Direct3D 11教程6:光照

原文地址:http://msdn.microsoft.com/en-us/library/ff729723.aspx。

概览

在前面的教程中,因为所有物体都是以相同的方式被光照亮,因此还不够真实。本教程将介绍简单的光照概念以及如何施加光照,这个技术将使用Lambert光照模型。

这个教程的会在前一个示例的基础上包含一个光源,光源链接在轨道运行的立方体上,光照的效果可以在中央立方体表面上看到。

图6.1

源代码

(SDK root)\Samples\C++\Direct3D11\Tutorials\Tutorial06

光照

在本教程中将介绍最简单的光照类型:Lambert光照。Lambert光照具有相同的光照强度而不考虑离开光源的距离。当光照射到表面时,反射光的强度根据光在表面上的入射角大小进行计算。当光线垂直射向表面,反射回所有光照,具有最大的光强。当入射角变大时,光的强度也会减弱。

要计算表面的光照强度,必须计算光照方向和表面法线之间的夹角。法线定义为垂直于平面的一个矢量,角度的计算只需使用一个简单的点乘即可,返回的结果是光照方向矢量在法线上的投影长度。入射角越大,投影长度越短,这样,我们就有一个正确的方法调整漫反射光照。

Lambert光照

本教程使用的光源接近于单向光,表示光源的矢量决定了光线的方向。因为这是一个近似,所以物体的位置无关紧要,我们认为光照方向都是一样的。这种光源的一个例子就是太阳,在一个场景中,太阳光总是被认为是同一方向的。

另一种类型的光源是点光源,从光源中心发出光线;还有一种是聚光灯,它发出的光线具有方向性但又不是均匀照射所有物体。

初始化光照

在本教程中,我们使用两个光源。一个静止放置在立方体的上后方,另一个绕着它旋转。

因为光照是由shader进行计算的,所以必须首先声明变量然后将它们与technique绑定。在本例中,我们只需光照方向和颜色值。第一个光源为灰色不移动,第二个是一个沿轨道绕行的红色光源。

// 设置光源参数
XMFLOAT4 vLightDirs[2] =
{
    XMFLOAT4( -0.577f, 0.577f, -0.577f, 1.0f ),
    XMFLOAT4( 0.0f, 0.0f, -1.0f, 1.0f ),
};
XMFLOAT4 vLightColors[2] =
{
    XMFLOAT4( 0.5f, 0.5f, 0.5f, 1.0f ),
    XMFLOAT4( 0.5f, 0.0f, 0.0f, 1.0f )
};

第二个光源还像上一个教程中的立方体那样旋转,施加的矩阵会改变光照方向,让光照总是朝向中心。注意,XMVec3Transform方法用来在矢量上乘以矩阵。在前面的教程中,我们只是将变换矩阵乘进世界矩阵中,然后传递到shader用于变换;但本例中基于简化的考虑,我们在CPU中对光源进行世界变换。

// 使第2个正方体绕原点旋转
// Rotate the second light around the origin
XMMATRIX mRotate = XMMatrixRotationY( -2.0f * t );
XMVECTOR vLightDir = XMLoadFloat4( &vLightDirs[1] );
vLightDir = XMVector3Transform( vLightDir, mRotate );
XMStoreFloat4( &vLightDirs[1], vLightDir );

光照方向和颜色都传递到shader中,对应的变量被调用并设置,参数被传递。

//
// 更新矩阵和光源变量
//
ConstantBuffer cb1;
cb1.mWorld = XMMatrixTranspose( g_World );
cb1.mView = XMMatrixTranspose( g_View );
cb1.mProjection = XMMatrixTranspose( g_Projection );
cb1.vLightDir[0] = vLightDirs[0];
cb1.vLightDir[1] = vLightDirs[1];
cb1.vLightColor[0] = vLightColors[0];
cb1.vLightColor[1] = vLightColors[1];
cb1.vOutputColor = XMFLOAT4(0, 0, 0, 0);
g_pImmediateContext->UpdateSubresource( g_pConstantBuffer, 0, NULL, &cb1, 0, 0 );

