Directx教程(30) 如何保证渲染物体不会变形

原文:Directx教程(30) 如何保证渲染物体不会变形

     在Directx11教程(6)中, 我们曾经实现过这个功能，但那时是在SystemClass中，处理WM_SIZE时候，重新调用m_Graphics的初始化函数，这样的话，它的成员变量D3D类还有其它几个成员类，都会重新创建，所以我们的场景等于是从头重新渲染。对于静态场景，这没有问题，但是对于动画场景，我们一改变窗口大小，动画就会从头播放，这显然不是我们所希望的。

     本章中，我们在D3DClass类中新建一个函数，每次改变窗口大小时候，我们就改变framebuffer大小，然后重新建立目标渲染视图、深度模版视图等等。代码是在myTutorialD3D_23的基础上改写的。

    

最关键的代码就是这一行：

m_swapChain->ResizeBuffers(1, screenWidth, screenHeight, DXGI_FORMAT_R8G8B8A8_UNORM, 0);

D3Class类中增加的函数为：

bool D3DClass::ResizeBuffer(int screenWidth, int screenHeight)
    {
   
    HRESULT result;

    //交换链为空直接返回
    if(!m_swapChain)
        return false;

    //窗口最小化时候为0，会创建缓冲失败
    if(screenHeight < 1)
        screenHeight = 1;
    if(screenWidth < 1)
        screenWidth = 1;

    if(m_renderTargetView)
        {
        m_renderTargetView->Release();
        m_renderTargetView = 0;
        }
    if(m_depthStencilView)
        {
        m_depthStencilView->Release();
        m_depthStencilView = 0;
        }

    if(m_depthStencilBuffer)
        {
        m_depthStencilBuffer->Release();
        m_depthStencilBuffer = 0;
        }

    //改变交换链中后后缓冲大小后，重新创建渲染目标视图
    result = m_swapChain->ResizeBuffers(1, screenWidth, screenHeight, DXGI_FORMAT_R8G8B8A8_UNORM, 0);
    if(FAILED(result))
        {
        HR(result);
        return false;
        }
    // 得到交换链中的后缓冲指针.
    ID3D11Texture2D* backBufferPtr;
    result = m_swapChain->GetBuffer(0, __uuidof(ID3D11Texture2D), (LPVOID*)&backBufferPtr);
    if(FAILED(result))
        {
        HR(result);
        return false;
        }

    // 用后缓冲创建渲染目标视图.
    result = m_device->CreateRenderTargetView(backBufferPtr, NULL, &m_renderTargetView);
    if(FAILED(result))
        {
        HR(result);
        return false;
        }

    //释放后缓冲.(引用计数减1)
    backBufferPtr->Release();
    backBufferPtr = 0;

    D3D11_TEXTURE2D_DESC depthBufferDesc;
    D3D11_DEPTH_STENCIL_DESC depthStencilDesc;
    D3D11_DEPTH_STENCIL_VIEW_DESC depthStencilViewDesc;
    D3D11_RASTERIZER_DESC rasterDesc;
    D3D11_VIEWPORT viewport;
    //创建深度模版视图
    // 初始化深度缓冲描述.
    // 初始化深度缓冲描述.
    ZeroMemory(&depthBufferDesc, sizeof(depthBufferDesc));

    //设置深度缓冲描述
    depthBufferDesc.Width = screenWidth;
    depthBufferDesc.Height = screenHeight;
    depthBufferDesc.MipLevels = 1;  //对于深度缓冲为1
    depthBufferDesc.ArraySize = 1;  //对于深度缓冲为1，对于纹理，这2个参数有更多用途
    depthBufferDesc.Format = DXGI_FORMAT_D24_UNORM_S8_UINT;
    depthBufferDesc.SampleDesc.Count = 1;
    depthBufferDesc.SampleDesc.Quality = 0;
    depthBufferDesc.Usage = D3D11_USAGE_DEFAULT;
    depthBufferDesc.BindFlags = D3D11_BIND_DEPTH_STENCIL;
    depthBufferDesc.CPUAccessFlags = 0;
    depthBufferDesc.MiscFlags = 0;

    // 创建深度缓冲.
    result = m_device->CreateTexture2D(&depthBufferDesc, NULL, &m_depthStencilBuffer);
    if(FAILED(result))
        {
        HR(result);
        return false;

        }

    // 初始化深度模版状态描述.
    ZeroMemory(&depthStencilDesc, sizeof(depthStencilDesc));

   // 设置深度模版状态描述.
    depthStencilDesc.DepthEnable = true;
    depthStencilDesc.DepthWriteMask = D3D11_DEPTH_WRITE_MASK_ALL;//D3D11_DEPTH_WRITE_MASK_ZERO禁止写深度缓冲
    depthStencilDesc.DepthFunc = D3D11_COMPARISON_LESS;

    depthStencilDesc.StencilEnable = true;
    depthStencilDesc.StencilReadMask = 0xFF;
    depthStencilDesc.StencilWriteMask = 0xFF;

