OpenGL入门笔记（六）
其实纹理滤波是什么概念我也还不了解，图形学就是这样，理论和实践都不可偏废，可究竟从何处入手也是个两难的问题，有人说“图形血到最后就是数学”，对我这样的新手来说，快速有个概念也许不失为一个笨办法吧。
Nehe在第6课里已经用了线性滤波了，并且还推荐我们把gl_nearest（不光滑）滤波方式和线性滤波结合起来使用，在近处时用线性滤波，在远处时用gl_nearest（不光滑）滤波，因为线性滤波对运行机器的要求高些。
Demo7
#include <windows.h> // Header File For Windows#include <stdio.h> // Header File For Standard Input/Output#include <gl\gl.h> // Header File For The OpenGL32 Library#include <gl\glu.h> // Header File For The GLu32 Library#include <gl\glaux.h> // Header File For The Glaux LibraryHDC hDC=NULL; // Private GDI Device ContextHGLRC hRC=NULL; // Permanent Rendering ContextHWND hWnd=NULL; // Holds Our Window HandleHINSTANCE hInstance; // Holds The Instance Of The Applicationbool keys[256]; // Array Used For The Keyboard Routinebool active=TRUE; // Window Active Flag Set To TRUE By Defaultbool fullscreen=TRUE; // Fullscreen Flag Set To Fullscreen Mode By Defaultbool light; // Lighting ON/OFF ( NEW )bool lp; // L Pressed? ( NEW )bool fp; // F Pressed? ( NEW )GLfloat xrot; // X RotationGLfloat yrot; // Y RotationGLfloat xspeed; // X Rotation SpeedGLfloat yspeed; // Y Rotation SpeedGLfloat z=-5.0f; // Depth Into The ScreenGLfloat LightAmbient[]= 
{ 0.5f, 0.5f, 0.5f, 1.0f };GLfloat LightDiffuse[]= { 1.0f, 1.0f, 1.0f, 1.0f };GLfloat LightPosition[]= { 0.0f, 0.0f, 2.0f, 1.0f };GLuint filter; // Which Filter To UseGLuint texture[3]; // Storage For 3 TexturesLRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM); // Declaration For WndProcAUX_RGBImageRec *LoadBMP(char *Filename) // Loads A Bitmap Image{
FILE *File=NULL; // File Handle if (!Filename) // Make Sure A Filename Was Given
{ return NULL; // If Not Return NULL
} File=fopen(Filename,"r"); // Check To See If The File Exists if (File) // Does The File Exist? { fclose(File); // Close The Handle return auxDIBImageLoad(Filename); // Load The Bitmap And Return A Pointer } return NULL; // If Load Failed Return NULL
}int LoadGLTextures() // Load Bitmaps And Convert To Textures{ int Status=FALSE; // Status Indicator AUX_RGBImageRec *TextureImage[1]; // Create Storage Space For The Texture memset(TextureImage,0,sizeof(void *)*1); // Set The Pointer To NULL // Load The Bitmap, Check For Errors, If Bitmap's Not Found Quit if (TextureImage[0]=LoadBMP("Data/Crate.bmp")) { Status=TRUE; // Set The Status To TRUE glGenTextures(3, &texture[0]); // Create Three Textures // Create Nearest Filtered Texture glBindTexture(GL_TEXTURE_2D, texture[0]); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST); glTexImage2D(GL_TEXTURE_2D, 0, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data); // Create Linear Filtered Texture glBindTexture(GL_TEXTURE_2D, texture[1]); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data); // Create MipMapped Texture glBindTexture(GL_TEXTURE_2D, texture[2]); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_NEAREST); gluBuild2DMipmaps(GL_TEXTURE_2D, 3, TextureImage[0]->sizeX, TextureImage[0]->sizeY, GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data); } if (TextureImage[0]) // If Texture Exists { if (TextureImage[0]->data) // If Texture Image Exists { free(TextureImage[0]->data); // Free The Texture Image Memory } free(TextureImage[0]); // Free The Image Structure } return Status; // Return The Status}GLvoid ReSizeGLScene(GLsizei width, GLsizei height) // Resize And Initialize The GL Window{ if (height==0) // Prevent A Divide By Zero By { height=1; // Making Height Equal One } glViewport(0,0,width,height); // Reset The Current Viewport glMatrixMode(GL_PROJECTION); // Select The Projection Matrix glLoadIdentity(); // Reset The Projection Matrix // Calculate The Aspect Ratio Of The Window gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f); glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix glLoadIdentity(); // Reset The Modelview Matrix}int InitGL(GLvoid) // All Setup For OpenGL Goes Here{ if (!LoadGLTextures()) // Jump To Texture Loading Routine { return FALSE; // If Texture Didn't Load Return FALSE } glEnable(GL_TEXTURE_2D); // Enable Texture Mapping glShadeModel(GL_SMOOTH); // Enable Smooth Shading glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Black Background glClearDepth(1.0f); // Depth Buffer Setup glEnable(GL_DEPTH_TEST); // Enables Depth Testing glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations glLightfv(GL_LIGHT1, GL_AMBIENT, LightAmbient); // Setup The Ambient Light glLightfv(GL_LIGHT1, GL_DIFFUSE, LightDiffuse); // Setup The Diffuse Light glLightfv(GL_LIGHT1, GL_POSITION,LightPosition); // Position The Light glEnable(GL_LIGHT1); // Enable Light One return TRUE; // Initialization Went OK}int DrawGLScene(GLvoid) // Here's Where We Do All The Drawing{ glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer glLoadIdentity(); // Reset The View glTranslatef(0.0f,0.0f,z); glRotatef(xrot,1.0f,0.0f,0.0f); glRotatef(yrot,0.0f,1.0f,0.0f); glBindTexture(GL_TEXTURE_2D, texture[filter]); glBegin(GL_QUADS); // Front Face glNormal3f( 0.0f, 0.0f, 1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f); // Back Face glNormal3f( 0.0f, 0.0f,-1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f); // Top Face glNormal3f( 0.0f, 1.0f, 0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, 1.0f, 1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, 1.0f, 1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f); // Bottom Face glNormal3f( 0.0f,-1.0f, 0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, -1.0f, -1.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, -1.0f, -1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); // Right face glNormal3f( 1.0f, 0.0f, 0.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, -1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, -1.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 1.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 1.0f); // Left Face glNormal3f(-1.0f, 0.0f, 0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, -1.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 1.