在像素着色器中绘制光照

设置了所有数据我们就可以计算每一个像素的lambert光照因子了,使用的是上面提到过的点乘规则。

有了点乘结果后,就可以将这个结果乘以光照颜色计算光照的影响了。这个值被传递到saturate方法,这个方法将结果限定在[0,1]区间。最后,两个光源的效果会相加获得最终的像素颜色。

物体表面材质并没有考虑在光照计算中,表面的最终颜色只包含光照颜色。

//
// Pixel Shader
//
float4 PS( PS_INPUT input) : SV_Target
{
    float4 finalColor = 0;
    
    //对两个光源进行NdotL光照计算
    for(int i=0; i<2; i++)
    {
        finalColor += saturate( dot( (float3)vLightDir[i],input.Norm) * vLightColor[i] );
    }
    return finalColor;
}

经过像素着色器的处理,像素的颜色就被光照调制,你可以在中央立方体表面看到光照效果。因为本例中同一表面的法线方向相同,所以同一表面的光照强度相同。漫反射(Diffuse)光照是一个非常简单容易的光照模型,你可以使用更复杂的光照模型实现更加真实的效果。

完整代码

#include <windows.h>
#include <d3d11.h>
#include <d3dcompiler.h>
#include <directxmath.h>
#include "resource.h"

using namespace DirectX;

//--------------------------------------------------------------------------------------
// 顶点结构
//--------------------------------------------------------------------------------------
struct SimpleVertex
{
    XMFLOAT3 Pos;
    XMFLOAT3 Normal;
};


struct ConstantBuffer
{
	XMMATRIX mWorld;
	XMMATRIX mView;
	XMMATRIX mProjection;
	XMFLOAT4 vLightDir[2];
	XMFLOAT4 vLightColor[2];
	XMFLOAT4 vOutputColor;
};


//--------------------------------------------------------------------------------------
// 全局变量
//--------------------------------------------------------------------------------------
HINSTANCE               g_hInst = NULL;
HWND                    g_hWnd = NULL;
D3D_DRIVER_TYPE         g_driverType = D3D_DRIVER_TYPE_NULL;
D3D_FEATURE_LEVEL       g_featureLevel = D3D_FEATURE_LEVEL_11_0;
ID3D11Device*           g_pd3dDevice = NULL;
ID3D11DeviceContext*    g_pImmediateContext = NULL;
IDXGISwapChain*         g_pSwapChain = NULL;
ID3D11RenderTargetView* g_pRenderTargetView = NULL;
ID3D11Texture2D*        g_pDepthStencil = NULL;
ID3D11DepthStencilView* g_pDepthStencilView = NULL;
ID3D11VertexShader*     g_pVertexShader = NULL;
ID3D11PixelShader*      g_pPixelShader = NULL;
ID3D11PixelShader*      g_pPixelShaderSolid = NULL;
ID3D11InputLayout*      g_pVertexLayout = NULL;
ID3D11Buffer*           g_pVertexBuffer = NULL;
ID3D11Buffer*           g_pIndexBuffer = NULL;
ID3D11Buffer*           g_pConstantBuffer = NULL;
XMMATRIX                g_World;
XMMATRIX                g_View;
XMMATRIX                g_Projection;


//--------------------------------------------------------------------------------------
// 函数声明
//--------------------------------------------------------------------------------------
HRESULT InitWindow( HINSTANCE hInstance, int nCmdShow );
HRESULT InitDevice();
void CleanupDevice();
LRESULT CALLBACK    WndProc( HWND, UINT, WPARAM, LPARAM );
void Render();


