MFC下OpenGL入門
1， 建一工程文件，我這里命名為first，現在first工程里面我們沒有添加任何東西，所有的東西都是MFC自動幫我們創建的。
2， 添加鏈接庫。這一步很關鍵。打開菜單欄下的項目->屬性->配置屬性->鏈接器->輸入->附加依賴項里加入OpenGL32.lib GLu32.lib GLaux.lib，如圖
3， 加頭文件，在stdafx里面添加opengl的頭文件。如下代碼所示：
#include "stdio.h"
#include "math.h"
#include "gl\gl.h"
#include "gl\glu.h"
#include "gl\glaux.h"
//---------------------------------------------------------------------------<
4， CCY457OpenGLView類的屬性欄，為下述消息加入消息處理函數：WM_CREATE (for OnCreate), WM_DESTROY (for OnDestroy), WM_SIZE (for OnSize), WM_ERASEBACKGROUND (for OnEraseBkground).如下圖：
5， 設置窗口顯示風格。窗口創建之前我們必須設置窗口風格包含WS_CLIPCHILDREN和WS_CLIPSIBLINGS，從而避免OpenGL繪制到其他窗口中去。這些應該放在PreCreateWindow()中。
{
// TODO: 在此處通過修改
// CREATESTRUCT cs 來修改窗口類或樣式
cs.style |= WS_CLIPSIBLINGS | WS_CLIPCHILDREN;//Tramp
return CView::PreCreateWindow(cs);
}
6， 在CfirstView.h中加入如下語句：
/************************************************************************/
/* 設置的變量是Rendering Context(着色描述表)。每一個OpenGL都被連接到一個着
色描述表上。着色描述表將所有的OpenGL調用命令連接到Device Context(設備描述表)上。
我將OpenGL的着色描述表定義為hRC 。要讓您的程序能夠繪制窗口的話，還需要創建一個
設備描述表，也就是第二行的內容。Windows的設備描述表被定義為hDC 。DC將窗口連接到
GDI(Graphics Device Interface圖形設備接口)。而RC將OpenGL連接到DC */
/************************************************************************/
HGLRC m_hRC; //Rendering Context着色描述表
CDC* m_pDC; //Device Context設備描述表
BOOL InitializeOpenGL(); //Initialize OpenGL
BOOL SetupPixelFormat(); //Set up the Pixel Format
void RenderScene(); //Render the Scene
7， 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()中會創建一個設備上下文(DC)，為這個DC選擇一個像素格式，創建和這個DC相關的繪制上下文（RC）,然后選擇這個RC.這個函數會調用SetupPixelFormat()來建立像素格式。
int Clesson1View::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
if (CView::OnCreate(lpCreateStruct) == -1)
return -1;
// TODO: 在此添加您專用的創建代碼
InitializeOpenGL();//初始化openGL繪圖
return 0;
}
//初始化opengl繪制
BOOL CfirstView::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;
}
//設置像素格式
BOOL CfirstView::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;
}
8， 在OnSize()中一般用來設置視口和視錐，因為這些是和窗口大小相關的。基本操作包括設置視口，選擇投影矩陣，設置模型視圖矩陣。
void CfirstView::OnSize(UINT nType, int cx, int cy)
{
CView::OnSize(nType, cx, cy);
// TODO: 在此處添加消息處理程序代碼
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);//畫三維
//::gluOrtho2D(-10.0f, 10.0f, -10.0f, 10.0f); //二維
// switch back to the modelview matrix and clear it
::glMatrixMode(GL_MODELVIEW);
::glLoadIdentity();
}
9， 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）若設置了雙緩沖，則交換前后台緩沖區。
void CfirstView::OnDraw(CDC* /*pDC*/)
{
CfirstDoc* pDoc = GetDocument();
ASSERT_VALID(pDoc);
if (!pDoc)
return;
// TODO: 在此處為本機數據添加繪制代碼
// Clear out the color & depth buffers
::glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
RenderScene();//繪圖都放在這
// Tell OpenGL to flush its pipeline
::glFinish();
// Now Swap the buffers
::SwapBuffers( m_pDC->GetSafeHdc() );
}
10， 為了使改變窗口大小時嚴重的閃爍，在OnEraseBkgnd里做一些操作，避免windows自己的窗口刷新閃爍。
BOOL CfirstView::OnEraseBkgnd(CDC* pDC)
{
// TODO: 在此添加消息處理程序代碼和/或調用默認值
return TRUE;
}
11， 為了避免內存泄露，我們要將在SetupPixelFormat（）中使用了new運算符來為CClientDC對象分配的內存在程序關閉時delete掉。
void CfirstView::OnDestroy()
{
CView::OnDestroy();
// TODO: 在此處添加消息處理程序代碼
//Make the RC non-current
if(::wglMakeCurrent (0,0) == FALSE)
{
MessageBox(_T("Could not make RC non-current"));
}
//Delete the rendering context
if(::wglDeleteContext (m_hRC)==FALSE)
{
MessageBox(_T("Could not delete RC"));
}
//Delete the DC
if(m_pDC)
{
delete m_pDC;
}
//Set it to NULL
m_pDC = NULL;
}
12， 下面寫主繪圖函數，RenderScene(),在窗口畫了一個正方體、一個四面體。
void CfirstView::RenderScene()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glLoadIdentity(); // Reset The Current Modelview Matrix
