Tutorial 2: Rendering a Triangle

DX11                                      DX9命名变化：

不需要D3D object         　　需要用IDirect3D9 object创建Device

ID3D11Device                   IDirect3DDevice9

ID3D11VertexShader        IDirect3DVertexShader9

ID3D11PixelShader           IDirect3DPixelShader9

D3D_PRIMITIVE_TOPOLOGY 图元拓扑（绘制方式）

Vertex layout定义：

Vertex layout defines how these attributes lie in memory: what data type each attribute uses, what size each attribute has, and the

order of the attributes in memory. Because the attributes usually have different types, similar to the fields in a C structure,

a vertex is usually represented by a structure. The size of the vertex is conveniently obtained from the size of the structure.

input layout 定义：

In Direct3D 11, an input layout is a Direct3D object that describes the structure of vertices in a way that can be understood by the

GPU. Each vertex attribute can be described with the D3D11_INPUT_ELEMENT_DESC structure.

D3D11_INPUT_ELEMENT_DESC 定义：（输入结构元素描述）

typedef struct D3D11_INPUT_ELEMENT_DESC {

  LPCSTR                     　　SemanticName;//HLSL语义名

  UINT                       　　  SemanticIndex;//语义名索引，如第一个color元素为0，第二个color元素为1

  DXGI_FORMAT                Format;//数据格式

  UINT                       　　 InputSlot;//输入槽编号

  UINT                      　　  AlignedByteOffset;//元素间的偏移量，如果是相连排列的，则为0

  D3D11_INPUT_CLASSIFICATION 　　InputSlotClass;//D3D11_INPUT_PER_VERTEX_DATA或D3D11_INPUT_PER_INSTANCE_DATA，前者表示顶点数据，后者表示instance数据

  UINT                       　　InstanceDataStepRate;//顶点数据时，设为0

} D3D11_INPUT_ELEMENT_DESC;

Input-Assembler Stage:[管线的输入装配阶段]

(1)to read primitive data (points, lines and/or triangles) from user-filled buffers and assemble the data into primitives that will be used by the other pipeline stages.

(2)to attach system-generated values to help make shaders more efficient.

输入槽：

数据通过输入槽进入IA阶段，IA阶段有n个输入槽，在使用多个数据缓存（use multiple buffers）时，每个定点缓存必须被分配到不同的输入槽中。

创建定点缓存:

在D3D11中创建顶点缓存，需要填充2个结构：D3D11_BUFFER_DESC和D3D11_SUBRESOURCE_DATA，然后调用ID3D11Device::CreateBuffer()

设置顶点缓存：

ID3D11DeviceContext::IASetVertexBuffers

#include <windows.h>
#include <d3d11.h>
#include <d3dx11.h>
#include <d3dcompiler.h>
#include <xnamath.h>

#pragma comment(lib, "d3d11.lib")
#pragma comment(lib, "d3dx11.lib")
#pragma comment(lib, "dxguid.lib")
#pragma comment(lib, "winmm.lib")

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


//--------------------------------------------------------------------------------------
// Global Variables
//--------------------------------------------------------------------------------------
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;

ID3D11VertexShader*     g_pVertexShader = NULL;///顶点着色器
ID3D11PixelShader*      g_pPixelShader = NULL;///像素着色器
ID3D11InputLayout*      g_pVertexLayout = NULL;///输入结构
ID3D11Buffer*           g_pVertexBuffer = NULL;///定点缓存


//--------------------------------------------------------------------------------------
// Forward declarations
//--------------------------------------------------------------------------------------
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;
}


//--------------------------------------------------------------------------------------
// Register class and create window
//--------------------------------------------------------------------------------------
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, IDI_APPLICATION );
    wcex.hCursor = LoadCursor( NULL, IDC_ARROW );
    wcex.hbrBackground = ( HBRUSH )( COLOR_WINDOW + 1 );
    wcex.lpszMenuName = NULL;
    wcex.lpszClassName = L"TutorialWindowClass";
    wcex.hIconSm = LoadIcon( wcex.hInstance, IDI_APPLICATION );
    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 2: Rendering a Triangle",
                           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 D3DX11
//--------------------------------------------------------------------------------------
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 = D3DX11CompileFromFile( szFileName, NULL, NULL, szEntryPoint, szShaderModel, 
        dwShaderFlags, 0, NULL, ppBlobOut, &pErrorBlob, NULL );
    if( FAILED(hr) )
    {
        if( pErrorBlob != NULL )
            OutputDebugStringA( (char*)pErrorBlob->GetBufferPointer() );
        if( pErrorBlob ) pErrorBlob->Release();
        return hr;
    }
    if( pErrorBlob ) pErrorBlob->Release();

    return S_OK;
}


//--------------------------------------------------------------------------------------
// Create Direct3D device and swap chain
//--------------------------------------------------------------------------------------
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;