//--------------------------------------------------------------------------------------
// Entry point to the program. Initializes everything and goes into a message processing 
// loop. Idle time is used to render the scene.
//--------------------------------------------------------------------------------------
int WINAPI wWinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPWSTR lpCmdLine, int nCmdShow )
{
    UNREFERENCED_PARAMETER( hPrevInstance );
    UNREFERENCED_PARAMETER( lpCmdLine );

    if( FAILED( InitWindow( hInstance, nCmdShow ) ) )
        return 0;

    if( FAILED( InitDevice() ) )
    {
        CleanupDevice();
        return 0;
    }

    // Main message loop
    MSG msg = {0};
    while( WM_QUIT != msg.message )
    {
        if( PeekMessage( &msg, NULL, 0, 0, PM_REMOVE ) )
        {
            TranslateMessage( &msg );
            DispatchMessage( &msg );
        }
        else
        {
            Render();
        }
    }

    CleanupDevice();

    return ( int )msg.wParam;
}


//--------------------------------------------------------------------------------------
// 注册和创建窗口
//--------------------------------------------------------------------------------------
HRESULT InitWindow( HINSTANCE hInstance, int nCmdShow )
{
    // Register class
    WNDCLASSEX wcex;
    wcex.cbSize = sizeof( WNDCLASSEX );
    wcex.style = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon( hInstance, ( LPCTSTR )IDI_TUTORIAL1 );
    wcex.hCursor = LoadCursor( NULL, IDC_ARROW );
    wcex.hbrBackground = ( HBRUSH )( COLOR_WINDOW + 1 );
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = L"TutorialWindowClass";
    wcex.hIconSm = LoadIcon( wcex.hInstance, ( LPCTSTR )IDI_TUTORIAL1 );
    if( !RegisterClassEx( &wcex ) )
        return E_FAIL;

    // Create window
    g_hInst = hInstance;
    RECT rc = { 0, 0, 640, 480 };
    AdjustWindowRect( &rc, WS_OVERLAPPEDWINDOW, FALSE );
    g_hWnd = CreateWindow( L"TutorialWindowClass", L"Direct3D 11 Tutorial 6", WS_OVERLAPPEDWINDOW,
                           CW_USEDEFAULT, CW_USEDEFAULT, rc.right - rc.left, rc.bottom - rc.top, NULL, NULL, hInstance,
                           NULL );
    if( !g_hWnd )
        return E_FAIL;

    ShowWindow( g_hWnd, nCmdShow );

    return S_OK;
}


//--------------------------------------------------------------------------------------
// Helper for compiling shaders with D3DCompile
//
// With VS 11, we could load up prebuilt .cso files instead...
//--------------------------------------------------------------------------------------
HRESULT CompileShaderFromFile( WCHAR* szFileName, LPCSTR szEntryPoint, LPCSTR szShaderModel, ID3DBlob** ppBlobOut )
{
    HRESULT hr = S_OK;

    DWORD dwShaderFlags = D3DCOMPILE_ENABLE_STRICTNESS;
#if defined( DEBUG ) || defined( _DEBUG )
    // Set the D3DCOMPILE_DEBUG flag to embed debug information in the shaders.
    // Setting this flag improves the shader debugging experience, but still allows 
    // the shaders to be optimized and to run exactly the way they will run in 
    // the release configuration of this program.
    dwShaderFlags |= D3DCOMPILE_DEBUG;
#endif

    ID3DBlob* pErrorBlob;
    hr = D3DCompileFromFile( szFileName, NULL, NULL, szEntryPoint, szShaderModel, 
        dwShaderFlags, 0, ppBlobOut, &pErrorBlob );
    if( FAILED(hr) )
    {
        if( pErrorBlob != NULL )
            OutputDebugStringA( (char*)pErrorBlob->GetBufferPointer() );
        if( pErrorBlob ) pErrorBlob->Release();
        return hr;
    }
    if( pErrorBlob ) pErrorBlob->Release();

    return S_OK;
}


//--------------------------------------------------------------------------------------
// 创建Direct3D设备和交换链
//--------------------------------------------------------------------------------------
HRESULT InitDevice()
{
    HRESULT hr = S_OK;