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, -1.0f); glEnd(); xrot+=xspeed; yrot+=yspeed; return TRUE; // Keep Going}GLvoid KillGLWindow(GLvoid) // Properly Kill The Window{ if (fullscreen) // Are We In Fullscreen Mode? { ChangeDisplaySettings(NULL,0); // If So Switch Back To The Desktop ShowCursor(TRUE); // Show Mouse Pointer } if (hRC) // Do We Have A Rendering Context? { if (!wglMakeCurrent(NULL,NULL)) // Are We Able To Release The DC And RC Contexts? { MessageBox(NULL,"Release Of DC And RC Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION); } if (!wglDeleteContext(hRC)) // Are We Able To Delete The RC? { MessageBox(NULL,"Release Rendering Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION); } hRC=NULL; // Set RC To NULL } if (hDC && !ReleaseDC(hWnd,hDC)) // Are We Able To Release The DC { MessageBox(NULL,"Release Device Context Failed.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION); hDC=NULL; // Set DC To NULL } if (hWnd && !DestroyWindow(hWnd)) // Are We Able To Destroy The Window? { MessageBox(NULL,"Could Not Release hWnd.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION); hWnd=NULL; // Set hWnd To NULL } if (!UnregisterClass("OpenGL",hInstance)) // Are We Able To Unregister Class { MessageBox(NULL,"Could Not Unregister Class.","SHUTDOWN ERROR",MB_OK | MB_ICONINFORMATION); hInstance=NULL; // Set hInstance To NULL }}/**//* This Code Creates Our OpenGL Window. Parameters Are: * * title - Title To Appear At The Top Of The Window * * width - Width Of The GL Window Or Fullscreen Mode * * height - Height Of The GL Window Or Fullscreen Mode * * bits - Number Of Bits To Use For Color (8/16/24/32) * * fullscreenflag - Use Fullscreen Mode (TRUE) Or Windowed Mode (FALSE) */ BOOL CreateGLWindow(char* title, int width, int height, int bits, bool fullscreenflag){ GLuint PixelFormat; // Holds The Results After Searching For A Match WNDCLASS wc; // Windows Class Structure DWORD dwExStyle; // Window Extended Style DWORD dwStyle; // Window Style RECT WindowRect; // Grabs Rectangle Upper Left / Lower Right Values WindowRect.left=(long)0; // Set Left Value To 0 WindowRect.right=(long)width; // Set Right Value To Requested Width WindowRect.top=(long)0; // Set Top Value To 0 WindowRect.bottom=(long)height; // Set Bottom Value To Requested Height fullscreen=fullscreenflag; // Set The Global Fullscreen Flag hInstance = GetModuleHandle(NULL); // Grab An Instance For Our Window wc.style = CS_HREDRAW | CS_VREDRAW | CS_OWNDC; // Redraw On Size, And Own DC For Window. wc.lpfnWndProc = (WNDPROC) WndProc; // WndProc Handles Messages wc.cbClsExtra = 0; // No Extra Window Data wc.cbWndExtra = 0; // No Extra Window Data wc.hInstance = hInstance; // Set The Instance wc.hIcon = LoadIcon(NULL, IDI_WINLOGO); // Load The Default Icon wc.hCursor = LoadCursor(NULL, IDC_ARROW); // Load The Arrow Pointer wc.hbrBackground = NULL; // No Background Required For GL wc.lpszMenuName = NULL; // We Don't Want A Menu wc.lpszClassName = "OpenGL"; // Set The Class Name if (!RegisterClass(&wc)) // Attempt To Register The Window Class { MessageBox(NULL,"Failed To Register The Window Class.","ERROR",MB_OK|MB_ICONEXCLAMATION); return FALSE; // Return FALSE } if (fullscreen) // Attempt Fullscreen Mode? { DEVMODE dmScreenSettings; // Device Mode memset(&dmScreenSettings,0,sizeof(dmScreenSettings)); // Makes Sure Memory's Cleared dmScreenSettings.dmSize=sizeof(dmScreenSettings); // Size Of The Devmode Structure dmScreenSettings.dmPelsWidth = width; // Selected Screen Width dmScreenSettings.dmPelsHeight = height; // Selected Screen Height dmScreenSettings.dmBitsPerPel = bits; // Selected Bits Per Pixel dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT; // Try To Set Selected Mode And Get Results. NOTE: CDS_FULLSCREEN Gets Rid Of Start Bar. if (ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL) { // If The Mode Fails, Offer Two Options. Quit Or Use Windowed Mode. if (MessageBox(NULL,"The Requested Fullscreen Mode Is Not Supported By\nYour Video Card. Use Windowed Mode Instead?","NeHe GL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES) { fullscreen=FALSE; // Windowed Mode Selected. Fullscreen = FALSE } else { // Pop Up A Message Box Letting User Know The Program Is Closing. MessageBox(NULL,"Program Will Now Close.","ERROR",MB_OK|MB_ICONSTOP); return FALSE; // Return FALSE } } } if (fullscreen) // Are We Still In Fullscreen Mode? { dwExStyle=WS_EX_APPWINDOW; // Window Extended Style dwStyle=WS_POPUP; // Windows Style ShowCursor(FALSE); // Hide Mouse Pointer } else { dwExStyle=WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; // Window Extended Style dwStyle=WS_OVERLAPPEDWINDOW; // Windows Style } AdjustWindowRectEx(&WindowRect, dwStyle, FALSE, dwExStyle); // Adjust Window To True Requested Size // Create The Window if (!(hWnd=CreateWindowEx( dwExStyle, // Extended Style For The Window "OpenGL", // Class Name title, // Window Title dwStyle | // Defined Window Style WS_CLIPSIBLINGS | // Required Window Style WS_CLIPCHILDREN, // Required Window Style 0, 0, // Window Position WindowRect.right-WindowRect.left, // Calculate Window Width WindowRect.bottom-WindowRect.top, // Calculate Window Height NULL, // No Parent Window NULL, // No Menu hInstance, // Instance NULL))) // Dont Pass Anything To WM_CREATE { KillGLWindow(); // Reset The Display MessageBox(NULL,"Window Creation Error.","ERROR",MB_OK|MB_ICONEXCLAMATION); return FALSE; // Return FALSE } static PIXELFORMATDESCRIPTOR pfd= // pfd Tells Windows How We Want Things To Be { sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor 1, // Version Number PFD_DRAW_TO_WINDOW | // Format Must Support Window PFD_SUPPORT_OPENGL | // Format Must Support OpenGL PFD_DOUBLEBUFFER, // Must Support Double Buffering PFD_TYPE_RGBA, // Request An RGBA Format bits, // Select Our Color Depth 0, 0, 0, 0, 0, 0, // Color Bits Ignored 0, // No Alpha Buffer 0, // Shift Bit Ignored 0, // No Accumulation Buffer 0, 0, 0, 0, // Accumulation Bits Ignored 16, // 16Bit Z-Buffer (Depth Buffer) 0, // No Stencil Buffer 0, // No Auxiliary Buffer PFD_MAIN_PLANE, // Main Drawing Layer 0, // Reserved 0, 0, 0 // Layer Masks Ignored }; if (!(hDC=GetDC(hWnd))) // Did We Get A Device Context? { KillGLWindow(); // Reset The Display MessageBox(NULL,"Can't Create A GL Device Context.","ERROR",MB_OK|MB_ICONEXCLAMATION); return FALSE; // Return FALSE } if (!(PixelFormat=ChoosePixelFormat(hDC,&pfd))) // Did Windows Find A Matching Pixel Format? { KillGLWindow(); // Reset The Display MessageBox(NULL,"Can't Find A Suitable PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION); return FALSE; // Return FALSE } if(!SetPixelFormat(hDC,PixelFormat,&pfd)) // Are We Able To Set The Pixel Format? { KillGLWindow(); // Reset The Display MessageBox(NULL,"Can't Set The PixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION); return FALSE; // Return FALSE } if (!