BOOL CCY457OpenGLView::PreCreateWindow(CREATESTRUCT& cs)
{
// TODO: Modify the Window class or styles here by modifying
// the CREATESTRUCT cs
//An OpenGL Window must be created with the following flags
cs.style |= WS_CLIPSIBLINGS | WS_CLIPCHILDREN;
return CView::PreCreateWindow(cs);
}
4, 在CCY457OpenGLView.h中加入如下語句：
HGLRC m_hRC; //Rendering Context
CDC* m_pDC; //Device Context
BOOL InitializeOpenGL(); //Initialize OpenGL
BOOL SetupPixelFormat(); //Set up the Pixel Format
void RenderScene(); //Render the Scene
5, 在OnCreate中我們將通過建立像素格式和繪制上下文來初始化OpenGL. 在InitializeOpenGL()中會創(chuàng)建一個設(shè)備上下文(DC)，為這個DC選擇一個像素格式，創(chuàng)建和這個DC相關(guān)的繪制上下文（RC）,然后選擇這個RC.這個函數(shù)會調(diào)用SetupPixelFormat()來建立像素格式。
int CCY457OpenGLView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
if (CView::OnCreate(lpCreateStruct) == -1)
return -1;
//Initialize OpenGL Here
InitializeOpenGL();
return 0;
}
BOOL CCY457OpenGLView::InitializeOpenGL()
{
//Get a DC for the Client Area
m_pDC = new CClientDC(this);
//Failure to Get DC
if(m_pDC == NULL)
{
MessageBox("Error Obtaining DC");
return FALSE;
}
//Failure to set the pixel format
if(!SetupPixelFormat())
{
return FALSE;
}
//Create Rendering Context
m_hRC = ::wglCreateContext (m_pDC->GetSafeHdc ());
//Failure to Create Rendering Context
if(m_hRC == 0)
{
MessageBox("Error Creating RC");
return FALSE;
}
//Make the RC Current
if(::wglMakeCurrent (m_pDC->GetSafeHdc (), m_hRC)==FALSE)
{
MessageBox("Error making RC Current");
return FALSE;
}
//Specify Black as the clear color
::glClearColor(0.0f,0.0f,0.0f,0.0f);
//Specify the back of the buffer as clear depth
::glClearDepth(1.0f);
//Enable Depth Testing
::glEnable(GL_DEPTH_TEST);
return TRUE;
}
//Setup Pixel Format
/////////////////////////////////////////////////////////////////////////////
BOOL CCY457OpenGLView::SetupPixelFormat()
{
static PIXELFORMATDESCRIPTOR pfd =
{
sizeof(PIXELFORMATDESCRIPTOR), // size of this pfd
1, // version number
PFD_DRAW_TO_WINDOW | // support window
PFD_SUPPORT_OPENGL | // support OpenGL
PFD_DOUBLEBUFFER, // double buffered
PFD_TYPE_RGBA, // RGBA type
24, // 24-bit 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, // accum bits ignored
16, // 16-bit z-buffer
0, // no stencil buffer
0, // no auxiliary buffer
PFD_MAIN_PLANE, // main layer
0, // reserved
0, 0, 0 // layer masks ignored
};
int m_nPixelFormat = ::ChoosePixelFormat(m_pDC->GetSafeHdc(), &pfd);
if ( m_nPixelFormat == 0 )
{
return FALSE;
}
if ( ::SetPixelFormat(m_pDC->GetSafeHdc(), m_nPixelFormat, &pfd) == FALSE)
{
return FALSE;
}
return TRUE;
}
6, 在OnSize()中一般用來設(shè)置視口和視錐，因為這些是和窗口大小相關(guān)的。基本操作包括設(shè)置視口，選擇投影矩陣，設(shè)置模型視圖矩陣。
void CCY457OpenGLView::OnSize(UINT nType, int cx, int cy)
{
CView::OnSize(nType, cx, cy);
GLdouble aspect_ratio; // width/height ratio
if ( 0 >= cx || 0 >= cy )
{
return;
}
// select the full client area
::glViewport(0, 0, cx, cy);
// compute the aspect ratio
// this will keep all dimension scales equal
aspect_ratio = (GLdouble)cx/(GLdouble)cy;
// select the projection matrix and clear it
::glMatrixMode(GL_PROJECTION);
::glLoadIdentity();
// select the viewing volume
::gluPerspective(45.0f, aspect_ratio, .01f, 200.0f);
// switch back to the modelview matrix and clear it
::glMatrixMode(GL_MODELVIEW);
::glLoadIdentity();
}
7,在繪制場景時，一般包括如下步驟：1）清空緩存。2）繪制場景。3）Flush掉渲染流水線。4）若設(shè)置了雙緩沖，則交換前后臺緩沖區(qū)。
void CCY457OpenGLView::OnDraw(CDC* pDC)
{
CCY457OpenGLDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
// Clear out the color & depth buffers
::glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
RenderScene();
// Tell OpenGL to flush its pipeline
::glFinish();
// Now Swap the buffers
::SwapBuffers( m_pDC->GetSafeHdc() );
}
void CCY457OpenGLView::RenderScene ()
{//第一個玩具嘛，先空著，后面慢慢填
}
8，試試改變窗口的大小，你會看到很嚴重的閃爍，并且關(guān)閉程序后會報告內(nèi)存泄露，因此我們這就來解決這兩個問題吧。
發(fā)生閃爍的原因是Windows先繪制背景，然后再是OpenGL繪制，因為我們已經(jīng)讓OpenGL負責(zé)清空背景色，因此我們不需要Windows去清空背景了
BOOL CCY457OpenGLView::OnEraseBkgnd(CDC* pDC)
{
//Tell Windows not to erase the background
return TRUE;
}
內(nèi)存泄露的原因是我們在SetupPixelFormat（）中使用了new運算符來為CClientDC對象分配內(nèi)存，因此需要顯示delete掉。
void CCY457OpenGLView::OnDestroy()
{
CView::OnDestroy();
//Make the RC non-current
if(::wglMakeCurrent (0,0) == FALSE)
{
MessageBox("Could not make RC non-current");
}
//Delete the rendering context
if(::wglDeleteContext (m_hRC)==FALSE)
{
MessageBox("Could not delete RC");
}
//Delete the DC
if(m_pDC)
{
delete m_pDC;
}
//Set it to NULL
m_pDC = NULL;
}