OpenGL入门笔记（七）

OpenGL中的绝大多数特效都与某些类型的（色彩）混合有关。混色的定义为，将某个象素的颜色和已绘制在屏幕上与其对应的象素颜色相互结合。至于如何结合这两个颜色则依赖于颜色的alpha通道的分量值，以及/或者所使用的混色函数。Alpha通常是位于颜色值末尾的第4个颜色组成分量。前面这些课我们都是用GL_RGB来指定颜色的三个分量。相应的GL_RGBA可以指定alpha分量的值。更进一步，我们可以使用glColor<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="False" sourcevalue="4" unitname="F">4f</chmetcnv>()来代替glColor<chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="False" sourcevalue="3" unitname="F">3f</chmetcnv>()。<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

　　 绝大多数人都认为Alpha分量代表材料的透明度。这就是说，alpha值为0.0时所代表的材料是完全透明的。alpha值为1.0时所代表的材料则是完全不透明的。

混合的基本原理是就将要分色的图像各象素的颜色以及背景颜色均按照RGB规则各自分离之后，根据 — 图像的RGB颜色分量*alpha值+背景的RGB颜色分量*(1-alpha值) — 这样一个简单公式来混合之后，最后将混合得到的RGB分量重新合并。）公式如下：

(Rs Sr + Rd Dr, Gs Sg + Gd Dg, Bs Sb + Bd Db, As Sa + Ad Da)

　　 OpenGL按照上面的公式计算这两个象素的混色结果。小写的s和r分别代表源象素和目标象素。大写的S和D则是相应的混色因子。这些决定了您如何对这些象素混色。绝大多数情况下，各颜色通道的alpha混色值大小相同，这样对源象素就有(As, As, As, As)，目标象素则有(1, 1, 1, 1) - (As, As, As, As)。上面的公式就成了下面的模样：

(Rs As + Rd (1 - As), Gs As + Gd (1 - As), Bs As + Bs (1 - As), As As + Ad (1 - As))

这个公式会生成透明/半透明的效果。

在OpenGL中首先我们得打开混合， 然后设置混合式。在绘制透明物体的时候， 我们关闭深度缓存， 因为我们仍然希望在半透明物体后面的物体能被绘制。 这并不是使用混合的正确方式， 但是在情况简单的时候它会工作得很好。正确的混色过程应该是先绘制全部的场景之后再绘制透明的图形。并且要按照与深度缓存相反的次序来绘制（先画最远的物体）。考虑对两个多边形（1和2）进行alpha混合，不同的绘制次序会得到不同的结果。（这里假定多边形1离观察者最近，那么正确的过程应该先画多边形2，再画多边形1。正如您再现实中所见到的那样，从这两个“透明的”多边形背后照射来的光线总是先穿过多边形2，再穿过多边形1，最后才到达观察者的眼睛）。 在深度缓存启用时，您应该将透明图形按照深度进行排序，并在全部场景绘制完毕之后再绘制这些透明物体。否则您将得到不正确的结果。

demo8
<!--<br><br>Code highlighting produced by Actipro CodeHighlighter (freeware)<br>http://www.CodeHighlighter.com/<br><br>-->#include<windows.h>//HeaderFileForWindows
#include<stdio.h>//HeaderFileForStandardInput/Output
#include<gl/gl.h>//HeaderFileForTheOpenGL32Library
#include<gl/glu.h>//HeaderFileForTheGLu32Library
#include<gl/glaux.h>//HeaderFileForTheGlauxLibrary

HDChDC=NULL;//PrivateGDIDeviceContext
HGLRChRC=NULL;//PermanentRenderingContext
HWNDhWnd=NULL;//HoldsOurWindowHandle
HINSTANCEhInstance;//HoldsTheInstanceOfTheApplication

boolkeys[256];//ArrayUsedForTheKeyboardRoutine
boolactive=TRUE;//WindowActiveFlagSetToTRUEByDefault
boolfullscreen=TRUE;//FullscreenFlagSetToFullscreenModeByDefault
boollight;//LightingON/OFF
boolblend;//BlendingOFF/ON?(NEW)
boollp;//LPressed?
boolfp;//FPressed?
boolbp;//BPressed?(NEW)

