DirectX3D游戏开发六 场景光照的实现

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    参考：directxtutorial.com DirectX.9.0.3D游戏开发编程基础

    我们之前讲的简单的3D场景都是没有光照的，但是这个和实际的环境是由很大的差距的。在这一节课我们就讲一下怎样为场景添加光照，增强所绘场景的真实感。

    自然界的光照是很复杂的，各种反射、折射等等，游戏中的光照都是尽可能去模拟真实的世界，达到逼真的效果，但是和现实世界还是有差距的！

光的种类

    在Direct3D光照模型中，光源发出的光由三种类型的光组成。

    1、环境光：这种类型的光经由其余物体的表面反射达到物体表面，并照亮整个场景。

    2、漫反射光：这种类型的光沿着特定的方向传播。当它达到某一表面的时候将沿着各个方向均匀反射。由于漫反射的特性，无论从哪个方位观察，表面亮度均相同，所以采用该模型时，无需考虑观察者的位置。这样，漫反射光方程中，只需要考虑光的传播方向以及表面的朝向。表面的朝向就涉及到顶点法线的计算。

    3、镜面光：这种类型的光也沿着特定的方向传播。当它达到某一表面的时候将严格的朝另外一个方向反射。镜面光可用于模拟物体上的高亮点，例如当光线照射到一个抛光的表面所形成的高亮照射。镜面光与其他类型的光相比，计算了要大得多，在Direct3D中镜面光默认是关闭的，开启的方法如下：

g_pd3dDevice->SetRenderState(D3DRS_SPECULARENABLE, TRUE);

    当然还有一个自发光属性，通过对物体材质Emissive属性设置来实现，使之看起来好像可以自己发光

    材质

    材质就是物体的质地。Direct3D中通过材质定义物体表面对各种颜色光的反射比例，在Direct3D中用结构体D3DMATERIAL9来表示材质：

typedef struct _D3DMATERIAL9 {    D3DCOLORVALUE   Diffuse;        /* Diffuse color RGBA */    D3DCOLORVALUE   Ambient;        /* Ambient color RGB */    D3DCOLORVALUE   Specular;       /* Specular 'shininess' */    D3DCOLORVALUE   Emissive;       /* Emissive color RGB */    float           Power;          /* Sharpness if specular highlight */} D3DMATERIAL9;

其中，Diffuse,Ambient,Specular分别表示材质表面对漫反射光、环境光以及镜面光的反射率，Emissive表示物体的自发光，Power表示镜面高光点的锐度。

    Direct3D中使用函数SetMaterial对材质进行设置：

g_pd3dDevice->SetMaterial(&mtrl);

    举个例子来说明材质的设置：   

// Set up a material. The material here just has the diffuse and ambient// colors set to yellow. Note that only one material can be used at a time.D3DMATERIAL9 mtrl;ZeroMemory(&mtrl, sizeof(D3DMATERIAL9));//漫反射光mtrl.Diffuse.r  = 1.0f;mtrl.Diffuse.g  = 1.0f;mtrl.Diffuse.b  = 0.0f;mtrl.Diffuse.a  = 1.0f;//环境光mtrl.Ambient.r = 1.0f;mtrl.Ambient.g = 0.0f;mtrl.Ambient.b = 0.0f;mtrl.Ambient.a = 1.0f;//镜面反射光mtrl.Specular.r = 1.0f;mtrl.Specular.g = 1.0f;mtrl.Specular.b = 1.0f;mtrl.Specular.a = 1.0f;mtrl.Power = 25.0f;//自发光//mtrl.Emissive.r = 0.3f;//mtrl.Emissive.g = 1.0f;//mtrl.Emissive.b = 0.6f;//mtrl.Emissive.a = 1.0f;//设置材质g_pd3dDevice->SetMaterial(&mtrl);//使能镜面光g_pd3dDevice->SetRenderState(D3DRS_SPECULARENABLE, TRUE);

光源

    Direct3D支持三种类型的光源：点光源、方向光和聚光灯，如下所示：

    

