DirectX 9.0 C++ 课程 关于Perspective projection,Matrices,摄像头，旋转

DirectX 9.0 C++ 教程 关于Perspective projection,Matrices,摄像头，旋转

效果图：

对上面这张gif图片是如何制作感兴趣？看截取视频，然后制成gif 教程

1.坐标系

  默认情况下，Direct3D使用的是左手坐标系。这意味着虚拟3D网格上的每个正坐标远离观察者的方向。例如，Z轴的正坐标是冲向屏幕里面的，Y轴的正坐标是向上的，而X轴的正坐标是向右的。这里提下OpenGL使用的是右手坐标系，Z轴的正坐标是冲向屏幕外面的。X轴和Y轴是一样的。

2.先介绍下Projection,即投射

投射主要分下面的两种。
1.透视投射 （perspective projection） ，远处的物体会小些，像我们现实中眼睛看到的样子2.平行投射（parallel projection） 不管物体离摄像机多远，物体大小不变，一般用在2D编程

在我们程序中不仅要规定摄像头的位置(就是上图中眼睛的位置)，还要规定摄像头看的范围，如果物体在范围之外，会被切割掉。中文叫视锥体，就是下图中阴影部分。看图我们发现要定义3个东西，fovy(用角度)，near(到摄像头的最近距离)，far(到摄像头最远的距离)，还有个纵横比(aspect radio)。