GLfloatxrot;//XRotation
GLfloatyrot;//YRotation
GLfloatxspeed;//XRotationSpeed
GLfloatyspeed;//YRotationSpeed
GLfloatz=-5.0f;//DepthIntoTheScreen

GLfloatLightAmbient[]={0.5f,0.5f,0.5f,1.0f};
GLfloatLightDiffuse[]={1.0f,1.0f,1.0f,1.0f};
GLfloatLightPosition[]={0.0f,0.0f,2.0f,1.0f};

GLuintfilter;//WhichFilterToUse
GLuinttexture[3];//StorageFor3Textures

LRESULTCALLBACKWndProc(HWND,UINT,WPARAM,LPARAM);//DeclarationForWndProc

AUX_RGBImageRec*LoadBMP(char*Filename)//LoadsABitmapImage
{
FILE*File=NULL;//FileHandle

if(!Filename)//MakeSureAFilenameWasGiven
{
returnNULL;//IfNotReturnNULL
}

File=fopen(Filename,"r");//CheckToSeeIfTheFileExists

if(File)//DoesTheFileExist?
{
fclose(File);//CloseTheHandle
returnauxDIBImageLoad(Filename);//LoadTheBitmapAndReturnAPointer
}

returnNULL;//IfLoadFailedReturnNULL
}

intLoadGLTextures()//LoadBitmapsAndConvertToTextures
{
intStatus=FALSE;//StatusIndicator

AUX_RGBImageRec*TextureImage[1];//CreateStorageSpaceForTheTexture

memset(TextureImage,0,sizeof(void*)*1);//SetThePointerToNULL

//LoadTheBitmap,CheckForErrors,IfBitmap'sNotFoundQuit
if(TextureImage[0]=LoadBMP("Data/glass.bmp"))
{
Status=TRUE;//SetTheStatusToTRUE

glGenTextures(3,&texture[0]);//CreateThreeTextures

//CreateNearestFilteredTexture
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);

//CreateLinearFilteredTexture
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);

//CreateMipMappedTexture
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])//IfTextureExists
{
if(TextureImage[0]->data)//IfTextureImageExists
{
free(TextureImage[0]->data);//FreeTheTextureImageMemory
}

free(TextureImage[0]);//FreeTheImageStructure
}

returnStatus;//ReturnTheStatus
}

GLvoidReSizeGLScene(GLsizeiwidth,GLsizeiheight)//ResizeAndInitializeTheGLWindow
{
if(height==0)//PreventADivideByZeroBy
{
height=1;//MakingHeightEqualOne
}

glViewport(0,0,width,height);//ResetTheCurrentViewport

glMatrixMode(GL_PROJECTION);//SelectTheProjectionMatrix
glLoadIdentity();//ResetTheProjectionMatrix

//CalculateTheAspectRatioOfTheWindow
gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

glMatrixMode(GL_MODELVIEW);//SelectTheModelviewMatrix
glLoadIdentity();//ResetTheModelviewMatrix
}

intInitGL(GLvoid)//AllSetupForOpenGLGoesHere
{
if(!LoadGLTextures())//JumpToTextureLoadingRoutine
{
returnFALSE;//IfTextureDidn'tLoadReturnFALSE
}

glEnable(GL_TEXTURE_2D);//EnableTextureMapping
glShadeModel(GL_SMOOTH);//EnableSmoothShading
glClearColor(0.0f,0.0f,0.0f,0.5f);//BlackBackground
glClearDepth(1.0f);//DepthBufferSetup
glEnable(GL_DEPTH_TEST);//EnablesDepthTesting
glDepthFunc(GL_LEQUAL);//TheTypeOfDepthTestingToDo
glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST);//ReallyNicePerspectiveCalculations

glLightfv(GL_LIGHT1,GL_AMBIENT,LightAmbient);//SetupTheAmbientLight
glLightfv(GL_LIGHT1,GL_DIFFUSE,LightDiffuse);//SetupTheDiffuseLight
glLightfv(GL_LIGHT1,GL_POSITION,LightPosition);//PositionTheLight
glEnable(GL_LIGHT1);//EnableLightOne