(hRC=wglCreateContext(hDC))) // Are We Able To Get A Rendering Context? { KillGLWindow(); // Reset The Display MessageBox(NULL,"Can't Create A GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION); return FALSE; // Return FALSE } if(!wglMakeCurrent(hDC,hRC)) // Try To Activate The Rendering Context { KillGLWindow(); // Reset The Display MessageBox(NULL,"Can't Activate The GL Rendering Context.","ERROR",MB_OK|MB_ICONEXCLAMATION); return FALSE; // Return FALSE } ShowWindow(hWnd,SW_SHOW); // Show The Window SetForegroundWindow(hWnd); // Slightly Higher Priority SetFocus(hWnd); // Sets Keyboard Focus To The Window ReSizeGLScene(width, height); // Set Up Our Perspective GL Screen if (!InitGL()) // Initialize Our Newly Created GL Window { KillGLWindow(); // Reset The Display MessageBox(NULL,"Initialization Failed.","ERROR",MB_OK|MB_ICONEXCLAMATION); return FALSE; // Return FALSE } return TRUE; // Success}LRESULT CALLBACK WndProc( HWND hWnd, // Handle For This Window UINT uMsg, // Message For This Window WPARAM wParam, // Additional Message Information LPARAM lParam) // Additional Message Information{ switch (uMsg) // Check For Windows Messages { case WM_ACTIVATE: // Watch For Window Activate Message { if (!HIWORD(wParam)) // Check Minimization State { active=TRUE; // Program Is Active } else { active=FALSE; // Program Is No Longer Active } return 0; // Return To The Message Loop } case WM_SYSCOMMAND: // Intercept System Commands { switch (wParam) // Check System Calls { case SC_SCREENSAVE: // Screensaver Trying To Start? case SC_MONITORPOWER: // Monitor Trying To Enter Powersave? return 0; // Prevent From Happening } break; // Exit } case WM_CLOSE: // Did We Receive A Close Message? { PostQuitMessage(0); // Send A Quit Message return 0; // Jump Back } case WM_KEYDOWN: // Is A Key Being Held Down? { keys[wParam] = TRUE; // If So, Mark It As TRUE return 0; // Jump Back } case WM_KEYUP: // Has A Key Been Released? { keys[wParam] = FALSE; // If So, Mark It As FALSE return 0; // Jump Back } case WM_SIZE: // Resize The OpenGL Window { ReSizeGLScene(LOWORD(lParam),HIWORD(lParam)); // LoWord=Width, HiWord=Height return 0; // Jump Back } } // Pass All Unhandled Messages To DefWindowProc return DefWindowProc(hWnd,uMsg,wParam,lParam);}int WINAPI WinMain( HINSTANCE hInstance, // Instance HINSTANCE hPrevInstance, // Previous Instance LPSTR lpCmdLine, // Command Line Parameters int nCmdShow) // Window Show State{ MSG msg; // Windows Message Structure BOOL done=FALSE; // Bool Variable To Exit Loop // Ask The User Which Screen Mode They Prefer if (MessageBox(NULL,"Would You Like To Run In Fullscreen Mode?", "Start FullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO) { fullscreen=FALSE; // Windowed Mode } // Create Our OpenGL Window if (!CreateGLWindow("NeHe's Textures, Lighting & Keyboard Tutorial",640,480,16,fullscreen)) { return 0; // Quit If Window Was Not Created } while(!done) // Loop That Runs While done=FALSE { if (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) // Is