    // 对于front face 像素使用的模版操作操作.
    depthStencilDesc.FrontFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;
    depthStencilDesc.FrontFace.StencilDepthFailOp = D3D11_STENCIL_OP_INCR;
    depthStencilDesc.FrontFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;
    depthStencilDesc.FrontFace.StencilFunc = D3D11_COMPARISON_ALWAYS;

    // 对于back face像素使用的模版操作模式.
    depthStencilDesc.BackFace.StencilFailOp = D3D11_STENCIL_OP_KEEP;
    depthStencilDesc.BackFace.StencilDepthFailOp = D3D11_STENCIL_OP_DECR;
    depthStencilDesc.BackFace.StencilPassOp = D3D11_STENCIL_OP_KEEP;
    depthStencilDesc.BackFace.StencilFunc = D3D11_COMPARISON_ALWAYS;

    // 创建深度模版状态，使其生效
    result = m_device->CreateDepthStencilState(&depthStencilDesc, &m_depthStencilState);
    if(FAILED(result))
        {
        HR(result);
        return false;

        }

   // 设置深度模版状态.
    m_deviceContext->OMSetDepthStencilState(m_depthStencilState, 1);

    // 初始化深度模版视图.
    ZeroMemory(&depthStencilViewDesc, sizeof(depthStencilViewDesc));

    // 设置深度模版视图描述.
    depthStencilViewDesc.Format = DXGI_FORMAT_D24_UNORM_S8_UINT;
    depthStencilViewDesc.ViewDimension = D3D11_DSV_DIMENSION_TEXTURE2D;
    depthStencilViewDesc.Texture2D.MipSlice = 0;

    // 创建深度模版视图.
    result = m_device->CreateDepthStencilView(m_depthStencilBuffer, &depthStencilViewDesc, &m_depthStencilView);
    if(FAILED(result))
        {
        HR(result);
        return false;
        }

   // 绑定渲染目标视图和深度缓冲到渲染管线.
    m_deviceContext->OMSetRenderTargets(1, &m_renderTargetView, m_depthStencilView);

    // 设置光栅化描述，指定多边形如何被渲染.
    rasterDesc.AntialiasedLineEnable = false;
    rasterDesc.CullMode = D3D11_CULL_BACK;
    rasterDesc.DepthBias = 0;
    rasterDesc.DepthBiasClamp = 0.0f;
    rasterDesc.DepthClipEnable = true;
    rasterDesc.FillMode = D3D11_FILL_SOLID; //D3D11_FILL_SOLID
    rasterDesc.FrontCounterClockwise = false;
    rasterDesc.MultisampleEnable = false;
    rasterDesc.ScissorEnable = false;
    rasterDesc.SlopeScaledDepthBias = 0.0f;

    // 创建光栅化状态
    result = m_device->CreateRasterizerState(&rasterDesc, &m_rasterState);
    if(FAILED(result))
        {
        HR(result);
        return false;
        }

    //设置光栅化状态，使其生效
    m_deviceContext->RSSetState(m_rasterState);

    // 设置视口，显示全部后缓冲内容
    viewport.Width = (float)screenWidth;
    viewport.Height = (float)screenHeight;
    viewport.MinDepth = 0.0f;
    viewport.MaxDepth = 1.0f;
    viewport.TopLeftX = 0.0f;
    viewport.TopLeftY = 0.0f;

    // 创建视口
    m_deviceContext->RSSetViewports(1, &viewport);

    }

// 设置透视投影矩阵
fieldOfView = (float)D3DX_PI / 4.0f;
screenAspect = (float)screenWidth / (float)screenHeight;

// 创建透视投影矩阵.
D3DXMatrixPerspectiveFovLH(&m_projectionMatrix, fieldOfView, screenAspect, m_screenNear, m_screenDepth);

//初始化world矩阵为单位矩阵.
//该矩阵实现局部坐标到世界坐标的转换
D3DXMatrixIdentity(&m_worldMatrix);

// 创建正交投影矩阵，主要用来实施2D渲染.
D3DXMatrixOrthoLH(&m_orthoMatrix, (float)screenWidth, (float)screenHeight, m_screenNear, m_screenDepth);

    注意：m_screenNear,m_screenDepth是D3DClass增加的两个成员变量，在初始化函数中，它们被用来保存screenNear和screenDetph。

   另外一点小变动就是在GraphicsClass中把m_D3D设置为public，还有就是SystemClass中

if(m_Graphics)
    {
    bool result = m_Graphics->m_D3D->ResizeBuffer(screenWidth, screenHeight);
    if(!result)
        {
        return false;
        }
    }

完整的代码请参考：

工程文件myTutorialD3D11_26

代码下载：

http://files.cnblogs.com/mikewolf2002/myTutorialD3D11_26.zip