glColor4f(1.0f,1.0f,1.0f,0.5);//FullBrightness.50%Alpha
glBlendFunc(GL_SRC_ALPHA,GL_ONE);//SetTheBlendingFunctionForTranslucency

returnTRUE;//InitializationWentOK
}

intDrawGLScene(GLvoid)//Here'sWhereWeDoAllTheDrawing
{
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);//ClearTheScreenAndTheDepthBuffer
glLoadIdentity();//ResetTheView
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);
//FrontFace
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);
//BackFace
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);
//TopFace
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);
//BottomFace
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);
//Rightface
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);
//LeftFace
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;
returnTRUE;//KeepGoing
}

GLvoidKillGLWindow(GLvoid)//ProperlyKillTheWindow
{
if(fullscreen)//AreWeInFullscreenMode?
{
ChangeDisplaySettings(NULL,0);//IfSoSwitchBackToTheDesktop
ShowCursor(TRUE);//ShowMousePointer
}

if(hRC)//DoWeHaveARenderingContext?
{
if(!wglMakeCurrent(NULL,NULL))//AreWeAbleToReleaseTheDCAndRCContexts?
{
MessageBox(NULL,"ReleaseOfDCAndRCFailed.","SHUTDOWNERROR",MB_OK|MB_ICONINFORMATION);
}

if(!wglDeleteContext(hRC))//AreWeAbleToDeleteTheRC?
{
MessageBox(NULL,"ReleaseRenderingContextFailed.","SHUTDOWNERROR",MB_OK|MB_ICONINFORMATION);
}
hRC=NULL;//SetRCToNULL
}

if(hDC&&!ReleaseDC(hWnd,hDC))//AreWeAbleToReleaseTheDC
{
MessageBox(NULL,"ReleaseDeviceContextFailed.","SHUTDOWNERROR",MB_OK|MB_ICONINFORMATION);
hDC=NULL;//SetDCToNULL
}

if(hWnd&&!DestroyWindow(hWnd))//AreWeAbleToDestroyTheWindow?
{
MessageBox(NULL,"CouldNotReleasehWnd.","SHUTDOWNERROR",MB_OK|MB_ICONINFORMATION);
hWnd=NULL;//SethWndToNULL
}

if(!UnregisterClass("OpenGL",hInstance))//AreWeAbleToUnregisterClass
{
MessageBox(NULL,"CouldNotUnregisterClass.","SHUTDOWNERROR",MB_OK|MB_ICONINFORMATION);
hInstance=NULL;//SethInstanceToNULL
}
}

/**//*ThisCodeCreatesOurOpenGLWindow.ParametersAre:*
*title-TitleToAppearAtTheTopOfTheWindow*
*width-WidthOfTheGLWindowOrFullscreenMode*
*height-HeightOfTheGLWindowOrFullscreenMode*
*bits-NumberOfBitsToUseForColor(8/16/24/32)*
*fullscreenflag-UseFullscreenMode(TRUE)OrWindowedMode(FALSE)*/

BOOLCreateGLWindow(char*title,intwidth,intheight,intbits,boolfullscreenflag)
{
GLuintPixelFormat;//HoldsTheResultsAfterSearchingForAMatch
WNDCLASSwc;//WindowsClassStructure
DWORDdwExStyle;//WindowExtendedStyle
DWORDdwStyle;//WindowStyle
RECTWindowRect;//GrabsRectangleUpperLeft/LowerRightValues
WindowRect.left=(long)0;//SetLeftValueTo0
WindowRect.right=(long)width;//SetRightValueToRequestedWidth
WindowRect.top=(long)0;//SetTopValueTo0
WindowRect.bottom=(long)height;//SetBottomValueToRequestedHeight

