要求用户不干涉的情况下让物体自由旋转，这如果用win32的sdk直接来实现的话，就像Nehe的教程上那样是比较容易做的，可以在空闲事件的情况下调用绘图部分代码；
if (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) // Is There A Message Waiting?
{
TranslateMessage(&msg); // Translate The Message
DispatchMessage(&msg); // Dispatch The Message
}
else // If There Are No Messages
{
DrawGLScene()；
}
但MFC中我不了解到底该怎么弄才好，起先也是想放到空闲事件处理程序中去调用绘图代码，就写了如下代码：
BOOL COpenGLDemoApp::OnIdle(LONG lCount)
{
// TODO: Add your specialized code here and/or call the base class
CFrameWnd* pw=(CFrameWnd*)AfxGetMainWnd();
((COpenGLDemoView*)pw->GetActiveView())->DrawGLScene();
return CWinApp::OnIdle(lCount);
}
可发现效果不对劲，必须要用户的鼠标在上面滑动才会旋转，和要求完全不符合呀。于是我就换了个想法，试着用了一个定时器，让它定时刷新重绘，从而产生出旋转的效果，代码如下:
int COpenGLDemoView::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
if (CView::OnCreate(lpCreateStruct) == -1)
return -1;
// TODO: Add your specialized creation code here
HWND hWnd = this->GetSafeHwnd();
HDC hDC = ::GetDC(hWnd);
if(this->SetWindowPixelFormat(hDC)==FALSE)
{//设置像素格式
return 0;
}
if(this->CreateViewGLContext(hDC)==FALSE)
{//创建RC并选为所用
return 0;
}
if(!this->InitGL())
{//初始化openGL
return 0;
}
this->SetTimer(1,10,NULL);
return 0;
}
void COpenGLDemoView::OnPaint()
{
CPaintDC dc(this); // device context for painting
this->DrawGLScene();
}
void COpenGLDemoView::OnTimer(UINT nIDEvent)
{
// TODO: Add your message handler code here and/or call default
//控制旋转角度
rTri+=1.2f;
if(rTri>=360.0f)
{
rTri-=360.0f;
}
rQuads-=1.15f;
if(rQuads<=-360.0f)
{
rQuads+=360.0f;
}
InvalidateRect(NULL,FALSE);//角度更新了，通知其重绘
CView::OnTimer(nIDEvent);
}
int COpenGLDemoView::DrawGLScene()
{// Here's Where We Do All The Drawing
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear Screen And Depth Buffer
glShadeModel(GL_SMOOTH);
glLoadIdentity(); // Reset The Current Modelview Matrix
glTranslatef(-1.5f,0.0f,-6.0f);//物体左移1.5,向内移6,相当于移动镜头一样，让物体进入镜头中
glRotatef(rTri,0.0f,1.0f,0.0f);
glBegin(GL_TRIANGLES); // 绘制三角形
glColor3f(1.0f,0.0f,0.0f);
glVertex3f( 0.0f, 1.0f, 0.0f); // 上顶点
glColor3f(0.0f,1.0f,0.0f);
glVertex3f(-1.0f,-1.0f, 0.0f); // 左下
glColor3f(0.0f,0.0f,1.0f);
glVertex3f( 1.0f,-1.0f, 0.0f); // 右下
glEnd(); // 三角形绘制结束
glShadeModel(GL_FLAT);
glLoadIdentity();
glTranslatef(1.5f,0.0f,-6.0f);
glRotatef(rQuads,1.0f,0.0f,0.0f);
glBegin(GL_QUADS); // 绘制正方形
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(-1.0f, 1.0f, 0.0f); // 左上
glColor3f(1.0,1.0f,1.0f);
glVertex3f(-1.0f,-1.0f, 0.0f); // 右下
glColor3f(0.0f,0.0f,1.0f);
glVertex3f( 1.0f,-1.0f, 0.0f); // 左下
glColor3f(0.0f,1.0f,0.0f);
glVertex3f( 1.0f, 1.0f, 0.0f); // 右上
glEnd(); // 正方形绘制结束
glFlush();
rTri+=1.2f;
if(rTri>=360.0f)
{
rTri-=360.0f;
}
rQuads-=1.15f;
if(rQuads<=-360.0f)
{
rQuads+=360.0f;
}
HWND hWnd = this->GetSafeHwnd();
HDC hDC = ::GetDC(hWnd);
SwapBuffers(hDC);
return TRUE; // Everything Went OK
}
这下旋转的效果是有的，但由于是强制其重绘，所以画面刷新不过来，即使我用了双缓冲，画面还是闪烁得很。这个问题困惑了我一晚上，到底应该怎么弄呢？
本文转自Phinecos(洞庭散人)博客园博客，原文链接：http://www.cnblogs.com/phinecos/archive/2007/07/29/835632.html，如需转载请自行联系原作者