    RECT rc;
    GetClientRect( g_hWnd, &rc );
    UINT width = rc.right - rc.left;
    UINT height = rc.bottom - rc.top;

    UINT createDeviceFlags = 0;
#ifdef _DEBUG
    createDeviceFlags |= D3D11_CREATE_DEVICE_DEBUG;
#endif

    D3D_DRIVER_TYPE driverTypes[] =
    {
        D3D_DRIVER_TYPE_HARDWARE,
        D3D_DRIVER_TYPE_WARP,
        D3D_DRIVER_TYPE_REFERENCE,
    };
    UINT numDriverTypes = ARRAYSIZE( driverTypes );

    D3D_FEATURE_LEVEL featureLevels[] =
    {
        D3D_FEATURE_LEVEL_11_0,
        D3D_FEATURE_LEVEL_10_1,
        D3D_FEATURE_LEVEL_10_0,
    };
	UINT numFeatureLevels = ARRAYSIZE( featureLevels );

    DXGI_SWAP_CHAIN_DESC sd;
    ZeroMemory( &sd, sizeof( sd ) );
    sd.BufferCount = 1;
    sd.BufferDesc.Width = width;
    sd.BufferDesc.Height = height;
    sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
    sd.BufferDesc.RefreshRate.Numerator = 60;
    sd.BufferDesc.RefreshRate.Denominator = 1;
    sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
    sd.OutputWindow = g_hWnd;
    sd.SampleDesc.Count = 1;
    sd.SampleDesc.Quality = 0;
    sd.Windowed = TRUE;

    for( UINT driverTypeIndex = 0; driverTypeIndex < numDriverTypes; driverTypeIndex++ )
    {
        g_driverType = driverTypes[driverTypeIndex];
        hr = D3D11CreateDeviceAndSwapChain( NULL, g_driverType, NULL, createDeviceFlags, featureLevels, numFeatureLevels,
                                            D3D11_SDK_VERSION, &sd, &g_pSwapChain, &g_pd3dDevice, &g_featureLevel,
                                            &g_pImmediateContext );
        if( SUCCEEDED( hr ) )
            break;
    }
    if( FAILED( hr ) )
        return hr;

    // Create a render target view
    ID3D11Texture2D* pBackBuffer = NULL;
    hr = g_pSwapChain->GetBuffer( 0, __uuidof( ID3D11Texture2D ), ( LPVOID* )&pBackBuffer );
    if( FAILED( hr ) )
        return hr;

    hr = g_pd3dDevice->CreateRenderTargetView( pBackBuffer, NULL, &g_pRenderTargetView );
    pBackBuffer->Release();
    if( FAILED( hr ) )
        return hr;

    // Create depth stencil texture
    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;
    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
    D3D11_DEPTH_STENCIL_VIEW_DESC descDSV;
	ZeroMemory( &descDSV, sizeof(descDSV) );
    descDSV.Format = descDepth.Format;
    descDSV.ViewDimension = D3D11_DSV_DIMENSION_TEXTURE2D;
    descDSV.Texture2D.MipSlice = 0;
    hr = g_pd3dDevice->CreateDepthStencilView( g_pDepthStencil, &descDSV, &g_pDepthStencilView );
    if( FAILED( hr ) )
        return hr;

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

    // Setup the viewport
    D3D11_VIEWPORT vp;
    vp.Width = (FLOAT)width;
    vp.Height = (FLOAT)height;
    vp.MinDepth = 0.0f;
    vp.MaxDepth = 1.0f;
    vp.TopLeftX = 0;
    vp.TopLeftY = 0;
    g_pImmediateContext->RSSetViewports( 1, &vp );

