Re: XForms: xyplot limit

Steve Lamont (spl@szechuan.ucsd.edu)
Thu, 23 Jul 98 13:14:00 PDT

# To subscribers of the xforms list from spl@szechuan.ucsd.edu (Steve Lamont) :

TC sez:
> I think the problem might not be the limitation on the number of
> points. Rather, the limit is on the xy values. If I remember
> correctly (I am at siggraph, and can't look it up), the points are
> represented by unsigned shorts. If your plots are somewhat linearly
> scaled, by point number 64k, x or y will wrap around and xforms
> clips these points.

I'm not sure why that would make a difference.

I presume you're referring to the XPoint structure

typedef struct {
short x, y;
} XPoint;

which, of course, is limited to the precision of an signed short
(which should be -32768 to 32767). As far as I can see, this
basically says that your display may be no larger than 32767 x 32767
pixels since XPoint directly maps into a frame buffer pixel address as
far as I am able to tell.

The number of *distinct* points therefore will be limited by the pixel
resolution.

spl

_________________________________________________
To unsubscribe, send the message "unsubscribe" to
xforms-request@bob.usuf2.usuhs.mil or see
http://bob.usuf2.usuhs.mil/mailserv/xforms.html
XForms Home Page: http://bragg.phys.uwm.edu/xforms
List Archive: http://bob.usuf2.usuhs.mil/mailserv/list-archives/