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