《基于MFC的OpenGL编程》Part 6 Keyboard and Mouse Control

在上一篇的基础上加入对键盘和鼠标的事件处理程序，以便用其来控制 3D 物体的旋转和移动。

1,首先在CCY457OpenGLView类中为WM_KEYDOWN, WM_LBUTTONDOWN, WM_LBUTTONUP 和 WM_MOUSEMOVE四个事件加入事件处理函数。

2,在CCY457OpenGLView.h中加入下列用于控制旋转和移动的变量：并在构造函数中初始化：

     GLfloat m_xAngle;
     GLfloat m_yAngle;
     GLfloat m_xPos;
     GLfloat m_yPos;
     CPoint m_MouseDownPoint;

CCY457OpenGLView::CCY457OpenGLView()
{
     m_xPos = 0.0f ;
     m_yPos = 0.0f ;
     m_xAngle = 0.0f ;
     m_yAngle = 0.0f ;
}

3，加入绘制代码：

void COpenGLView::RenderScene ()
{
     glLoadIdentity();
     glTranslatef(m_xPos, m_yPos, -5.0f );
     glRotatef(m_xAngle, 1.0f,0.0f,0.0f );
     glRotatef(m_yAngle, 0.0f,1.0f,0.0f );

     glutWireCube(1.0f );
}

4，为四个事件处理函数加入控制代码

void COpenGLView::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
    // TODO: Add your message handler code here and/or call default
    switch (nChar)
     {
        case VK_UP:         m_yPos = m_yPos + 0.1f ;
                        break ;
        case VK_DOWN:     m_yPos = m_yPos - 0.1f ;
                        break ;
        case VK_LEFT:     m_xPos = m_xPos - 0.1f ;
                        break ;
        case VK_RIGHT:   m_xPos = m_xPos + 0.1f ;
                        break ;
        default:         MessageBox("Press the arrow keys only" );
                        break ;
     }        

     InvalidateRect(NULL,FALSE);
    
     CView::OnKeyDown(nChar, nRepCnt, nFlags);
}

void COpenGLView::OnLButtonDown(UINT nFlags, CPoint point)
{
    // TODO: Add your message handler code here and/or call default
     m_MouseDownPoint= point;
     SetCapture();
    
     CView::OnLButtonDown(nFlags, point);
}

void COpenGLView::OnLButtonUp(UINT nFlags, CPoint point)
{
    // TODO: Add your message handler code here and/or call default
     m_MouseDownPoint=CPoint(0,0 );
     ReleaseCapture();
    
     CView::OnLButtonUp(nFlags, point);
}

void COpenGLView::OnMouseMove(UINT nFlags, CPoint point)
{
    // TODO: Add your message handler code here and/or call default
    // Check if we have captured the mouse
    if (GetCapture()==this )
     {
        //Increment the object rotation angles
         m_xAngle+=(point.y-m_MouseDownPoint.y)/3.6 ;
         m_yAngle+=(point.x-m_MouseDownPoint.x)/3.6 ;
        //Redraw the view
         InvalidateRect(NULL,FALSE);
        //Set the mouse point
         m_MouseDownPoint= point;
     };
    
     CView::OnMouseMove(nFlags, point);
}