fullscreen=fullscreenflag;//SetTheGlobalFullscreenFlag

hInstance=GetModuleHandle(NULL);//GrabAnInstanceForOurWindow
wc.style=CS_HREDRAW|CS_VREDRAW|CS_OWNDC;//RedrawOnSize,AndOwnDCForWindow.
wc.lpfnWndProc=(WNDPROC)WndProc;//WndProcHandlesMessages
wc.cbClsExtra=0;//NoExtraWindowData
wc.cbWndExtra=0;//NoExtraWindowData
wc.hInstance=hInstance;//SetTheInstance
wc.hIcon=LoadIcon(NULL,IDI_WINLOGO);//LoadTheDefaultIcon
wc.hCursor=LoadCursor(NULL,IDC_ARROW);//LoadTheArrowPointer
wc.hbrBackground=NULL;//NoBackgroundRequiredForGL
wc.lpszMenuName=NULL;//WeDon'tWantAMenu
wc.lpszClassName="OpenGL";//SetTheClassName

if(!RegisterClass(&wc))//AttemptToRegisterTheWindowClass
{
MessageBox(NULL,"FailedToRegisterTheWindowClass.","ERROR",MB_OK|MB_ICONEXCLAMATION);
returnFALSE;//ReturnFALSE
}

if(fullscreen)//AttemptFullscreenMode?
{
DEVMODEdmScreenSettings;//DeviceMode
memset(&dmScreenSettings,0,sizeof(dmScreenSettings));//MakesSureMemory'sCleared
dmScreenSettings.dmSize=sizeof(dmScreenSettings);//SizeOfTheDevmodeStructure
dmScreenSettings.dmPelsWidth=width;//SelectedScreenWidth
dmScreenSettings.dmPelsHeight=height;//SelectedScreenHeight
dmScreenSettings.dmBitsPerPel=bits;//SelectedBitsPerPixel
dmScreenSettings.dmFields=DM_BITSPERPEL|DM_PELSWIDTH|DM_PELSHEIGHT;

//TryToSetSelectedModeAndGetResults.NOTE:CDS_FULLSCREENGetsRidOfStartBar.
if(ChangeDisplaySettings(&dmScreenSettings,CDS_FULLSCREEN)!=DISP_CHANGE_SUCCESSFUL)
{
//IfTheModeFails,OfferTwoOptions.QuitOrUseWindowedMode.
if(MessageBox(NULL,"TheRequestedFullscreenModeIsNotSupportedBy/nYourVideoCard.UseWindowedModeInstead?","NeHeGL",MB_YESNO|MB_ICONEXCLAMATION)==IDYES)
{
fullscreen=FALSE;//WindowedModeSelected.Fullscreen=FALSE
}
else
{
//PopUpAMessageBoxLettingUserKnowTheProgramIsClosing.
MessageBox(NULL,"ProgramWillNowClose.","ERROR",MB_OK|MB_ICONSTOP);
returnFALSE;//ReturnFALSE
}
}
}

if(fullscreen)//AreWeStillInFullscreenMode?
{
dwExStyle=WS_EX_APPWINDOW;//WindowExtendedStyle
dwStyle=WS_POPUP;//WindowsStyle
ShowCursor(FALSE);//HideMousePointer
}
else
{
dwExStyle=WS_EX_APPWINDOW|WS_EX_WINDOWEDGE;//WindowExtendedStyle
dwStyle=WS_OVERLAPPEDWINDOW;//WindowsStyle
}

AdjustWindowRectEx(&WindowRect,dwStyle,FALSE,dwExStyle);//AdjustWindowToTrueRequestedSize

//CreateTheWindow
if(!(hWnd=CreateWindowEx(dwExStyle,//ExtendedStyleForTheWindow
"OpenGL",//ClassName
title,//WindowTitle
dwStyle|//DefinedWindowStyle
WS_CLIPSIBLINGS|//RequiredWindowStyle
WS_CLIPCHILDREN,//RequiredWindowStyle
0,0,//WindowPosition
WindowRect.right-WindowRect.left,//CalculateWindowWidth
WindowRect.bottom-WindowRect.top,//CalculateWindowHeight
NULL,//NoParentWindow
NULL,//NoMenu
hInstance,//Instance
NULL)))//DontPassAnythingToWM_CREATE
{
KillGLWindow();//ResetTheDisplay
MessageBox(NULL,"WindowCreationError.","ERROR",MB_OK|MB_ICONEXCLAMATION);
returnFALSE;//ReturnFALSE
}