    光源用结构D3DLIGHT9来表示：

    

typedef struct _D3DLIGHT9 {    D3DLIGHTTYPE    Type;            /* Type of light source */    D3DCOLORVALUE   Diffuse;         /* Diffuse color of light */    D3DCOLORVALUE   Specular;        /* Specular color of light */    D3DCOLORVALUE   Ambient;         /* Ambient color of light */    D3DVECTOR       Position;         /* Position in world space */    D3DVECTOR       Direction;        /* Direction in world space */    float           Range;            /* Cutoff range */    float           Falloff;          /* Falloff */    float           Attenuation0;     /* Constant attenuation */    float           Attenuation1;     /* Linear attenuation */    float           Attenuation2;     /* Quadratic attenuation */    float           Theta;            /* Inner angle of spotlight cone */    float           Phi;              /* Outer angle of spotlight cone */} D3DLIGHT9;

   点光源

    点光源具有颜色与位置属性，没有方向。光照强度会随着距光源中心的距离变大衰减。在具体应用中，可以利用点光源来模拟电灯或精灵。在Direct3D中设置点光源的方式如下：

    

D3DLIGHT9 light;ZeroMemory(&light, sizeof(D3DLIGHT9));light.Type = D3DLIGHT_POINT;light.Position = D3DXVECTOR3(1.0f,1.0f,1.0f);//漫反射光light.Diffuse.r = 1.0f;light.Diffuse.g = 1.0f;light.Diffuse.b = 1.0f;light.Diffuse.a = 1.0f;light.Range = 10.0f;light.Attenuation0 = 1.0f;g_pd3dDevice->SetLight(0, &light);//对光源进行注册g_pd3dDevice->LightEnable(0, TRUE);//使能光照g_pd3dDevice->SetRenderState(D3DRS_LIGHTING, TRUE);

    聚光灯

   聚光灯具有颜色、方向和位置。聚光灯由内锥与外锥组成，光照强度由内锥到外锥逐渐衰减。在应用中可以模拟探照灯。由于聚光灯计算量比较大，所以尽量少使用。D3D中设置光源方式如下：

    

<span style="font-size:18px;">D3DLIGHT9 light;ZeroMemory(&light, sizeof(D3DLIGHT9));light.Type = D3DLIGHT_SPOT;light.Position = D3DXVECTOR3(0.0f,0.0f,0.0f);light.Direction = D3DXVECTOR3(1.0f, 1.0f, 1.0f);//漫反射光light.Diffuse.r = 1.0f;light.Diffuse.g = 1.0f;light.Diffuse.b = 1.0f;light.Diffuse.a = 1.0f;light.Range = 100.0f;light.Phi = D3DX_PI / 4.0f;light.Theta = D3DX_PI / 8.f;light.Falloff = 1.0f;g_pd3dDevice->SetLight(0, &light);//对光源进行注册g_pd3dDevice->LightEnable(0, TRUE);//使能光照g_pd3dDevice->SetRenderState(D3DRS_LIGHTING, TRUE);</span><span style="font-size:24px;"></span>

方向光

    方向光具有颜色、方向属性，没有位置。方向光不存在范围，所以，计算量在所以光源中最小。在应用中可以模拟太阳光。在D3D中设置光源的方式如下：

    

D3DXVECTOR3 vecDir;D3DLIGHT9 light;ZeroMemory(&light, sizeof(D3DLIGHT9));//类型：light.Type = D3DLIGHT_DIRECTIONAL;//漫反射光light.Diffuse.r = 1.0f; light.Diffuse.g = 1.0f;light.Diffuse.b = 1.0f;light.Diffuse.a = 1.0f;//镜面光light.Specular.r = 1.0f;light.Specular.g = 1.0f;light.Specular.b = 1.0f;light.Specular.a = 1.0f;//光的方向vecDir = D3DXVECTOR3(cosf(timeGetTime() / 350.0f),  //光的方向为原点(0,0,0)指向这个点的方向：两点确定一条直线1.0f,sinf(timeGetTime() / 350.0f));//归一化方向D3DXVec3Normalize((D3DXVECTOR3*)&light.Direction, &vecDir);//light.Range = 1000.0f; //对于方向光无意义g_pd3dDevice->SetLight(0, &light);//对光源进行注册g_pd3dDevice->LightEnable(0, TRUE);//使能光照g_pd3dDevice->SetRenderState(D3DRS_LIGHTING, TRUE);

