[OpenGL] 2、企业版VC6.0自带的Win32-OpenGL工程浅析

[b]一、 建立工程[/b]

O(∩_∩)O~上一节介绍了一种非常容易的OpenGL的搭建方法，这一节将就上一节介绍的VC6.0企业版自带的OpenGL Win32 Application建立一个模板工程，并分析这个模板工程，便于今后我们在此基础上进行修改~



PS: 如果有报错，请仔细读上一节的介绍哦~好像Win8不行的！



二、 框架逻辑分析

O(∩_∩)O~工程建好之后主要的就是上图中用红框框起来的文件

2-1、 OpenGL1.cpp分析

其中OpenGL1.cpp就是Win32应用程序的主逻辑框架啦~由下面OpenGL1.h中主要代码可以看出该文件和Win32原框架很像，主要由初始化窗口、消息回调、退出等组成：

①InitInstance负责产生并显示窗口；

②ExitInstance()什么都没有；

③OnCommand()消息回调，这里只有一个IDM_EXIT消息发送WM_CLOSE；

④WindowProc()窗口消息回调函数及相关窗口消息都在此处理；

剩下几个注释很明白~

/////////////////////////////////////////////////////////////////////////////
// CApp
// Application class

class CApp
{
protected:
HINSTANCE m_hInst;
CMainWnd* m_pMainWnd;

public:
CApp();
~CApp();

int Run();                // Starts the message pump
void OnIdle();            // Called when there are no messages in the message queue.
// Sets current OpenGL RC and notifies the main window class that another frame
// is to be drawn.
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow, LPSTR lpCmdLine);
// Called when the application starts. Creates and shows the main window.
void ExitInstance();      // Called when the application exits.
BOOL OnCommand(int nCmdID, int nEvent);// Handles WM_COMMAND messages
LRESULT WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
// Handles messages sent to the main window
void OnPaint(HDC hDC);    // Handles WM_PAINT messages. Redraws the OpenGL scene.
void OnDestroy();         // Called when the main window is destroyed. Shuts down OpenGL
void OnCreate();          // Called when the main window has been created. Initializes OpenGL.
void OnSize(int cx, int cy);// Called when the main window is resized. Resizes the OpenGL
};

2-2、 OpenGL1.cpp分析

其中OpenGL1.cpp就是来处理OpenGL的相关东西，从下面的OpenGL1.h可以看出：

class CMainWnd
{
public:
CMainWnd();
virtual ~CMainWnd();

HWND m_hWnd;
HGLRC m_hRC;          // Handle to RC
GLfloat m_fAngle; // Rotation angle of the cube

void DrawScene();
void KillScene();
void InitScene();
void Tick(BOOL &bRedrawScene);
};

三、本例程细节

对于本模板带的绘制例子，这里大致分析下：

>_<" 首先看void CMainWnd::InitScene()函数主要是设置灯光和材质（现在先别管具体函数是啥，大致知道是这个就行）

//
// InitScene()
// Called when the OpenGL RC has been created. Sets the initial state for
// the OpenGL scene.
//
void CMainWnd::InitScene()
{
glClearColor(0.000f, 0.000f, 0.000f, 1.0f); //Background color

// TODO: Replace the following sample code with your initialization code.

// Activate lighting and a light source
glEnable(GL_LIGHT0);
glEnable(GL_LIGHTING);
glEnable(GL_DEPTH_TEST);

// Define material parameters
static GLfloat glfMatAmbient[] = {0.000f, 0.450f, 1.000f, 1.0f};
static GLfloat glfMatDiffuse[] = {0.000f, 0.000f, 0.580f, 1.0f};
static GLfloat glfMatSpecular[]= {1.000f, 1.000f, 1.000f, 1.0f};
static GLfloat glfMatEmission[]= {0.000f, 0.000f, 0.000f, 1.0f};
static GLfloat fShininess = 128.000f;

// Set material parameters
glMaterialfv(GL_FRONT, GL_AMBIENT,  glfMatAmbient);
glMaterialfv(GL_FRONT, GL_DIFFUSE,  glfMatDiffuse);
glMaterialfv(GL_FRONT, GL_SPECULAR, glfMatSpecular);
glMaterialfv(GL_FRONT, GL_EMISSION, glfMatEmission);
glMaterialf(GL_FRONT, GL_SHININESS, fShininess);
}

>_<" 其次要看CMainWnd::DrawScene()函数，这个函数在每个时间点被调用来绘制OpenGL3D图。这里主要清空缓存、加载光源、加载镜头、绘制正方体（这里正方体封装到GLCube(-r, -r, -r, r, r, r);函数中。

//
// DrawScene()
// Called each time the OpenGL scene has to be drawn.
//
void CMainWnd::DrawScene()
{
// TODO: Replace the following sample code with your code to draw the scene.

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear buffers
glLoadIdentity(); // Load identity matrix

// Add a light source
GLfloat glfLight[] = {-4.0f, 4.0f, 4.0f, 0.0f};
glLightfv(GL_LIGHT0, GL_POSITION, glfLight);

// Position and rotate the camera
glTranslatef(0.0f, 0.0f, -5.0f);
glRotatef(30.0f, 1.0f, 0.0f, 0.0f);
glRotatef(m_fAngle, 0.0f, 1.0f, 0.0f);

// Draw a cube
static GLfloat r = .7f;
GLCube(-r, -r, -r, r, r, r);

glFlush();
}

>_<" 下面是GLCuBe函数，用来绘制正方体的：由参数知道其输入正方体的左上角和右下角，然后根据这两个点按照顺序绘制正方体在三维空间中的6个面，这样就组成了一个空间中的正方形了。

//
// GLCube()
// Renders a cube.
//
void GLCube(GLfloat x1, GLfloat y1, GLfloat z1, GLfloat x2, GLfloat y2, GLfloat z2)
{
glBegin(GL_POLYGON);
glNormal3f(0.0f, 0.0f, 1.0f);
glVertex3f(x2, y2, z2);
glVertex3f(x1, y2, z2);
glVertex3f(x1, y1, z2);
glVertex3f(x2, y1, z2);
glEnd();

glBegin(GL_POLYGON);
glNormal3f(0.0f, 0.0f, -1.0f);
glVertex3f(x2, y2, z1);
glVertex3f(x2, y1, z1);
glVertex3f(x1, y1, z1);
glVertex3f(x1, y2, z1);
glEnd();

glBegin(GL_POLYGON);
glNormal3f(-1.0f, 0.0f, 0.0f);
glVertex3f(x1, y2, z2);
glVertex3f(x1, y2, z1);
glVertex3f(x1, y1, z1);
glVertex3f(x1, y1, z2);
glEnd();

glBegin(GL_POLYGON);
glNormal3f(1.0f, 0.0f, 0.0f);
glVertex3f(x2, y2, z2);
glVertex3f(x2, y1, z2);
glVertex3f(x2, y1, z1);
glVertex3f(x2, y2, z1);
glEnd();

glBegin(GL_POLYGON);
glNormal3f(0.0f, 1.0f, 0.0f);
glVertex3f(x1, y2, z1);
glVertex3f(x1, y2, z2);
glVertex3f(x2, y2, z2);
glVertex3f(x2, y2, z1);
glEnd();

glBegin(GL_POLYGON);
glNormal3f(0.0f, -1.0f, 0.0f);
glVertex3f(x1, y1, z1);
glVertex3f(x2, y1, z1);
glVertex3f(x2, y1, z2);
glVertex3f(x1, y1, z2);
glEnd();
}

四、效果及相关链接



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第一节OpenGL环境搭建：/article/5083853.html