On Friday 25 February 2005 12:54, Stephan Kulow wrote: > Am Friday 25 February 2005 18:03 schrieb Dieter Nützel: > > Am Freitag, 25. Februar 2005 16:47 schrieb Adam Jackson: > > > On Thursday 24 February 2005 13:27, Marcello Maggioni wrote: > > > > With XSCREENSAVER alone it effectively runs without problems , but I > > > > wonder why ... > > > > > > > > There's a logical explanation for this?? O_o > > > > > > Yeah. KDE's screensaver module probably opens its own fullscreen > > > window and tells the screensaver to draw on that. Since the window is > > > already created the screensaver can't change its visual, which means if > > > the window was created in a single buffer visual you're stuck. > > > > So someone should send a bug report to fix that before KDE 3.4 > > arise...;-) > > How? We create a fullscreen window for all screen savers.
Run glxinfo and look at the output near the bottom:
visual x bf lv rg d st colorbuffer ax dp st accumbuffer ms cav
id dep cl sp sz l ci b ro r g b a bf th cl r g b a ns b eat
----------------------------------------------------------------------
0x23 24 tc 0 24 0 r y . 8 8 8 0 0 0 0 0 0 0 0 0 0 None
0x24 24 tc 0 24 0 r . . 8 8 8 0 0 0 0 0 0 0 0 0 0 None
0x25 24 tc 0 24 0 r y . 8 8 8 0 0 24 8 0 0 0 0 0 0 None
0x26 24 tc 0 24 0 r . . 8 8 8 0 0 24 8 0 0 0 0 0 0 None
0x27 24 tc 0 24 0 r y . 8 8 8 0 0 0 0 16 16 16 0 0 0 Slow
0x28 24 tc 0 24 0 r . . 8 8 8 0 0 0 0 16 16 16 0 0 0 Slow
0x29 24 tc 0 24 0 r y . 8 8 8 0 0 24 8 16 16 16 0 0 0 Slow
0x2a 24 tc 0 24 0 r . . 8 8 8 0 0 24 8 16 16 16 0 0 0 Slow
Note the 'db' column, indicating a double-buffered visual. By default X
windows are not created in double-buffered visuals. The way to find a
double-buffered visual is something like:
int attribs[] = { GLX_DOUBLEBUFFER, /* ..., */ None };
XVisualInfo *vis = glXChooseVisual(dpy, DefaultScreen(dpy), attribs);
There's also a way to do this within the DBE extension, which one or two of
the xscreensaver hacks want, but I don't know it offhand. I expect Qt has an
idiom for this as well.
- ajax
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