《基于MFC的OpenGL编程》Part 5 Keyboard and Mouse Control

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

原文链接

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CMy2OpenGLView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CMy2OpenGLView.h中加入下列用于控制旋转和移动的变量：

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

并在构造函数中初始化：

CMy2OpenGLView::CMy2OpenGLView()
{
    // TODO: add construction code here
    m_xPos = 0.0f;
    m_yPos = 0.0f;
    m_xAngle = 0.0f;
    m_yAngle = 0.0f;

    m_bPoint    = FALSE;
    m_bLine        = FALSE;
    m_bPolygon    = FALSE;
    m_bTriangle = FALSE;
    m_bCube           = FALSE;        
    m_bTorus       = FALSE;        
    m_bTeapot       = FALSE;        
    m_bIcosahedron = FALSE;
    m_bSimpleCube  = FALSE;  
}

3、加入绘制一个立方体的代码（上一篇的太阳月亮行星暂时注释掉）：

void CMy2OpenGLView::RenderSceneSun()
{
	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);

// 	//Draw the sun 
// 	glLoadIdentity();
// 	glTranslatef(0.0f,0.0f,-5.0f);
// 	glRotatef(6.0f,1.0f,0.0f,0.0f);
// 	glutWireSphere(1.0f,20,20);
// 		//Draw the Planet
// 		glPushMatrix();
// 			glTranslatef(-1.2f,-0.5f,-2.0f);
// 			glRotatef(6.0f,1.0f,0.0f,0.0f);
// 			glutWireSphere(0.5f,20,20);
// 		//Draw the moon
// 		glPushMatrix();
// 			glTranslatef(-1.2f,-0.5f,-2.0f);
// 			glRotatef(6.0f,1.0f,0.0f,0.0f);
// 			glutWireSphere(0.05f,20,20);
// 		glPopMatrix();
// 		glPopMatrix();
}

4、为四个事件处理函数加入控制代码:

void CMy2OpenGLView::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+=0.1f;
		break;
	case VK_DOWN:	 m_yPos-=0.1f;
		break;
	case VK_LEFT:	 m_xPos-=0.1f;
		break;
	case VK_RIGHT:	 m_xPos+=0.1f;
		break;
	default: MessageBox("Press the arrow keys only!");
		break;
	}
	InvalidateRect(NULL,FALSE);

	CView::OnKeyDown(nChar, nRepCnt, nFlags);
}

void CMy2OpenGLView::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 CMy2OpenGLView::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 CMy2OpenGLView::OnMouseMove(UINT nFlags, CPoint point) 
{
	// TODO: Add your message handler code here and/or call default
	if (GetCapture()==this)
	{
		//Increase 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);
}

运行效果图：由于下段代码（在OnKeyDown（）方法中）截图时候老是弹屏，我就把他注释了。

default: MessageBox("Press the arrow keys only!");
		break;

附：以上是对一个立方体的操作，对于上篇博文中的太阳行星旋转同样适用，修改RenderSceneSun(),现在贴出代码：

注意：有个细节地方，

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);

标黑处：glRotatef(m_xAngles,1.0f,0.0f,0.0f);

glRotatef(m_yAngles,0.0f,1.0f,0.0f);

<span style="font-size:14px;">void CMy2OpenGLView::RenderSceneSun()
{
// 	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);

	//Draw the sun 
	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);
	glutWireSphere(1.0f,20,20);
		//Draw the Planet
		glPushMatrix();
			glTranslatef(m_xPos, m_yPos,-2.0f);
			glRotatef(m_xAngle,1.0f,0.0f,0.0f);
			glRotatef(m_yAngle,0.0f,1.0f,0.0f);
			glutWireSphere(0.5f,20,20);
		//Draw the moon
		glPushMatrix();
			glTranslatef(m_xPos, m_yPos,-2.0f);
			glRotatef(m_xAngle,1.0f,0.0f,0.0f);
			glRotatef(m_yAngle,0.0f,1.0f,0.0f);
			glutWireSphere(0.05f,20,20);
		glPopMatrix();
		glPopMatrix();
}</span>

代码运行结果：