonLayout[2].Format = DXGI_FORMAT_R32G32B32_FLOAT;
polygonLayout[2].InputSlot = 0;
polygonLayout[2].AlignedByteOffset = D3D11_APPEND_ALIGNED_ELEMENT;
polygonLayout[2].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
polygonLayout[2].InstanceDataStepRate = 0;
polygonLayout[3].SemanticName = "COLOR";
polygonLayout[3].SemanticIndex = 0;
polygonLayout[3].Format = DXGI_FORMAT_R32G32B32_FLOAT;
polygonLayout[3].InputSlot = 0;
polygonLayout[3].AlignedByteOffset = D3D11_APPEND_ALIGNED_ELEMENT;
polygonLayout[3].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;
polygonLayout[3].InstanceDataStepRate = 0;
numElements = sizeof(polygonLayout) / sizeof(polygonLayout[0]);
result = device->CreateInputLayout(polygonLayout, numElements, vertexShaderBuffer->GetBufferPointer(),
vertexShaderBuffer->GetBufferSize(), &m_layout);
if (FAILED(result))
{
return false;
}
vertexShaderBuffer->Release();
vertexShaderBuffer = nullptr;
pixelShaderBuffer->Release();
pixelShaderBuffer = nullptr;
//Continues
When the code reaches polygonLayout[3].InputSlotClass = D3D11_INPUT_PER_VERTEX_DATA;, the buffer is set as normal. But after that line ( polygonLayout[3].InstanceDataStepRate = 0;) the value goes null for no appearant reason, with the
result = device->CreateInputLayout(polygonLayout, numElements, vertexShaderBuffer->GetBufferPointer(),
vertexShaderBuffer->GetBufferSize(), &m_layout);
line throwing the exception.
I tried searching online with no results. Any help is much appreciated. Thanks in advance.

Answer 1

polygonLayout array contains only 3 items so when you fill polygonLayout[3] you are producing buffer overrun and face Undefined Behavior (potentially corrupting other variables stored on the stack). It would be a good idea to 1) make it contain 4 items; 2) use array wrapper with (debug) indexing check:
::std::array<D3D11_INPUT_ELEMENT_DESC, 4> polygonLayout;