    例子的运行效果如下：

    

    源代码main.c如下：

    

//-----------------------------------------------------------------------------// File: Lights.cpp//// Desc: Rendering 3D geometry is much more interesting when dynamic lighting//       is added to the scene. To use lighting in D3D, you must create one or//       lights, setup a material, and make sure your geometry contains surface//       normals. Lights may have a position, a color, and be of a certain type//       such as directional (light comes from one direction), point (light//       comes from a specific x,y,z coordinate and radiates in all directions)//       or spotlight. Materials describe the surface of your geometry,//       specifically, how it gets lit (diffuse color, ambient color, etc.).//       Surface normals are part of a vertex, and are needed for the D3D's//       internal lighting calculations.//// Copyright (c) Microsoft Corporation. All rights reserved.//-----------------------------------------------------------------------------#pragma comment(lib, "d3d9.lib")#pragma comment(lib, "d3dx9.lib")#pragma comment(lib,"winmm.lib") #include <Windows.h>#include <mmsystem.h>#include <d3dx9.h>#pragma warning( disable : 4996 ) // disable deprecated warning #include <strsafe.h>#pragma warning( default : 4996 )// define the screen resolutionconst  int  SCREEN_WIDTH = 800;const  int  SCREEN_HEIGHT =800;//-----------------------------------------------------------------------------// 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 type. We added a normal, and omitted the// color (which is provided by the material)struct CUSTOMVERTEX{D3DXVECTOR3 position; // The 3D position for the vertex   D3DXVECTOR3 normal;   // The surface normal for the vertex 法线：因为使用了光照，所以不需要自定义每个顶点的颜色};// Our custom FVF, which describes our custom vertex structure#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZ|D3DFVF_NORMAL)//-----------------------------------------------------------------------------// 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. Since we are now// using more complex geometry, we will create a device with a zbuffer.D3DPRESENT_PARAMETERS d3dpp;ZeroMemory(&d3dpp, sizeof(d3dpp));d3dpp.Windowed = TRUE;d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;d3dpp.BackBufferWidth = SCREEN_WIDTH;d3dpp.BackBufferHeight = SCREEN_HEIGHT;d3dpp.EnableAutoDepthStencil = TRUE;d3dpp.AutoDepthStencilFormat = D3DFMT_D16;//fill D3DCAPS9 struct with the capabilities of the primary display adapterD3DCAPS9 caps;g_pD3D->GetDeviceCaps(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, &caps);//can we use hardware vertex processing?DWORD vp = 0;if (caps.DevCaps&D3DDEVCAPS_HWTRANSFORMANDLIGHT){//yes,support hardware vertex processingvp = D3DCREATE_HARDWARE_VERTEXPROCESSING;}else{//no,vp = D3DCREATE_SOFTWARE_VERTEXPROCESSING;}// Create the D3DDeviceif (FAILED(g_pD3D->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hWnd,vp,&d3dpp, &g_pd3dDevice))){return E_FAIL;}// Turn off cullingg_pd3dDevice->SetRenderState(D3DRS_CULLMODE, D3DCULL_NONE);// Turn on the zbufferg_pd3dDevice->SetRenderState(D3DRS_ZENABLE, TRUE);return S_OK;}//-----------------------------------------------------------------------------// Name: InitGeometry()// Desc: Creates the scene geometry//-----------------------------------------------------------------------------HRESULT InitGeometry(){// Create the vertex buffer.if (FAILED(g_pd3dDevice->CreateVertexBuffer(100 * 2 * sizeof(CUSTOMVERTEX),0, D3DFVF_CUSTOMVERTEX,D3DPOOL_DEFAULT, &g_pVB, NULL))){return E_FAIL;}// Fill the vertex buffer. We are algorithmically generating a cylinder// here, including the normals, which are used for lighting.CUSTOMVERTEX* pVertices;if (FAILED(g_pVB->Lock(0, 0, (void**)&pVertices, 0)))return E_FAIL;for (DWORD i = 0; i < 100; i++){FLOAT theta = (2 * D3DX_PI * i) / (100 - 1);pVertices[2 * i + 0].position = D3DXVECTOR3(sinf(theta), -1.0f, cosf(theta));pVertices[2 * i + 0].normal = D3DXVECTOR3(sinf(theta), 0.0f, cosf(theta));pVertices[2 * i + 1].position = D3DXVECTOR3(sinf(theta), 1.0f, cosf(theta));pVertices[2 * i + 1].normal = D3DXVECTOR3(sinf(theta), 0.0f, cosf(theta));}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(){// Set up world matrixD3DXMATRIXA16 matWorld;D3DXMatrixIdentity(&matWorld);D3DXMatrixRotationX(&matWorld, timeGetTime() / 500.0f);g_pd3dDevice->SetTransform(D3DTS_WORLD, &matWorld);// Set up our view matrix. A view matrix can be defined given an eye point,// a point to lookat, and a direction for which way is up. Here, we set the// eye five units back along the z-axis and up three units, look at the// origin, and define "up" to be in the y-direction.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);// For the projection matrix, we set up a perspective transform (which// transforms geometry from 3D view space to 2D viewport space, with// a perspective divide making objects smaller in the distance). To build// a perpsective transform, we need the field of view (1/4 pi is common),// the aspect ratio, and the near and far clipping planes (which define at// what distances geometry should be no longer be rendered).D3DXMATRIXA16 matProj;D3DXMatrixPerspectiveFovLH(&matProj, D3DX_PI / 4, (FLOAT)SCREEN_WIDTH / (FLOAT)SCREEN_HEIGHT, 1.0f, 100.0f);g_pd3dDevice->SetTransform(D3DTS_PROJECTION, &matProj);}//-----------------------------------------------------------------------------// Name: SetupLights()// Desc: Sets up the lights and materials for the scene.//-----------------------------------------------------------------------------VOID SetupLights(){// Set up a material. The material here just has the diffuse and ambient// colors set to yellow. Note that only one material can be used at a time.D3DMATERIAL9 mtrl;ZeroMemory(&mtrl, sizeof(D3DMATERIAL9));//漫反射光mtrl.Diffuse.r  = 1.0f;mtrl.Diffuse.g  = 1.0f;mtrl.Diffuse.b  = 0.0f;mtrl.Diffuse.a  = 1.0f;//环境光mtrl.Ambient.r = 1.0f;mtrl.Ambient.g = 0.0f;mtrl.Ambient.b = 0.0f;mtrl.Ambient.a = 1.0f;//镜面反射光mtrl.Specular.r = 1.0f;mtrl.Specular.g = 1.0f;mtrl.Specular.b = 1.0f;mtrl.Specular.a = 1.0f;mtrl.Power = 25.0f;//自发光//mtrl.Emissive.r = 0.3f;//mtrl.Emissive.g = 1.0f;//mtrl.Emissive.b = 0.6f;//mtrl.Emissive.a = 1.0f;//设置材质g_pd3dDevice->SetMaterial(&mtrl);//使能镜面光g_pd3dDevice->SetRenderState(D3DRS_SPECULARENABLE, TRUE);// Set up a white, directional light, with an oscillating direction.