//-----------------------------------------// File: Matrices.cpp//// Desc: Now that we know how to create a device and render some 2D vertices,//       this tutorial goes the next step and renders 3D geometry. To deal with//       3D geometry we need to introduce the use of 4x4 Matrices to transform//       the geometry with translations, rotations, scaling, and setting up our//       camera.////       Geometry is defined in model space. We can move it (translation),//       rotate it (rotation), or stretch it (scaling) using a world transform.//       The geometry is then said to be in world space. Next, we need to//       position the camera, or eye point, somewhere to look at the geometry.//       Another transform, via the view matrix, is used, to position and//       rotate our view. With the geometry then in view space, our last//       transform is the projection transform, which "projects" the 3D scene//       into our 2D viewport.////       Note that in this tutorial, we are introducing the use of D3DX, which//       is a set of helper utilities for D3D. In this case, we are using some//       of D3DX's useful matrix initialization functions. To use D3DX, simply//       include <d3dx9.h> and link with d3dx9.lib.//// Copyright (c) Microsoft Corporation. All rights reserved.//-----------------------------------------#include <Windows.h>#include <mmsystem.h>#include <d3dx9.h>#include <strsafe.h>//-----------------------------------------// Global variables//-----------------------------------------LPDIRECT3D9             g_pD3D       = NULL; // Used to create the D3DDeviceLPDIRECT3DDEVICE9       g_pd3dDevice = NULL; // Our rendering deviceLPDIRECT3DVERTEXBUFFER9 g_pVB        = NULL; // Buffer to hold Vertices// A structure for our custom vertex typestruct CUSTOMVERTEX{    FLOAT x, y, z; // The transformed position for the vertex    DWORD color;        // The vertex color};// Our custom FVF, which describes our custom vertex structure#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ|D3DFVF_DIFFUSE)//#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW)//-----------------------------------------// Name: InitD3D()// Desc: Initializes Direct3D//-----------------------------------------HRESULT InitD3D( HWND hWnd ){    // Create the D3D object.    if( NULL == ( g_pD3D = Direct3DCreate9( D3D_SDK_VERSION ) ) )        return E_FAIL;    // Set up the structure used to create the D3DDevice    D3DPRESENT_PARAMETERS d3dpp;    ZeroMemory( &d3dpp, sizeof(d3dpp) );    d3dpp.Windowed = TRUE;    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;    d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;    // Create the D3DDevice    if( FAILED( g_pD3D->CreateDevice( D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd,                                      D3DCREATE_SOFTWARE_VERTEXPROCESSING,                                      &d3dpp, &g_pd3dDevice ) ) )    {        return E_FAIL;    }    // Turn off culling, so we see the front and back of the triangle    g_pd3dDevice->SetRenderState( D3DRS_CULLMODE, D3DCULL_NONE );    // Turn off D3D lighting, since we are providing our own vertex colors    g_pd3dDevice->SetRenderState( D3DRS_LIGHTING, FALSE );    return S_OK;}//-----------------------------------------// Name: InitVB()// Desc: Creates a vertex buffer and fills it with our Vertices. The vertex//       buffer is basically just a chuck of memory that holds Vertices. After//       creating it, we must Lock()/Unlock() it to fill it. For indices, D3D//       also uses index buffers. The special thing about vertex and index//       buffers is that they can be created in device memory, allowing some//       cards to process them in hardware, resulting in a dramatic//       performance gain.//-----------------------------------------HRESULT InitVB(){    // 因为是矩形，所以要定义4个点    CUSTOMVERTEX Vertices[] =    {        { -1.0f, -1.0f, 0.0f, D3DCOLOR_XRGB(0,255,255), }, // x, y, z, rhw, color        { -1.0f, 1.0f, 0.0f, D3DCOLOR_XRGB(255,0,0), },        { 1.0f, -1.0f, 0.0f, D3DCOLOR_XRGB(0,255,0), },{ 1.0f, 1.0f, 0.0f, D3DCOLOR_XRGB(0,0,255), },    };    // Create the vertex buffer. Here we are allocating enough memory    // (from the default pool) to hold all our 3 custom Vertices. We also    // specify the FVF, so the vertex buffer knows what data it contains.    if( FAILED( g_pd3dDevice->CreateVertexBuffer( sizeof(Vertices),                                                  0, D3DFVF_CUSTOMVERTEX,                                                  D3DPOOL_DEFAULT, &g_pVB, NULL ) ) )    {        return E_FAIL;    }    // Now we fill the vertex buffer. To do this, we need to Lock() the VB to    // gain access to the Vertices. This mechanism is required becuase vertex    // buffers may be in device memory.    VOID* pVertices;    if( FAILED( g_pVB->Lock( 0, sizeof(Vertices), (void**)&pVertices, 0 ) ) )        return E_FAIL;    memcpy( pVertices, Vertices, sizeof(Vertices) );    g_pVB->Unlock();    return S_OK;}//-----------------------------------------// Name: Cleanup()// Desc: Releases all previously initialized objects//-----------------------------------------VOID Cleanup(){    if( g_pVB != NULL )                g_pVB->Release();    if( g_pd3dDevice != NULL )         g_pd3dDevice->Release();    if( g_pD3D != NULL )               g_pD3D->Release();}//-----------------------------------------// Name: SetupMatrices()// Desc: Sets up the world, view, and projection transform Matrices.//-----------------------------------------VOID SetupMatrices(){    // For our world matrix, we will just rotate the object about the y-axis.    D3DXMATRIXA16 matWorld;    // 根据时间，改变角度旋转    UINT  iTime  = timeGetTime() % 1000;    FLOAT fAngle = iTime * (2.0f * D3DX_PI) / 1000.0f;    D3DXMatrixRotationY( &matWorld, fAngle);    g_pd3dDevice->SetTransform( D3DTS_WORLD, &matWorld );    // 定义摄像头的位置    D3DXVECTOR3 vEyePt(0.0f, 3.0f,-5.0f );    D3DXVECTOR3 vLookatPt( 0.0f, 0.0f, 0.0f );    D3DXVECTOR3 vUpVec( 0.0f, 1.0f, 0.0f );    D3DXMATRIXA16 matView;    D3DXMatrixLookAtLH( &matView, &vEyePt, &vLookatPt, &vUpVec );    g_pd3dDevice->SetTransform( D3DTS_VIEW, &matView );    // 定义视锥体的大小    D3DXMATRIXA16 matProj;    D3DXMatrixPerspectiveFovLH( &matProj, D3DX_PI/4, 640/480, 1.0f, 100.0f );    g_pd3dDevice->SetTransform( D3DTS_PROJECTION, &matProj );}//-----------------------------------------// Name: Render()// Desc: Draws the scene//-----------------------------------------VOID Render(){    // 黑色    g_pd3dDevice->Clear( 0, NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0,0,0), 1.0f, 0 );    // Begin the scene    if( SUCCEEDED( g_pd3dDevice->BeginScene() ) )    {        // Setup the world, view, and projection Matrices        SetupMatrices();        // Render the vertex buffer contents        g_pd3dDevice->SetStreamSource( 0, g_pVB, 0, sizeof(CUSTOMVERTEX) );        g_pd3dDevice->SetFVF( D3DFVF_CUSTOMVERTEX );        g_pd3dDevice->DrawPrimitive( D3DPT_TRIANGLESTRIP, 0, 2 );//因为是矩形，所以是由两个三角形组成        // End the scene        g_pd3dDevice->EndScene();    }    // Present the backbuffer contents to the display    g_pd3dDevice->Present( NULL, NULL, NULL, NULL );}//-----------------------------------------// Name: MsgProc()// Desc: The window's message handler//-----------------------------------------LRESULT WINAPI MsgProc( HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam ){    switch( msg )    {        case WM_DESTROY:            Cleanup();            PostQuitMessage( 0 );            return 0;    }    return DefWindowProc( hWnd, msg, wParam, lParam );}//-----------------------------------------// Name: WinMain()// Desc: The application's entry point//-----------------------------------------INT WINAPI WinMain( HINSTANCE hInst, HINSTANCE, LPSTR, INT ){    // Register the window class    WNDCLASSEX wc = { sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L, 0L,                      GetModuleHandle(NULL), NULL, NULL, NULL, NULL,                      "D3D Tutorial", NULL };    RegisterClassEx( &wc );    // Create the application's window    HWND hWnd = CreateWindow( "D3D Tutorial", "D3D Tutorial 03: Matrices",                              WS_OVERLAPPEDWINDOW, 100, 100, 640, 480,                              GetDesktopWindow(), NULL, wc.hInstance, NULL );    // Initialize Direct3D    if( SUCCEEDED( InitD3D( hWnd ) ) )    {        // Create the vertex buffer        if( SUCCEEDED( InitVB() ) )        {            // Show the window            ShowWindow( hWnd, SW_SHOWDEFAULT );            UpdateWindow( hWnd );            // Enter the message loop            MSG msg;            ZeroMemory( &msg, sizeof(msg) );            while( msg.message!=WM_QUIT )            {                if( PeekMessage( &msg, NULL, 0U, 0U, PM_REMOVE ) )                {                    TranslateMessage( &msg );                    DispatchMessage( &msg );                }                else                    Render();            }        }    }    UnregisterClass( "D3D Tutorial", wc.hInstance );    return 0;}

文章源地址：http://www.waitingfy.com/?p=216

项目下载：http://download.csdn.net/detail/fox64194167/4628069(CSDN下载，免积分)

                Matrices  （本地下载）

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