CODEWITHSUNDEEP
c++directxgame-engine
aPlutonicCoder
aPlutonicCoder

Reputation: 116

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

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.

Upvotes: 1

Views: 137

Answers (1)

user7860670
user7860670

Reputation: 37549

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;

Upvotes: 3

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