There A Message Waiting? { if (msg.message==WM_QUIT) // Have We Received A Quit Message? { done=TRUE; // If So done=TRUE } else // If Not, Deal With Window Messages { TranslateMessage(&msg); // Translate The Message DispatchMessage(&msg); // Dispatch The Message } } else // If There Are No Messages { // Draw The Scene. Watch For ESC Key And Quit Messages From DrawGLScene() if ((active && !DrawGLScene()) || keys[VK_ESCAPE]) // Active? Was There A Quit Received? { done=TRUE; // ESC or DrawGLScene Signalled A Quit } else // Not Time To Quit, Update Screen { SwapBuffers(hDC); // Swap Buffers (Double Buffering) if (keys['L'] && !lp) { lp=TRUE; light=!light; if (!light) { glDisable(GL_LIGHTING); } else { glEnable(GL_LIGHTING); } } if (!keys['L']) { lp=FALSE; } if (keys['F'] && !fp) { fp=TRUE; filter+=1; if (filter>2) { filter=0; } } if (!keys['F']) { fp=FALSE; } if (keys[VK_PRIOR]) { z-=0.02f; } if (keys[VK_NEXT]) { z+=0.02f; } if (keys[VK_UP]) { xspeed-=0.01f; } if (keys[VK_DOWN]) { xspeed+=0.01f; } if (keys[VK_RIGHT]) { yspeed+=0.01f; } if (keys[VK_LEFT]) { yspeed-=0.01f; } if (keys[VK_F1]) // Is F1 Being Pressed? { keys[VK_F1]=FALSE; // If So Make Key FALSE KillGLWindow(); // Kill Our Current Window fullscreen=!fullscreen; // Toggle Fullscreen / Windowed Mode // Recreate Our OpenGL Window if (!CreateGLWindow("NeHe's Textures, Lighting & Keyboard Tutorial",640,480,16,fullscreen)) { return 0; // Quit If Window Was Not Created } } } } } // Shutdown KillGLWindow(); // Kill The Window return (msg.wParam); // Exit The Program}
这一课里还讲解了如何使用光照。他使用了两种不同的光。第一种称为环境光。环境光来自于四面八方。所有场景中的对象都处于环境光的照射中。第二种类型的光源叫做漫射光。漫射光由特定的光源产生，并在您的场景中的对象表面上产生反射。处于漫射光直接照射下的任何对象表面都变得很亮，而几乎未被照射到的区域就显得要暗一些。创建光源的过程和颜色的创建完全一致，先设置用来创建光源的数组。前三个参数分别是RGB三色分量，最后一个是alpha通道参数。
GLfloat LightAmbient[]= {
GLfloat LightDiffuse[]= {
最后保存光源的位置。前三个参数和glTranslate中的一样。依次分别是XYZ轴上的位移。最后一个参数取为
GLfloat LightPosition[]= {
教程里使用三种纹理滤波方式，第一种纹理（texture 0）使用gl_nearest（不光滑）滤波方式构建。第二种纹理（texture 1）使用gl_linear（线性滤波）方式，离屏幕越近的图像看起来就越光滑。第三种纹理 （texture 2）使用mipmapped滤波方式,这将创建一个外观十分优秀的纹理。
下面是创建纹理的新方法：Mip-mapping（纹理细化）。您可能会注意到当图像在屏幕上变得很小的时候，很多细节将会丢失。刚才还很不错的图案变得很难看。当您告诉OpenGL创建一个mipmapped的纹理后，OpenGL将尝试创建不同尺寸的高质量纹理。当您向屏幕绘制一个mipmapped纹理的时候，OpenGL将选择它已经创建的外观最佳的纹理（带有更多细节）来绘制，而不仅仅是缩放原先的图像（这将导致细节丢失）。
要绕过OpenGL对纹理宽度和高度所加的限制 （64、128、256等等）。办法就是 gluBuild2DMipmaps，我们可以使用任意的位图来创建纹理。OpenGL将自动将它缩放到正常的大小。
// 创建 MipMapped 纹理
glBindTexture(GL_TEXTURE_2D, texture[2]);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_NEAREST);
下面生成mipmapped纹理。我们使用三种颜色（红，绿，蓝）来生成一个2D纹理。TextureImage[0]->sizeX 是位图宽度，extureImage[0]->sizeY是位图高度，GL_RGB意味着我们依次使用RGB色彩。GL_UNSIGNED_BYTE意味着纹理数据的单位是字节。TextureImage[0]->data指向我们创建纹理所用的位图。
gluBuild2DMipmaps(GL_TEXTURE_2D, 3,
TextureImage[0]->sizeX, TextureImage[0]->sizeY,
GL_RGB, GL_UNSIGNED_BYTE, TextureImage[0]->data);
现在开始设置光源。下面一行设置环境光的发光量，光源light1开始发光：
glLightfv(GL_LIGHT1, GL_AMBIENT, LightAmbient); // 设置环境光
设置漫射光的发光量：
glLightfv(GL_LIGHT1, GL_DIFFUSE, LightDiffuse); // 设置漫射光
然后设置光源的位置：
glLightfv(GL_LIGHT1, GL_POSITION,LightPosition); // 光源位置
最后，我们启用一号光源，没有启用GL_LIGHTING，所以您看不见任何光线（只对光源进行设置、定位、甚至启用，光源都不会工作。除非我们启用GL_LIGHTING）。
glEnable(GL_LIGHT1); // 启用一号光源
课程中还学习了一个新的函数glNormal