	// Compile the vertex shader
	ID3DBlob* pVSBlob = NULL;
    hr = CompileShaderFromFile( L"Tutorial06.fx", "VS", "vs_4_0", &pVSBlob );
    if( FAILED( hr ) )
    {
        MessageBox( NULL,
                    L"The FX file cannot be compiled.  Please run this executable from the 
                            directory that contains the FX file.", L"Error", MB_OK );
        return hr;
    }

	// Create the vertex shader
	hr = g_pd3dDevice->CreateVertexShader( pVSBlob->GetBufferPointer(), pVSBlob->GetBufferSize(), NULL, &g_pVertexShader );
	if( FAILED( hr ) )
	{	
		pVSBlob->Release();
        return hr;
	}

    // Define the input layout
    D3D11_INPUT_ELEMENT_DESC layout[] =
    {
        { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
        { "NORMAL", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 12, D3D11_INPUT_PER_VERTEX_DATA, 0 },
	};
	UINT numElements = ARRAYSIZE( layout );

    // Create the input layout
	hr = g_pd3dDevice->CreateInputLayout( layout, numElements, pVSBlob->GetBufferPointer(),
                                          pVSBlob->GetBufferSize(), &g_pVertexLayout );
	pVSBlob->Release();
	if( FAILED( hr ) )
        return hr;

    // Set the input layout
    g_pImmediateContext->IASetInputLayout( g_pVertexLayout );

	// Compile the pixel shader
	ID3DBlob* pPSBlob = NULL;
    hr = CompileShaderFromFile( L"Tutorial06.fx", "PS", "ps_4_0", &pPSBlob );
    if( FAILED( hr ) )
    {
        MessageBox( NULL,
                    L"The FX file cannot be compiled.  Please run this executable from the directory 
                            that contains the FX file.", L"Error", MB_OK );
        return hr;
    }

	// Create the pixel shader
	hr = g_pd3dDevice->CreatePixelShader( pPSBlob->GetBufferPointer(), pPSBlob->GetBufferSize(), NULL, &g_pPixelShader );
	pPSBlob->Release();
    if( FAILED( hr ) )
        return hr;

	// Compile the pixel shader
	pPSBlob = NULL;
	hr = CompileShaderFromFile( L"Tutorial06.fx", "PSSolid", "ps_4_0", &pPSBlob );
    if( FAILED( hr ) )
    {
        MessageBox( NULL,
                    L"The FX file cannot be compiled.  Please run this executable from the directory 
                            that contains the FX file.", L"Error", MB_OK );
        return hr;
    }

	// Create the pixel shader
	hr = g_pd3dDevice->CreatePixelShader( pPSBlob->GetBufferPointer(), pPSBlob->GetBufferSize(), NULL, &g_pPixelShaderSolid );
	pPSBlob->Release();
    if( FAILED( hr ) )
        return hr;

    // Create vertex buffer
    SimpleVertex vertices[] =
    {
        { XMFLOAT3( -1.0f, 1.0f, -1.0f ), XMFLOAT3( 0.0f, 1.0f, 0.0f ) },
        { XMFLOAT3( 1.0f, 1.0f, -1.0f ), XMFLOAT3( 0.0f, 1.0f, 0.0f ) },
        { XMFLOAT3( 1.0f, 1.0f, 1.0f ), XMFLOAT3( 0.0f, 1.0f, 0.0f ) },
        { XMFLOAT3( -1.0f, 1.0f, 1.0f ), XMFLOAT3( 0.0f, 1.0f, 0.0f ) },

        { XMFLOAT3( -1.0f, -1.0f, -1.0f ), XMFLOAT3( 0.0f, -1.0f, 0.0f ) },
        { XMFLOAT3( 1.0f, -1.0f, -1.0f ), XMFLOAT3( 0.0f, -1.0f, 0.0f ) },
        { XMFLOAT3( 1.0f, -1.0f, 1.0f ), XMFLOAT3( 0.0f, -1.0f, 0.0f ) },
        { XMFLOAT3( -1.0f, -1.0f, 1.0f ), XMFLOAT3( 0.0f, -1.0f, 0.0f ) },

