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())                                // Jump To Texture Loading Routine ( NEW )
    {
        return FALSE;                                    // If Texture Didn't Load Return FALSE
    }
    glEnable(GL_TEXTURE_2D);                            // Enable Texture Mapping ( 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);                            // Enable Smooth Shading
    //COLORREF color = ::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);                // 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

    glColor4f(1.0f, 1.0f, 1.0f, 0.5);                    // Full Brightness.  50% Alpha
    glBlendFunc(GL_SRC_ALPHA,GL_ONE);                    // Set The Blending Function For Translucency


    return TRUE;                                        // Initialization Went OK
}

最后在voidCOpenGLDemoView::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);            // Turn Blending On
                    glDisable(GL_DEPTH_TEST);    // Turn Depth Testing Off
                }
                else
                {
                    glDisable(GL_BLEND);        // Turn Blending Off
                    glEnable(GL_DEPTH_TEST);    // Turn Depth Testing On
                }
            }
            bPressed = FALSE;

        break;
    }

最终效果如图所示：