Tutorial 5: 3D Transformation

D3D中，变换就是通过和一个变换矩阵相乘来执行的。

D3D中有3中基本的图元变换方式：

平移translation (where it lies in space relative to the origin)：

　　XMMatrixTranslation

　　XMMatrixTranslationFromVector

旋转rotation (its direction in relation to the x, y, z frame)：

　　XMMatrixRotationX

　　XMMatrixRotationY

　　XMMatrixRotationZ

　　XMMatrixRotationAxis

缩放scaling (its distance from origin)：

　　XMMatrixRotationAxis

复杂的运动（变换）都可以用以上基本变换复合而成。

深度缓存的使用：(深度缓存就是一个2D texture，所以我们使用CreateTexture2D来创建深度缓存)

    ID3D11Texture2D*        g_pDepthStencil = NULL;

    ID3D11DepthStencilView* g_pDepthStencilView = NULL;

    // Create depth stencil texture创建深度模板纹理

    D3D11_TEXTURE2D_DESC descDepth;

    ZeroMemory( &descDepth, sizeof(descDepth) );

    descDepth.Width = width;

    descDepth.Height = height;

    descDepth.MipLevels = 1;

    descDepth.ArraySize = 1;

    descDepth.Format = DXGI_FORMAT_D24_UNORM_S8_UINT; //A 32-bit z-buffer format that uses 24 bits for the depth channel and 8 bits for the stencil 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 //channel.

    descDepth.SampleDesc.Count = 1;

    descDepth.SampleDesc.Quality = 0;

    descDepth.Usage = D3D11_USAGE_DEFAULT;

    descDepth.BindFlags = D3D11_BIND_DEPTH_STENCIL;

    descDepth.CPUAccessFlags = 0;

    descDepth.MiscFlags = 0;

    hr = g_pd3dDevice->CreateTexture2D( &descDepth, NULL, &g_pDepthStencil );

    if( FAILED( hr ) )

        return hr;

 

    // Create the depth stencil view创建深度模板视图

    D3D11_DEPTH_STENCIL_VIEW_DESC descDSV;

     ZeroMemory( &descDSV, sizeof(descDSV) );

    descDSV.Format = descDepth.Format;

    descDSV.ViewDimension = D3D11_DSV_DIMENSION_TEXTURE2D;//The resource will be accessed as a 2D texture.

    descDSV.Texture2D.MipSlice = 0;

    hr = g_pd3dDevice->CreateDepthStencilView( g_pDepthStencil, &descDSV, &g_pDepthStencilView );

    if( FAILED( hr ) )

        return hr;

 

     //将render targets和depth-stencil buffer绑定到设备的Output-merger state

    g_pImmediateContext->OMSetRenderTargets(1, &g_pRenderTargetView, g_pDepthStencilView);

 

    //每一帧render之前，需要清空深度模板视图 Clear the depth buffer to 1.0 (max depth)

    g_pImmediateContext->ClearDepthStencilView( g_pDepthStencilView, D3D11_CLEAR_DEPTH, 1.0f, 0 );