        { XMFLOAT3( -1.0f, -1.0f, 1.0f ), XMFLOAT3( -1.0f, 0.0f, 0.0f ) },
        { XMFLOAT3( -1.0f, -1.0f, -1.0f ), XMFLOAT3( -1.0f, 0.0f, 0.0f ) },
        { XMFLOAT3( -1.0f, 1.0f, -1.0f ), XMFLOAT3( -1.0f, 0.0f, 0.0f ) },
        { XMFLOAT3( -1.0f, 1.0f, 1.0f ), XMFLOAT3( -1.0f, 0.0f, 0.0f ) },

        { XMFLOAT3( 1.0f, -1.0f, 1.0f ), XMFLOAT3( 1.0f, 0.0f, 0.0f ) },
        { XMFLOAT3( 1.0f, -1.0f, -1.0f ), XMFLOAT3( 1.0f, 0.0f, 0.0f ) },
        { XMFLOAT3( 1.0f, 1.0f, -1.0f ), XMFLOAT3( 1.0f, 0.0f, 0.0f ) },
        { XMFLOAT3( 1.0f, 1.0f, 1.0f ), XMFLOAT3( 1.0f, 0.0f, 0.0f ) },

        { XMFLOAT3( -1.0f, -1.0f, -1.0f ), XMFLOAT3( 0.0f, 0.0f, -1.0f ) },
        { XMFLOAT3( 1.0f, -1.0f, -1.0f ), XMFLOAT3( 0.0f, 0.0f, -1.0f ) },
        { XMFLOAT3( 1.0f, 1.0f, -1.0f ), XMFLOAT3( 0.0f, 0.0f, -1.0f ) },
        { XMFLOAT3( -1.0f, 1.0f, -1.0f ), XMFLOAT3( 0.0f, 0.0f, -1.0f ) },

        { XMFLOAT3( -1.0f, -1.0f, 1.0f ), XMFLOAT3( 0.0f, 0.0f, 1.0f ) },
        { XMFLOAT3( 1.0f, -1.0f, 1.0f ), XMFLOAT3( 0.0f, 0.0f, 1.0f ) },
        { XMFLOAT3( 1.0f, 1.0f, 1.0f ), XMFLOAT3( 0.0f, 0.0f, 1.0f ) },
        { XMFLOAT3( -1.0f, 1.0f, 1.0f ), XMFLOAT3( 0.0f, 0.0f, 1.0f ) },
    };

    D3D11_BUFFER_DESC bd;
	ZeroMemory( &bd, sizeof(bd) );
    bd.Usage = D3D11_USAGE_DEFAULT;
    bd.ByteWidth = sizeof( SimpleVertex ) * 24;
    bd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
	bd.CPUAccessFlags = 0;
    D3D11_SUBRESOURCE_DATA InitData;
	ZeroMemory( &InitData, sizeof(InitData) );
    InitData.pSysMem = vertices;
    hr = g_pd3dDevice->CreateBuffer( &bd, &InitData, &g_pVertexBuffer );
    if( FAILED( hr ) )
        return hr;

    // Set vertex buffer
    UINT stride = sizeof( SimpleVertex );
    UINT offset = 0;
    g_pImmediateContext->IASetVertexBuffers( 0, 1, &g_pVertexBuffer, &stride, &offset );

    // Create index buffer
    WORD indices[] =
    {
        3,1,0,
        2,1,3,

        6,4,5,
        7,4,6,

        11,9,8,
        10,9,11,

        14,12,13,
        15,12,14,

        19,17,16,
        18,17,19,

        22,20,21,
        23,20,22
    };
    bd.Usage = D3D11_USAGE_DEFAULT;
    bd.ByteWidth = sizeof( WORD ) * 36;        // 36 vertices needed for 12 triangles in a triangle list
    bd.BindFlags = D3D11_BIND_INDEX_BUFFER;
	bd.CPUAccessFlags = 0;
    InitData.pSysMem = indices;
    hr = g_pd3dDevice->CreateBuffer( &bd, &InitData, &g_pIndexBuffer );
    if( FAILED( hr ) )
        return hr;

