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Re: Disappearing Object Graphics... [message #29502 is a reply to message #29501]

Sun, 24 February 2002 15:14

Mark Hadfield
Messages: 783
Registered: May 1995

Senior Member

"Ted Cary" <tedcary@yahoo.com> wrote in message
news:3C78492A.B7F0D8E1@yahoo.com...

> ...I've tried increasing the z-coordinate of vertices to bring ROIs
> to the front, and this occasionally works, although just as often
> decreasing the z-coordinate to a negative value works instead.
> Eventually I usually can find an xy-plane on which an individual ROI
> is visible, but it's beginning to look like the only way to draw all
> the ROIs is to put each one on a different plane with a different
> z-coordinate, which seems ridiculous since I'm only working on one
> plane. Why is any of this z-coordinate manipulation ever necessary
> when working in 2D?

Because Object Graphics is deeply and intrinsically 3D.

It does seem you have some sort of vertical-overlap issue. But I don't
understand why IDLgrROI objects should obscure one another (except
when they have exactly the same coordinates) because they are
represented by polylines or points, not polygons.

This may be a bug.

By the way, the vertical separation required for reliable overlap
control with object graphics is approx. 2^-16 times the distance
between front and rear clipping planes. But it does vary with the
renderer.

> Just for kicks, I've also tried every combination of RETAIN and
> RENDERER

You did this for kicks? You are a sick boy.

---
Mark Hadfield
m.hadfield@niwa.co.nz http://katipo.niwa.co.nz/~hadfield
National Institute for Water and Atmospheric Research

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[Message index]

		Re: Disappearing Object Graphics... By: Ted Cary on Mon, 25 February 2002 10:41
		Re: Disappearing Object Graphics... By: Rick Towler on Mon, 25 February 2002 09:33
		Re: Disappearing Object Graphics... By: David Fanning on Sun, 24 February 2002 19:27
		Re: Disappearing Object Graphics... By: Mark Hadfield on Sun, 24 February 2002 15:14
		Re: Disappearing Object Graphics... By: Ted Cary on Sun, 24 February 2002 09:30
		Re: Disappearing Object Graphics... By: David Fanning on Sat, 23 February 2002 19:13

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