Lighthouse3d.com >> GLUT Tutorial >> Subwindows >> Reshape Subwindows
重整函数的回调需要处理两件事:修改子窗体的大小,重新计算投影每个子窗体的投影矩阵.在我们的情况中,我们不需要渲染任何几何图案到主窗体,所以我们可以跳过重新计算投影矩阵这一步.
先来介绍修改大小和重定位子窗体的函数原型.
void glutPositionWindow(int x, int y);
void glutReshapeWindow(int width, int height);
x, y - 窗体的左上角
width, heith - 窗体的像素维度
这里有两个函数可以作用到当前窗体,所以我们必须设置一个特殊的窗体来作为当前窗体.为了这个,我们要把窗体ID传入glutSetWindows.原型如下:
void glutSetWindow(int windowIdentifier);
windowIdentifier - 创建窗体的返回值
如果我们需要知道哪个窗体是当前窗体(获得焦点),我们可以用glutGetWindow函数.
int glutGetWindow();
该函数的返回值是当前窗体(获得焦点)的ID.
在定位和更改窗体大小之前,我们必须设置每个子窗体为当前窗体.下面代码提供了重整函数,用到changeSize函数.上一节说过,我们要定义一个回调来专门给主窗体重整窗体.这样已经足够了,因为用户默认只能更改主窗体.
在我们的示例中,投影和所有子窗体类似,我们将会定义一个函数来实现,并在每个子窗体调用它.
int w,h, border=;
... void setProjection(int w1, int h1)
{
float ratio;
// Prevent a divide by zero, when window is too short
// (you cant make a window of zero width).
ratio = 1.0f * w1 / h1;
// Reset the coordinate system before modifying
glMatrixMode(GL_PROJECTION);
glLoadIdentity(); // Set the viewport to be the entire window
glViewport(, , w1, h1); // Set the clipping volume
gluPerspective(,ratio,0.1,);
glMatrixMode(GL_MODELVIEW);
} void changeSize(int w1,int h1) { if(h1 == )
h1 = ; // we're keeping these values cause we'll need them latter
w = w1;
h = h1; // set subwindow 1 as the active window
glutSetWindow(subWindow1);
// resize and reposition the sub window
glutPositionWindow(border,border);
glutReshapeWindow(w-*border, h/ - border*/);
setProjection(w-*border, h/ - border*/); // set subwindow 2 as the active window
glutSetWindow(subWindow2);
// resize and reposition the sub window
glutPositionWindow(border,(h+border)/);
glutReshapeWindow(w/-border*/, h/ - border*/);
setProjection(w/-border*/,h/ - border*/); // set subwindow 3 as the active window
glutSetWindow(subWindow3);
// resize and reposition the sub window
glutPositionWindow((w+border)/,(h+border)/);
glutReshapeWindow(w/-border*/,h/ - border*/);
setProjection(w/-border*/,h/ - border*/);
}