glTranslatef(-1.5f,0.0f,-6.0f); // Move Left 1.5 Units And Into The Screen 6.0
glRotatef(30,0.0f,1.0f,0.0f); // Rotate The Triangle On The Y axis ( NEW )
glBegin(GL_TRIANGLES); // Start Drawing A Triangle
glColor3f(1.0f,0.0f,0.0f); // Red
glVertex3f( 0.0f, 1.0f, 0.0f); // Top Of Triangle (Front)
glColor3f(0.0f,1.0f,0.0f); // Green
glVertex3f(-1.0f,-1.0f, 1.0f); // Left Of Triangle (Front)
glColor3f(0.0f,0.0f,1.0f); // Blue
glVertex3f( 1.0f,-1.0f, 1.0f); // Right Of Triangle (Front)
glColor3f(1.0f,0.0f,0.0f); // Red
glVertex3f( 0.0f, 1.0f, 0.0f); // Top Of Triangle (Right)
glColor3f(0.0f,0.0f,1.0f); // Blue
glVertex3f( 1.0f,-1.0f, 1.0f); // Left Of Triangle (Right)
glColor3f(0.0f,1.0f,0.0f); // Green
glVertex3f( 1.0f,-1.0f, -1.0f); // Right Of Triangle (Right)
glColor3f(1.0f,0.0f,0.0f); // Red
glVertex3f( 0.0f, 1.0f, 0.0f); // Top Of Triangle (Back)
glColor3f(0.0f,1.0f,0.0f); // Green
glVertex3f( 1.0f,-1.0f, -1.0f); // Left Of Triangle (Back)
glColor3f(0.0f,0.0f,1.0f); // Blue
glVertex3f(-1.0f,-1.0f, -1.0f); // Right Of Triangle (Back)
glColor3f(1.0f,0.0f,0.0f); // Red
glVertex3f( 0.0f, 1.0f, 0.0f); // Top Of Triangle (Left)
glColor3f(0.0f,0.0f,1.0f); // Blue
glVertex3f(-1.0f,-1.0f,-1.0f); // Left Of Triangle (Left)
glColor3f(0.0f,1.0f,0.0f); // Green
glVertex3f(-1.0f,-1.0f, 1.0f); // Right Of Triangle (Left)
glEnd(); // Done Drawing The Pyramid
glLoadIdentity(); // Reset The Current Modelview Matrix
glTranslatef(1.5f,0.0f,-7.0f); // Move Right 1.5 Units And Into The Screen 7.0
glRotatef(25,1.0f,1.0f,1.0f); // Rotate The Quad On The X axis ( NEW )
glBegin(GL_QUADS); // Draw A Quad
glColor3f(0.0f,1.0f,0.0f); // Set The Color To Green
glVertex3f( 1.0f, 1.0f,-1.0f); // Top Right Of The Quad (Top)
glVertex3f(-1.0f, 1.0f,-1.0f); // Top Left Of The Quad (Top)
glVertex3f(-1.0f, 1.0f, 1.0f); // Bottom Left Of The Quad (Top)
glVertex3f( 1.0f, 1.0f, 1.0f); // Bottom Right Of The Quad (Top)
glColor3f(1.0f,0.5f,0.0f); // Set The Color To Orange
glVertex3f( 1.0f,-1.0f, 1.0f); // Top Right Of The Quad (Bottom)
glVertex3f(-1.0f,-1.0f, 1.0f); // Top Left Of The Quad (Bottom)
glVertex3f(-1.0f,-1.0f,-1.0f); // Bottom Left Of The Quad (Bottom)
glVertex3f( 1.0f,-1.0f,-1.0f); // Bottom Right Of The Quad (Bottom)
glColor3f(1.0f,0.0f,0.0f); // Set The Color To Red
glVertex3f( 1.0f, 1.0f, 1.0f); // Top Right Of The Quad (Front)
glVertex3f(-1.0f, 1.0f, 1.0f); // Top Left Of The Quad (Front)
glVertex3f(-1.0f,-1.0f, 1.0f); // Bottom Left Of The Quad (Front)
glVertex3f( 1.0f,-1.0f, 1.0f); // Bottom Right Of The Quad (Front)
glColor3f(1.0f,1.0f,0.0f); // Set The Color To Yellow
glVertex3f( 1.0f,-1.0f,-1.0f); // Top Right Of The Quad (Back)
glVertex3f(-1.0f,-1.0f,-1.0f); // Top Left Of The Quad (Back)
glVertex3f(-1.0f, 1.0f,-1.0f); // Bottom Left Of The Quad (Back)
glVertex3f( 1.0f, 1.0f,-1.0f); // Bottom Right Of The Quad (Back)
glColor3f(0.0f,0.0f,1.0f); // Set The Color To Blue
glVertex3f(-1.0f, 1.0f, 1.0f); // Top Right Of The Quad (Left)
glVertex3f(-1.0f, 1.0f,-1.0f); // Top Left Of The Quad (Left)
glVertex3f(-1.0f,-1.0f,-1.0f); // Bottom Left Of The Quad (Left)
glVertex3f(-1.0f,-1.0f, 1.0f); // Bottom Right Of The Quad (Left)
glColor3f(1.0f,0.0f,1.0f); // Set The Color To Violet
glVertex3f( 1.0f, 1.0f,-1.0f); // Top Right Of The Quad (Right)
glVertex3f( 1.0f, 1.0f, 1.0f); // Top Left Of The Quad (Right)
glVertex3f( 1.0f,-1.0f, 1.0f); // Bottom Left Of The Quad (Right)
glVertex3f( 1.0f,-1.0f,-1.0f); // Bottom Right Of The Quad (Right)
glEnd(); // Done Drawing The Quad
}