[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: IDLgrWindow (?) bug

Udo Grabowski (udo.grabowski@imk.fzk.de) writes:

> I myself experimented a couple of times with objects in direct graphics,
> and I immediately got rid of all problems when I realized that the
> viewplane_rect setting determines that data range of the plot which is projected
> INTO the viewport. The viewport itself is by default determined from the
> underlying 
> graphics window and may further be specified INSIDE the window by the 'location' 
> and 'dimensions' keywords in units given by the 'units' keyword (which has
> nothing 
> to do with the viewplane_rect entries). Keeping this in mind, all my plots since 
> then have an predictable and identical behaviour under direct as well as under 
> object graphics (except that color trouble...).

Here is a man who is *rapidly* gaining himself an invitation
to the next IEPA meeting. (I can't say where this is going to
be, but I can tell you it is in a VERY desirable location).
You are passing this information along to others, aren't you? :-)

You are right. The viewport is mapped into the graphics
window. It can be positioned in the window with the LOCATION
and DIMENSIONS keywords. The viewport rectangle (and the
associated Z clipping planes, which together create the
viewport volume) is described in whatever arbitrary 
coordinate system you like to make up! The only "trick"
to object graphics is learning how to put objects, which
are created in their "own" coordinate space, into the
arbitrary coordinate space of the viewport. Once you
understand this, everything else is just detail. :-)




David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155