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

    // 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 );

	//******************************************* 编译和创建顶点着色器
    // Compile the vertex shader
    ID3DBlob* pVSBlob = NULL;
    hr = CompileShaderFromFile( L"Tutorial02.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;
	}
	//******************************************* end 编译和创建顶点着色器

	//******************************************* Input Layout
    // Define the input layout 定义输入结构
    D3D11_INPUT_ELEMENT_DESC layout[] =
    {
        { "POSITION", 0, DXGI_FORMAT_R32G32B32_FLOAT, 0, 0, D3D11_INPUT_PER_VERTEX_DATA, 0 },
    };
	UINT numElements = ARRAYSIZE( layout );

    //使用ID3D11Device::CreateInputLayout()创建一个输入结构
	hr = g_pd3dDevice->CreateInputLayout( layout, numElements, pVSBlob->GetBufferPointer(),
                                          pVSBlob->GetBufferSize(), &g_pVertexLayout );
	pVSBlob->Release();
	if( FAILED( hr ) )
        return hr;

    //使用ID3D11DeviceContext::IASetInputLayout()设置一个输入结构为active
    g_pImmediateContext->IASetInputLayout( g_pVertexLayout );

	//******************************************* end Input Layout

	//******************************************* 编译和创建像素着色器
	// Compile the pixel shader
	ID3DBlob* pPSBlob = NULL;
    hr = CompileShaderFromFile( L"Tutorial02.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;
	//******************************************* end 编译和创建像素着色器

	//******************************************* 创建定点缓存 设置顶点缓存
    // Create vertex buffer
    SimpleVertex vertices[] =///顶点数据
    {
        XMFLOAT3( 0.0f, 0.5f, 0.5f ),
        XMFLOAT3( 0.5f, -0.5f, 0.5f ),
        XMFLOAT3( -0.5f, -0.5f, 0.5f ),
    };
    D3D11_BUFFER_DESC bd;
	ZeroMemory( &bd, sizeof(bd) );
    bd.Usage = D3D11_USAGE_DEFAULT;
    bd.ByteWidth = sizeof( SimpleVertex ) * 3;
    bd.BindFlags = D3D11_BIND_VERTEX_BUFFER;
	bd.CPUAccessFlags = 0;
    D3D11_SUBRESOURCE_DATA InitData;
	ZeroMemory( &InitData, sizeof(InitData) );
    InitData.pSysMem = vertices;///创建VB时，实际需要复制到缓存的数据
    hr = g_pd3dDevice->CreateBuffer( &bd, &InitData, &g_pVertexBuffer );
    if( FAILED( hr ) )
        return hr;

    // Set vertex buffer 将定点缓存绑定到设备
    UINT stride = sizeof( SimpleVertex );
    UINT offset = 0;
    g_pImmediateContext->IASetVertexBuffers( 0, 1, &g_pVertexBuffer, &stride, &offset );
	//******************************************* end 创建定点缓存 设置顶点缓存

    // Set primitive topology 设置图元拓扑
    g_pImmediateContext->IASetPrimitiveTopology( D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST );

    return S_OK;
}


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

    if( g_pVertexBuffer ) g_pVertexBuffer->Release();
    if( g_pVertexLayout ) g_pVertexLayout->Release();
    if( g_pVertexShader ) g_pVertexShader->Release();
    if( g_pPixelShader ) g_pPixelShader->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()
{
    // 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 );

    // Render a triangle
	g_pImmediateContext->VSSetShader( g_pVertexShader, NULL, 0 );
	g_pImmediateContext->PSSetShader( g_pPixelShader, NULL, 0 );
	// commands the GPU to render using the current vertex buffer, vertex layout, and primitive topology. 
    g_pImmediateContext->Draw( 3, 0 );//第一个参数表示要发送给GPU的顶点数目，第二个参数表示发送的起始顶点的index

    // Present the information rendered to the back buffer to the front buffer (the screen)
    g_pSwapChain->Present( 0, 0 );
}

//File: Tutorial02.fx

//Vertex Shader

float4 VS( float4 Pos : POSITION ) : SV_POSITION //SV_POSITION tells the data associated with the semantics defines the clip-space position.

{  

　　return Pos;

}

//Pixel Shader

float4 PS( float4 Pos : SV_POSITION ) : SV_Target //semantics SV_TARGET means outputting to the render target format.

{    

　　return float4( 1.0f, 1.0f, 0.0f, 1.0f );    // Yellow, with Alpha = 1

}