| Disappearing Object Graphics... [message #29506] |
Sat, 23 February 2002 18:00 |
Ted Cary
Messages: 53
Registered: October 2001
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Member |
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Hello again,
I Googl-ed all the old postings about disappearing object graphics, and
after spending the last few days trying out the suggestions I still
haven't found a solution. I'm using object graphics in 2D. The graphics
tree is very simple: an IDLgrImage and several IDLgrROIGroups all in the
same model, the only model in the hierarchy (see picture at bottom).
The problem is that the ROIs disappear from the screen occasionally.
Changing the data or color of one ROI will completely erase another one,
although when I interrogate the hierarchy the erased ROI is still
there. All the ROIs are always exactly where they are supposed to be on
the tree, they all have valid drawable data, and they are all set to
draw in a visible color--so why do some of them not appear when I invoke
the window's draw method? Why does changing the color of an ROI and
then redrawing erase another ROI from the screen, although not from the
hierarchy? If I look at an ROI before and after it disappears, none of
its properties have changed and it still occupies the same position in
the hierarchy, so why doesn't it draw? Is there some problem with
calling SetProperty to set the data in atomic graphics objects in an
order other than the order with which they were originally added to the
model?
The ROIs are definitely not being hidden by the image, since when I
remove it from the tree and then redraw the same ROIs are still not
showing up. 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? I know I'm not the first who's had to resort to it,
since I got the idea from one of David Fanning's old responses. If
the Add/Draw order is correct, shouldn't IDL be able to draw all the
polygons on the plane?
Just for kicks, I've also tried every combination of RETAIN and
RENDERER, although for some reason (see earlier posting) when I
initialize RETAIN to 0 and then use GetProperty on my window it always
returns a RETAIN of 1,2, or most often 4 (?), which is completely
baffling me.
Anyway, here's my dying tree, with the IDLgrROIGroup branches stripped
of the IDLgrROIs that keep falling off:
View
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Model
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____________________________________________ _ _ _ _ _ _
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Image ROIGroup
ROIGroup ROIGroup...
Thanks for any help.
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