UNTITLED LOCAL UNTITLED
NAMEglutInit — Initialize OpenGLUT data structures.
LIBRARY
OpenGLUT - mainloop
SYNOPSIS
#include <openglut.h>
void
glutInit(int *pargc, char **argv);
PARAMETERS
pargc Pointer to something like main()'s argc.
argv Something like main()'s argv.
DESCRIPTION
This function should be called once, near the start of any GLUT, freeg‐
lut, or OpenGLUT program. It serves two vital roles:
- It allows OpenGLUT to initialize internal structures.
- It allows OpenGLUT to process command-line arguments to control the
initial window position, etc.
You should take note of the interaction between glutInit() and the
related functions such as glutInitWindowPosition(). OpenGLUT always uses
the most recent configuration information, so if you call glutInit(),
then glutInitWindowPosition(), you prevent the user from controlling the
initial window position via a command-line parameter.
glutInit() will remove from pargc, argv any parameters that it recog‐
nizes in the command line. The following command-line parameters are
suported:
- -display display-id This allows connection to an alternate X
server.
- -geometry geometry-spec This takes width, height, and window posi‐
tion. The position is given as a signed value (negative values being
distance from the far boundary of the screen). For example, a window
geometry of 5x7+11-17 is 5 pixels wide, 7 pixels tall, 11 pixels from the
left, and 17 pixels from the bottom edge of the screen.
- -direct Insist on only OpenGL direct rendering. Direct rendering is
normally requested but indirect is normally accepted. -direct is not
always available. See -indirect.
- -indirect Attempt only indirect OpenGL rendering. -indirect is
always available. See -direct.
- -iconic Open the window in iconized form.
- -gldebug Print any detected OpenGL errors via glutReportErrors().
Presently done at the bottom of glutMainLoopEvent().
- -sync Synchronize the window system communications heavily.
Additionally, this function checks whether the environment variable
GLUT_FPS is defined (only on UNIX_X11); if so, OpenGLUT will periodi‐
cally print the average number of times per second that your program
calls glutSwapBuffers().
CAVEATS
You really should always call this, even if you are a WIN32 user. It
provides a way for the user to directly inform OpenGLUT about preferences
without the application needing to explicitly deal with those issues.
This is also where OpenGLUT retrieves your program's name to help disam‐
biguate error and warning messages it may be forced to emit.
Option -sync sets a flag, but is not actually used at this time.
Lots of code does XFlush() on the X server, regardless of whether -sync
is specified. Much of that appears to be required in order to support
direct client invocation of glutMainLoopEvent(), regrettably. However,
if one calls glutMainLoop(), instead, we might avoid gratuitous XFlush()
calls. (That last sentence isn't particularly germain to this function,
but there's no better place to make this remark at this time.) Even for
glutMainLoopEvent(), we may be able to coalesce many XFlush() calls.
SEE ALSOglutInitWindowPosition(3)glutInitWindowSize(3)glutInitDisplayMode(3)glutInitDisplayString(3)glutCreateWindow(3)glutDisplayFunc(3)glutMainLoop(3)glutMainLoopEvent(3)glutReportErrors(3)glutSwapBuffers(3)
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