[comp.sys.sgi] Drawing into the fullscreen

tjh@ouzo.bu.edu (Tim Hall) (01/15/90)

How is it possible to draw into the whole screen even though the
window you have opened is smaller than the whole screen?  I don't
care if I'm drawing over other windows.  (Actually I'm using 
overlays so it doesn't matter)  I tried screenspace( ) and that
didn't do it.  I tried the viewport/ortho2 that screenspace( )
is supposed to do and that didn't do it. In both cases when what
it is that I'm drawing is in my window it shows up, but never shows
up outside my window.

Thanks
-Tim Hall

"Severance, The birds of leaving call to us, yet here we stand
endowed with the fear of flight" -Dead Can Dance

tarolli@riva.esd.sgi.com (Gary Tarolli) (01/17/90)

In article <50523@bu.edu.bu.edu>, tjh@ouzo.bu.edu (Tim Hall) writes:
> How is it possible to draw into the whole screen even though the
> window you have opened is smaller than the whole screen?  I don't
> care if I'm drawing over other windows.  (Actually I'm using 
> overlays so it doesn't matter)  I tried screenspace( ) and that
> didn't do it.  I tried the viewport/ortho2 that screenspace( )
> is supposed to do and that didn't do it. In both cases when what
> it is that I'm drawing is in my window it shows up, but never shows
> up outside my window.
> 

Geez, you were so close, you almost got it - just delete 2 e's from fullscreen
and you get fullscrn().  Unfortunately the man page for screenspace() is
very misleading.  It does nothing but map world coordinates directly to pixels.
It does not allow you to do anything outside your window.  All drawing is
limited to the visible portions of your window through the use of window id
planes.  Fullscrn() disables window id checking and allows you access to the
entire screen.  Screenspace is typically used in conjuction with fullscrn()
to map world coords to pixels, however you are free to use whatever mapping
you want. 
--
						Gary Tarolli