    // Set index buffer
    g_pImmediateContext->IASetIndexBuffer( g_pIndexBuffer, DXGI_FORMAT_R16_UINT, 0 );

    // Set primitive topology
    g_pImmediateContext->IASetPrimitiveTopology( D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST );

	// Create the constant buffer
	bd.Usage = D3D11_USAGE_DEFAULT;
	bd.ByteWidth = sizeof(ConstantBuffer);
	bd.BindFlags = D3D11_BIND_CONSTANT_BUFFER;
	bd.CPUAccessFlags = 0;
    hr = g_pd3dDevice->CreateBuffer( &bd, NULL, &g_pConstantBuffer );
    if( FAILED( hr ) )
        return hr;

    // Initialize the world matrices
	g_World = XMMatrixIdentity();

    // Initialize the view matrix
	XMVECTOR Eye = XMVectorSet( 0.0f, 4.0f, -10.0f, 0.0f );
	XMVECTOR At = XMVectorSet( 0.0f, 1.0f, 0.0f, 0.0f );
	XMVECTOR Up = XMVectorSet( 0.0f, 1.0f, 0.0f, 0.0f );
	g_View = XMMatrixLookAtLH( Eye, At, Up );

    // Initialize the projection matrix
	g_Projection = XMMatrixPerspectiveFovLH( XM_PIDIV4, width / (FLOAT)height, 0.01f, 100.0f );

    return S_OK;
}


//--------------------------------------------------------------------------------------
// Clean up the objects we've created
//--------------------------------------------------------------------------------------
void CleanupDevice()
{
    if( g_pImmediateContext ) g_pImmediateContext->ClearState();

    if( g_pConstantBuffer ) g_pConstantBuffer->Release();
    if( g_pVertexBuffer ) g_pVertexBuffer->Release();
    if( g_pIndexBuffer ) g_pIndexBuffer->Release();
    if( g_pVertexLayout ) g_pVertexLayout->Release();
    if( g_pVertexShader ) g_pVertexShader->Release();
    if( g_pPixelShaderSolid ) g_pPixelShaderSolid->Release();
    if( g_pPixelShader ) g_pPixelShader->Release();
    if( g_pDepthStencil ) g_pDepthStencil->Release();
    if( g_pDepthStencilView ) g_pDepthStencilView->Release();
    if( g_pRenderTargetView ) g_pRenderTargetView->Release();
    if( g_pSwapChain ) g_pSwapChain->Release();
    if( g_pImmediateContext ) g_pImmediateContext->Release();
    if( g_pd3dDevice ) g_pd3dDevice->Release();
}


//--------------------------------------------------------------------------------------
// Called every time the application receives a message
//--------------------------------------------------------------------------------------
LRESULT CALLBACK WndProc( HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam )
{
    PAINTSTRUCT ps;
    HDC hdc;

    switch( message )
    {
        case WM_PAINT:
            hdc = BeginPaint( hWnd, &ps );
            EndPaint( hWnd, &ps );
            break;

        case WM_DESTROY:
            PostQuitMessage( 0 );
            break;

        default:
            return DefWindowProc( hWnd, message, wParam, lParam );
    }

    return 0;
}


//--------------------------------------------------------------------------------------
// Render a frame
//--------------------------------------------------------------------------------------
void Render()
{
    // Update our time
    static float t = 0.0f;
    if( g_driverType == D3D_DRIVER_TYPE_REFERENCE )
    {
        t += ( float )XM_PI * 0.0125f;
    }
    else
    {
        static DWORD dwTimeStart = 0;
        DWORD dwTimeCur = GetTickCount();
        if( dwTimeStart == 0 )
            dwTimeStart = dwTimeCur;
        t = ( dwTimeCur - dwTimeStart ) / 1000.0f;
    }

