XMFLOAT3 HeightMapApplication::getVertexNormal(INT xPos, INT yPos) const
{
    XMFLOAT3 averagedFloat3(0.0f, 0.0f, 0.0f);
    XMVECTOR tempA, tempB;

    XMVECTOR* pVectors = nullptr;
    INT pVecSize = 0;

    auto toIndex = [](INT x, INT y, INT width)
    {
        return (x + y * width);
    };

    enum EGridPos
    {
        TopLeft,
        TopRight,
        BottomLeft,
        BottomRight,
        LeftBoundry,
        RightBoundry,
        TopBoundry,
        BottomBoundry,
        Central
    };

    EGridPos gridPos = Central;
    //determine grid state
    if (xPos == 0 || xPos == m_HeightMapWidth - 1 || yPos == 0 || yPos == m_HeightMapWidth - 1)
    {
        return averagedFloat3;
    }

    switch (gridPos)
    {

    case TopLeft:
    {
        pVecSize = 3;
        pVectors = new XMVECTOR[pVecSize];

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos + 1, yPos, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[0] = tempA - tempB;


        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos + 1, yPos + 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[1] = tempA - tempB;


        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos + 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[2] = tempA - tempB;

    }
    break;

    case TopRight:
    {
        pVecSize = 3;
        pVectors = new XMVECTOR[pVecSize];

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos - 1, yPos, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[0] = tempA - tempB;


        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos - 1, yPos + 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[1] = tempA - tempB;


        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos - 1, yPos - 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[2] = tempA - tempB;
    }
    break;

    case BottomLeft:
    {
        pVecSize = 3;
        pVectors = new XMVECTOR[pVecSize];

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos + 1, yPos, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[0] = tempA - tempB;


        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos + 1, yPos - 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[1] = tempA - tempB;


        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos - 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[2] = tempA - tempB;
    }
    break;

    case BottomRight:
    {
        pVecSize = 3;
        pVectors = new XMVECTOR[pVecSize];

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos - 1, yPos, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[0] = tempA - tempB;


        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos - 1, yPos - 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[1] = tempA - tempB;


        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos - 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[2] = tempA - tempB;
    }
    break;


    case Central:
    {
        pVecSize = 8;
        pVectors = new XMVECTOR[pVecSize];

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos + 1, yPos, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[0] = tempA - tempB;

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos + 1, yPos + 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[1] = tempA - tempB;

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos + 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[2] = tempA - tempB;

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos - 1, yPos, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[3] = tempA - tempB;

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos - 1, yPos - 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[4] = tempA - tempB;

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos - 1, yPos + 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[5] = tempA - tempB;

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos + 1, yPos, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[6] = tempA - tempB;

        tempA = XMLoadFloat3(&m_pHeightMap[toIndex(xPos + 1, yPos - 1, m_HeightMapWidth)]);
        tempB = XMLoadFloat3(&m_pHeightMap[toIndex(xPos, yPos, m_HeightMapWidth)]);
        pVectors[7] = tempA - tempB;
    }
    break;

    default: break;

    }

    XMVECTOR averagedVec;

    switch (pVecSize)
    {
    default:break;
    case 3:

        averagedVec += XMVector3Cross(pVectors[0], pVectors[1]);
        averagedVec += XMVector3Cross(pVectors[0], pVectors[2]);
        averagedVec /= 2.0f;
        break;
    case 5:
        break;
    case 8:
        for (int i = 0; i < pVecSize / 2; i += 2)
        {
            averagedVec += XMVector3Cross(pVectors[i], pVectors[i + 1]);
        }
        averagedVec /= (float)(pVecSize / 2);
        break;
    }

    XMStoreFloat3(&averagedFloat3, averagedVec);

    delete[] pVectors;

    return averagedFloat3;
}