1，glTranslatef(-1.5f,0.0f,-6.0f);这里是被观察的物体在移动，还是视点的位置移动呢
我的理解是后者（就好像是照相机在移动位置来捕捉画面那样），默认的物体位置是屏幕中心，向左移动视图并将视图推远以便被观察的物体能进入，试着调整Z坐标的值，可以看到Z越往里面去，物体就越小，越往外面来，物体越大，这和照相机调整焦距类似。
2.使用Flat coloring(单调着色)给几何对象涂上固定的一种颜色。使用Smoothcoloring(平滑着色)将几个顶点的不同颜色混合在一起，创建漂亮的色彩混合。要注意窗口调整大小以及被其他窗口挡住后重新激活时要重新设置Shade Model。
int COpenGLDemoView::DrawGLScene(GLvoid)
{// Here's Where We Do All The Drawing
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);//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
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);
glTranslatef(3.0f,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();
return TRUE; // Everything Went OK
}
void COpenGLDemoView::OnActivateView(BOOL bActivate, CView* pActivateView, CView* pDeactiveView)
{
// TODO: Add your specialized code here and/or call the base class
InitGL();//激活窗口时强制要求还原openGL状态
CView::OnActivateView(bActivate, pActivateView, pDeactiveView);
}
void COpenGLDemoView::OnSize(UINT nType, int cx, int cy)
{
CView::OnSize(nType, cx, cy);
// TODO: Add your message handler code here
GLsizei width,height;
width = cx;
height = cy;
if (height==0) // Prevent A Divide By Zero By
{
height=1; // Making Height Equal One
}
glShadeModel(GL_SMOOTH);
glViewport(0,0,width,height); // Reset The Current Viewport
glMatrixMode(GL_PROJECTION); // Select The Projection Matrix
glLoadIdentity(); // Reset The Projection Matrix
// Calculate The Aspect Ratio Of The Window
gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);//透视投影
glMatrixMode(GL_MODELVIEW); // Select The Modelview Matrix
glLoadIdentity(); // Reset The Modelview Matrix
}
BOOL COpenGLDemoView::InitGL(GLvoid) // All Setup For OpenGL Goes Here
{
glShadeModel(GL_SMOOTH); // Enable Smooth Shading
glClearColor(0.0,0.0,0.0,0.0);// Black Background
glClearDepth(1.0f); // Depth Buffer Setup
glEnable(GL_DEPTH_TEST); // Enables Depth Testing
glDepthFunc(GL_LEQUAL); // The Type Of Depth Testing To Do
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // Really Nice Perspective Calculations
return TRUE; // Initialization Went OK
}
3，如果是下面这样设置颜色，则请问正方形的颜色会是怎么样的呢？
glShadeModel(GL_FLAT);
glTranslatef(3.0f,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
呵呵，答案是：颜色会是绿色的，也就是说是以最后那个顶点的颜色为标准的，这是因为Flat coloring(单调着色)是会给四边形涂上固定的一种颜色，而最后一个顶点的颜色设置后，就覆盖了前面的颜色设置。
本文转自Phinecos(洞庭散人)博客园博客，原文链接：http://www.cnblogs.com/phinecos/archive/2007/07/29/835433.html，如需转载请自行联系原作者