// Note that many lights may be active at a time (but each one slows down// the rendering of our scene). However, here we are just using one. Also,// we need to set the D3DRS_LIGHTING renderstate to enable lightingD3DXVECTOR3 vecDir;D3DLIGHT9 light;ZeroMemory(&light, sizeof(D3DLIGHT9));//类型：light.Type = D3DLIGHT_DIRECTIONAL;//漫反射光light.Diffuse.r = 1.0f; light.Diffuse.g = 1.0f;light.Diffuse.b = 1.0f;light.Diffuse.a = 1.0f;//镜面光light.Specular.r = 1.0f;light.Specular.g = 1.0f;light.Specular.b = 1.0f;light.Specular.a = 1.0f;/*D3DLIGHT9 light;ZeroMemory(&light, sizeof(D3DLIGHT9));light.Type = D3DLIGHT_SPOT;light.Position = D3DXVECTOR3(0.0f,0.0f,0.0f);light.Direction = D3DXVECTOR3(1.0f, 1.0f, 1.0f);//漫反射光light.Diffuse.r = 1.0f;light.Diffuse.g = 1.0f;light.Diffuse.b = 1.0f;light.Diffuse.a = 1.0f;light.Range = 100.0f;light.Phi = D3DX_PI / 4.0f;light.Theta = D3DX_PI / 8.f;light.Falloff = 1.0f;g_pd3dDevice->SetLight(0, &light);//对光源进行注册g_pd3dDevice->LightEnable(0, TRUE);//使能光照g_pd3dDevice->SetRenderState(D3DRS_LIGHTING, TRUE);*///光的方向vecDir = D3DXVECTOR3(cosf(timeGetTime() / 350.0f),  //光的方向为原点(0,0,0)指向这个点的方向：两点确定一条直线1.0f,sinf(timeGetTime() / 350.0f));//归一化方向D3DXVec3Normalize((D3DXVECTOR3*)&light.Direction, &vecDir);light.Range = 1000.0f;g_pd3dDevice->SetLight(0, &light);//对光源进行注册g_pd3dDevice->LightEnable(0, TRUE);//使能光照g_pd3dDevice->SetRenderState(D3DRS_LIGHTING, TRUE);// 打开环境光g_pd3dDevice->SetRenderState(D3DRS_AMBIENT, 0x00202020);}//-----------------------------------------------------------------------------// Name: Render()// Desc: Draws the scene//-----------------------------------------------------------------------------VOID Render(){// Clear the backbuffer and the zbufferg_pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER,D3DCOLOR_XRGB(0, 0, 255), 1.0f, 0);// Begin the sceneif (SUCCEEDED(g_pd3dDevice->BeginScene())){// Setup the lights and materialsSetupLights();// Setup the world, view, and projection matricesSetupMatrices();// Render the vertex buffer contentsg_pd3dDevice->SetStreamSource(0, g_pVB, 0, sizeof(CUSTOMVERTEX));g_pd3dDevice->SetFVF(D3DFVF_CUSTOMVERTEX);g_pd3dDevice->DrawPrimitive(D3DPT_TRIANGLESTRIP, 0, 2 * 100 - 2);// End the sceneg_pd3dDevice->EndScene();}// Present the backbuffer contents to the displayg_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 wWinMain(HINSTANCE hInst, HINSTANCE, LPWSTR, INT){UNREFERENCED_PARAMETER(hInst);// Register the window classWNDCLASSEX wc ={sizeof(WNDCLASSEX), CS_CLASSDC, MsgProc, 0L, 0L,GetModuleHandle(NULL), NULL, LoadCursor(NULL,IDC_CROSS), NULL, NULL,L"D3D Tutorial", NULL};RegisterClassEx(&wc);// Create the application's windowHWND hWnd = CreateWindow(L"D3D Tutorial", L"D3D Tutorial 04: Lights",WS_DLGFRAME|WS_SYSMENU, 100, 100, SCREEN_WIDTH, SCREEN_HEIGHT,NULL, NULL, wc.hInstance, NULL);// Initialize Direct3Dif (SUCCEEDED(InitD3D(hWnd))){// Create the geometryif (SUCCEEDED(InitGeometry())){// Show the windowShowWindow(hWnd, SW_SHOWDEFAULT);UpdateWindow(hWnd);// Enter the message loopMSG msg;ZeroMemory(&msg, sizeof(msg));while (msg.message != WM_QUIT){if (PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE)){TranslateMessage(&msg);DispatchMessage(&msg);}elseRender();}}}UnregisterClass(L"D3D Tutorial", wc.hInstance);return 0;}