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Re: How to control the order of the objects to draw [using object graphics] [message #64905]

Wed, 28 January 2009 13:09

Mark[1]
Messages: 66
Registered: February 2008

Member

By default, the Object Graphics system controls visibility of
overlapping objects according to the position in the Z direction. So
if you want object A drawn in front of object B, put A above B
(greater Z).

It's a bit more complicated for IDLgrVolumes--for more info, search
this group for the word "pimento".

There are are a few object properties that modify this behaviour. The
effect of depth can be modfied by changing an IDLgrModel's
DEPTH_TEST_FUNCTION property. The effect of depth can be disabled by
setting an IDLgrModel's DEPTH_WRITE_DISABLE to 1; in this case the
visibility of objects in that model is controlled by position in the
container. Line-type atoms can be made to appear in front of filled
atoms at the same using the DEPTH_OFFSET function.

However I suggest you start by leaving the depth-cuing properties at
their default values and using depth (Z position) to control
visibility.

Mark

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Re: How to control the order of the objects to draw [using object graphics] [message #64912 is a reply to message #64905]

Tue, 27 January 2009 12:13

natha
Messages: 482
Registered: October 2007

Senior Member

Thank you David,

I didn't remember that the IDLgrModel is a container object and I
never used the IDLContainer::Move method before.

I think it will solve my problem.

Thanks,

Bernat

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Re: How to control the order of the objects to draw [using object graphics] [message #64913 is a reply to message #64912]

Tue, 27 January 2009 12:04

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

bernat writes:

> I 'm using object graphics in my application and sometimes one object
> hides the others because he's more big and it's drawed on the
> frontground.
> I don't know if it's possible to modify the order of the objects to
> draw.
>
> I really want to know how to do that !

I don't know this for a fact, although I would bet pretty big
on it, but I imagine that the order of drawing depends on
the order in which objects were added to the model (an
IDL_Container). Check the IDL_Container object documentation
for methods and keywords to change the order of objects
residing there.

Cheers,

David
--
David Fanning, Ph.D.
Coyote's Guide to IDL Programming (www.dfanning.com)
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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