    // Rotate cube around the origin
	g_World = XMMatrixRotationY( t );

    // 设置光源参数
    XMFLOAT4 vLightDirs[2] =
    {
        XMFLOAT4( -0.577f, 0.577f, -0.577f, 1.0f ),
        XMFLOAT4( 0.0f, 0.0f, -1.0f, 1.0f ),
    };
    XMFLOAT4 vLightColors[2] =
    {
        XMFLOAT4( 0.5f, 0.5f, 0.5f, 1.0f ),
        XMFLOAT4( 0.5f, 0.0f, 0.0f, 1.0f )
    };

    // 使第2个光源绕原点旋转
	XMMATRIX mRotate = XMMatrixRotationY( -2.0f * t );
	XMVECTOR vLightDir = XMLoadFloat4( &vLightDirs[1] );
	vLightDir = XMVector3Transform( vLightDir, mRotate );
	XMStoreFloat4( &vLightDirs[1], vLightDir );

	//
    // Clear the back buffer
    //
    float ClearColor[4] = { 0.0f, 0.125f, 0.3f, 1.0f }; // red, green, blue, alpha
    g_pImmediateContext->ClearRenderTargetView( g_pRenderTargetView, ClearColor );

    //
    // Clear the depth buffer to 1.0 (max depth)
    //
    g_pImmediateContext->ClearDepthStencilView( g_pDepthStencilView, D3D11_CLEAR_DEPTH, 1.0f, 0 );

    //
    // 更新矩阵和光源变量
    //
    ConstantBuffer cb1;
	cb1.mWorld = XMMatrixTranspose( g_World );
	cb1.mView = XMMatrixTranspose( g_View );
	cb1.mProjection = XMMatrixTranspose( g_Projection );
	cb1.vLightDir[0] = vLightDirs[0];
	cb1.vLightDir[1] = vLightDirs[1];
	cb1.vLightColor[0] = vLightColors[0];
	cb1.vLightColor[1] = vLightColors[1];
	cb1.vOutputColor = XMFLOAT4(0, 0, 0, 0);
	g_pImmediateContext->UpdateSubresource( g_pConstantBuffer, 0, NULL, &cb1, 0, 0 );

    //
    // 绘制立方体
    //
	g_pImmediateContext->VSSetShader( g_pVertexShader, NULL, 0 );
	g_pImmediateContext->VSSetConstantBuffers( 0, 1, &g_pConstantBuffer );
	g_pImmediateContext->PSSetShader( g_pPixelShader, NULL, 0 );
	g_pImmediateContext->PSSetConstantBuffers( 0, 1, &g_pConstantBuffer );
	g_pImmediateContext->DrawIndexed( 36, 0, 0 );

    //
    // 绘制两个光源
    //
    for( int m = 0; m < 2; m++ )
    {
		XMMATRIX mLight = XMMatrixTranslationFromVector( 5.0f * XMLoadFloat4( &vLightDirs[m] ) );
		XMMATRIX mLightScale = XMMatrixScaling( 0.2f, 0.2f, 0.2f );
        mLight = mLightScale * mLight;

        // 更新世界矩阵to reflect the current light
		cb1.mWorld = XMMatrixTranspose( mLight );
		cb1.vOutputColor = vLightColors[m];
		g_pImmediateContext->UpdateSubresource( g_pConstantBuffer, 0, NULL, &cb1, 0, 0 );

		g_pImmediateContext->PSSetShader( g_pPixelShaderSolid, NULL, 0 );
		g_pImmediateContext->DrawIndexed( 36, 0, 0 );
    }

    //
    // Present our back buffer to our front buffer
    //
    g_pSwapChain->Present( 0, 0 );
}
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