staticPIXELFORMATDESCRIPTORpfd=//pfdTellsWindowsHowWeWantThingsToBe
{
sizeof(PIXELFORMATDESCRIPTOR),//SizeOfThisPixelFormatDescriptor
1,//VersionNumber
PFD_DRAW_TO_WINDOW|//FormatMustSupportWindow
PFD_SUPPORT_OPENGL|//FormatMustSupportOpenGL
PFD_DOUBLEBUFFER,//MustSupportDoubleBuffering
PFD_TYPE_RGBA,//RequestAnRGBAFormat
bits,//SelectOurColorDepth
0,0,0,0,0,0,//ColorBitsIgnored
0,//NoAlphaBuffer
0,//ShiftBitIgnored
0,//NoAccumulationBuffer
0,0,0,0,//AccumulationBitsIgnored
16,//16BitZ-Buffer(DepthBuffer)
0,//NoStencilBuffer
0,//NoAuxiliaryBuffer
PFD_MAIN_PLANE,//MainDrawingLayer
0,//Reserved
0,0,0//LayerMasksIgnored
};

if(!(hDC=GetDC(hWnd)))//DidWeGetADeviceContext?
{
KillGLWindow();//ResetTheDisplay
MessageBox(NULL,"Can'tCreateAGLDeviceContext.","ERROR",MB_OK|MB_ICONEXCLAMATION);
returnFALSE;//ReturnFALSE
}

if(!(PixelFormat=ChoosePixelFormat(hDC,&pfd)))//DidWindowsFindAMatchingPixelFormat?
{
KillGLWindow();//ResetTheDisplay
MessageBox(NULL,"Can'tFindASuitablePixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
returnFALSE;//ReturnFALSE
}

if(!SetPixelFormat(hDC,PixelFormat,&pfd))//AreWeAbleToSetThePixelFormat?
{
KillGLWindow();//ResetTheDisplay
MessageBox(NULL,"Can'tSetThePixelFormat.","ERROR",MB_OK|MB_ICONEXCLAMATION);
returnFALSE;//ReturnFALSE
}

if(!(hRC=wglCreateContext(hDC)))//AreWeAbleToGetARenderingContext?
{
KillGLWindow();//ResetTheDisplay
MessageBox(NULL,"Can'tCreateAGLRenderingContext.","ERROR",MB_OK|MB_ICONEXCLAMATION);
returnFALSE;//ReturnFALSE
}

if(!wglMakeCurrent(hDC,hRC))//TryToActivateTheRenderingContext
{
KillGLWindow();//ResetTheDisplay
MessageBox(NULL,"Can'tActivateTheGLRenderingContext.","ERROR",MB_OK|MB_ICONEXCLAMATION);
returnFALSE;//ReturnFALSE
}

ShowWindow(hWnd,SW_SHOW);//ShowTheWindow
SetForegroundWindow(hWnd);//SlightlyHigherPriority
SetFocus(hWnd);//SetsKeyboardFocusToTheWindow
ReSizeGLScene(width,height);//SetUpOurPerspectiveGLScreen

if(!InitGL())//InitializeOurNewlyCreatedGLWindow
{
KillGLWindow();//ResetTheDisplay
MessageBox(NULL,"InitializationFailed.","ERROR",MB_OK|MB_ICONEXCLAMATION);
returnFALSE;//ReturnFALSE
}

returnTRUE;//Success
}

LRESULTCALLBACKWndProc(HWNDhWnd,//HandleForThisWindow
UINTuMsg,//MessageForThisWindow
WPARAMwParam,//AdditionalMessageInformation
LPARAMlParam)//AdditionalMessageInformation
{
switch(uMsg)//CheckForWindowsMessages
{
caseWM_ACTIVATE://WatchForWindowActivateMessage
{
if(!HIWORD(wParam))//CheckMinimizationState
{
active=TRUE;//ProgramIsActive
}
else
{
active=FALSE;//ProgramIsNoLongerActive
}

