OpenGL中的混合(Blending)

这篇是在上一篇的基础上修改而来的，对应着Nehe教程的第8课，代码仍然采用MFC框架来实现。

其中InitGL需要做些修改，加入混合操作所需要的代码：

BOOLCOpenGLDemoView::InitGL(GLvoid)
{
if(!LoadGLTextures())//JumpToTextureLoadingRoutine(NEW)
{
returnFALSE;//IfTextureDidn'tLoadReturnFALSE
}
glEnable(GL_TEXTURE_2D);//EnableTextureMapping(NEW)

glLightfv(GL_LIGHT1,GL_AMBIENT,LightAmbient);//设置环境光
glLightfv(GL_LIGHT1,GL_DIFFUSE,LightDiffuse);//设置漫射光
glLightfv(GL_LIGHT1,GL_POSITION,LightPosition);//设置光源位置
glEnable(GL_LIGHT1);//启用一号光源

glShadeModel(GL_SMOOTH);//EnableSmoothShading
//COLORREFcolor=::GetSysColor(COLOR_3DFACE);
//glClearColor((float)GetRValue(color)/255.0f,
//(float)GetGValue(color)/255.0f,
//(float)GetBValue(color)/255.0f,
//1.0);
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

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

returnTRUE;//InitializationWentOK
}

最后在void COpenGLDemoView::OnKeyUp(UINT nChar, UINT nRepCnt, UINT nFlags)中加入对B按键的事件处理代码：

case'B':
{
if(bPressed==TRUE)
{//防止长时间按着'B'键而导致持续混合变化
bLighting=!bLighting;
if(bLighting)
{
glEnable(GL_BLEND);//TurnBlendingOn
glDisable(GL_DEPTH_TEST);//TurnDepthTestingOff
}
else
{
glDisable(GL_BLEND);//TurnBlendingOff
glEnable(GL_DEPTH_TEST);//TurnDepthTestingOn
}
}
bPressed=FALSE;

break;
}

最终效果如图所示：

OpenGL中的混合(Blending)