glutsetwindow(3) - Linux man page

Name

glutSetWindow - Select the <i>current window</i>

Library

OpenGLUT - window

Synopsis

#include <openglut.h>

void

glutSetWindow(int ID);

Parameters

ID Window identifier

Description

Sets the current window to ID.

All OpenGL rendering goes to the current window . Many OpenGLUT functions also implicitly use the current window .

Many OpenGLUT callback operations are tied to a window. When your callback is invoked, OpenGLUT will set that particular window to be the current window . However, some callbacks---such as that registered via glutIdleFunc()---do not have associated windows. If a callback is not associated to a particular window, then when OpenGLUT invokes that callback you should always use glutSetWindow() to select the appropriate window before doing any OpenGL rendering or doing any OpenGLUT window-related operations.

There may be cases when you can get away with assuming that the current window is unchanged since some prior time, but OpenGLUT has considerable liberaty with respect to when it invokes your functions. Also, your program may add more windows or more operations on other windows as you develop it.

Lastly, this is a convenient way to select among multiple windows for drawing without actually waiting for that window's display callback. Simply set the current window and draw immediately. This is not always advisable, but may be practical.