return0;//ReturnToTheMessageLoop
}

caseWM_SYSCOMMAND://InterceptSystemCommands
{
switch(wParam)//CheckSystemCalls
{
caseSC_SCREENSAVE://ScreensaverTryingToStart?
caseSC_MONITORPOWER://MonitorTryingToEnterPowersave?
return0;//PreventFromHappening
}
break;//Exit
}

caseWM_CLOSE://DidWeReceiveACloseMessage?
{
PostQuitMessage(0);//SendAQuitMessage
return0;//JumpBack
}

caseWM_KEYDOWN://IsAKeyBeingHeldDown?
{
keys[wParam]=TRUE;//IfSo,MarkItAsTRUE
return0;//JumpBack
}

caseWM_KEYUP://HasAKeyBeenReleased?
{
keys[wParam]=FALSE;//IfSo,MarkItAsFALSE
return0;//JumpBack
}

caseWM_SIZE://ResizeTheOpenGLWindow
{
ReSizeGLScene(LOWORD(lParam),HIWORD(lParam));//LoWord=Width,HiWord=Height
return0;//JumpBack
}
}

//PassAllUnhandledMessagesToDefWindowProc
returnDefWindowProc(hWnd,uMsg,wParam,lParam);
}

intWINAPIWinMain(HINSTANCEhInstance,//Instance
HINSTANCEhPrevInstance,//PreviousInstance
LPSTRlpCmdLine,//CommandLineParameters
intnCmdShow)//WindowShowState
{
MSGmsg;//WindowsMessageStructure
BOOLdone=FALSE;//BoolVariableToExitLoop

//AskTheUserWhichScreenModeTheyPrefer
if(MessageBox(NULL,"WouldYouLikeToRunInFullscreenMode?","StartFullScreen?",MB_YESNO|MB_ICONQUESTION)==IDNO)
{
fullscreen=FALSE;//WindowedMode
}

//CreateOurOpenGLWindow
if(!CreateGLWindow("TomStanis&NeHe'sBlendingTutorial",640,480,16,fullscreen))
{
return0;//QuitIfWindowWasNotCreated
}

while(!done)//LoopThatRunsWhiledone=FALSE
{
if(PeekMessage(&msg,NULL,0,0,PM_REMOVE))//IsThereAMessageWaiting?
{
if(msg.message==WM_QUIT)//HaveWeReceivedAQuitMessage?
{
done=TRUE;//IfSodone=TRUE
}
else//IfNot,DealWithWindowMessages
{
TranslateMessage(&msg);//TranslateTheMessage
DispatchMessage(&msg);//DispatchTheMessage
}
}
else//IfThereAreNoMessages
{
//DrawTheScene.WatchForESCKeyAndQuitMessagesFromDrawGLScene()
if((active&&!DrawGLScene())||keys[VK_ESCAPE])//Active?WasThereAQuitReceived?
{
done=TRUE;//ESCorDrawGLSceneSignalledAQuit
}
else//NotTimeToQuit,UpdateScreen
{
SwapBuffers(hDC);//SwapBuffers(DoubleBuffering)
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;
}
//BlendingCodeStartsHere
if(keys['B']&&!bp)
{
bp=TRUE;
blend=!blend;
if(blend)
{
glEnable(GL_BLEND);//TurnBlendingOn
glDisable(GL_DEPTH_TEST);//TurnDepthTestingOff
}
else
{
glDisable(GL_BLEND);//TurnBlendingOff
glEnable(GL_DEPTH_TEST);//TurnDepthTestingOn
}
}
if(!keys['B'])
{
bp=FALSE;
}
//BlendingCodeEndsHere

if(keys[VK_F1])//IsF1BeingPressed?
{
keys[VK_F1]=FALSE;//IfSoMakeKeyFALSE
KillGLWindow();//KillOurCurrentWindow
fullscreen=!fullscreen;//ToggleFullscreen/WindowedMode
//RecreateOurOpenGLWindow
if(!CreateGLWindow("TomStanis&NeHe'sBlendingTutorial",640,480,16,fullscreen))
{
return0;//QuitIfWindowWasNotCreated
}
}
}
}
}

//Shutdown
KillGLWindow();//KillTheWindow
return(msg.wParam);//ExitTheProgram
}