actually, I might have to disagree now...I did a quick test using
SimpleUniverse which
is supposed to put your eye at 2.41 m from the center. I then put an object
at 0,0,0 with
a set of axes there as well. When I first start the view I am looking down
the Z axis (0,0,2.41)
towards the center (0,0,0) and see everything when I have a small
frontclipdistance.
But, when I set my front clip distance to 0.54 I see my object cut off, and
still see my axes.
When I go to 0.55 I no longer see my object and no longer see the axes...( I
did other tests
as well). My conclusion is then that the actual factor (you mention 7) is
closer to 4.38 (2.41/0.55)
which baffels me even more now. Note that for my other code I am using
VirtualUniverse so this
2.41 distance is removed from my view but I still see a wierd clipping
issue.
Thanks
Mario
-----Original Message-----
From: ZACZEK, MARIUSZ P. (MARIO) (JSC-DM) (NASA)
Sent: Friday, June 06, 2003 6:48 PM
To: [EMAIL PROTECTED]
Subject: Re: [JAVA3D] ? Clipdistance ratio = 3000 ... please explain ?
how did you find out you have to multiply by 7? And how do you know this is
correct?
I just did a quick demo using SimpleUniverse (other code I use
VirtualUniverse) and
you are correct...this is really wierd. Is it documented anywhere on the
javadocs and
I just missed it? (or, I did not look hard enough :) )
thanks,
.... now if someone can only help me with the ratio question ;)
Mario
Mariusz Zaczek
NASA - Johnson Space Center
Automated Vehicles and Orbit Analysis / DM35
Flight Design and Dynamics Division
Mission Operations Directorate
Bldg: 30A Room: 3040A
Disclaimer: "The opinions, observations and comments expressed in my email
are strictly my own and do not necessarily reflect those of
NASA."
-----Original Message-----
From: John Wright [mailto:[EMAIL PROTECTED]
Sent: Friday, June 06, 2003 6:40 PM
To: [EMAIL PROTECTED]
Subject: Re: [JAVA3D] ? Clipdistance ratio = 3000 ... please explain ?
Multiply your clip values by 7 to get the actual distances the clipping
occurs at. I've got this documented on my website page of notes (as
I've posted to the list before).
- John Wright
Starfire Research
"ZACZEK, MARIUSZ P. (MARIO) (JSC-DM) (NASA)" wrote:
>
> Also,
> What exactly is the front clip plane distance? This may sound like a
> stupid question, but I am seeing clipping of objects before I even reach
> this distance. I tested with a front clip distance of 0.05 but before I
> even go 0.2 away from the object, the object got clipped. And YES, the
> object
> is at 0,0,0 (well, actually, it's at another point but I use
OrbitBehavior
> to set my rotation center on this object...and NO, this is not the cause
> of the
> clip because the actual object is far away from the ORIGINAL center
point
> so that
> rbitBehavior's setRotationCenter() function would probably show clipping
> at even
> greater distance if this was the problem.)
>
> SO, I am trying to understand this clipping better and if you have
> comments please
> let me know.
>
> Thanks,
> Mario
>
> -----Original Message-----
> From: ZACZEK, MARIUSZ P. (MARIO) (JSC-DM) (NASA)
> Sent: Friday, June 06, 2003 4:25 PM
> To: [EMAIL PROTECTED]
> Subject: [JAVA3D] ? Clipdistance ratio = 3000 ... please explain ?
>
> Hi,
> My question has to do with the Back-to-Front clip plane distance ratio
> which is
> recommened as being 3000 (although it can be more but with degredation).
>
> Take the case of a Solar System simulation where we have an Earth centered
> system
> containing an orbiting vehicle and the Moon.
>
> Earth Radius = ~ 6,400,000 m
> Vehicle altitude above earth = ~ 400,000 m
> Moon, Distance to Earth = ~ 380,000,000 m
>
> Say I have a vehicle which is orbiting around the earth and I am using a
> camera to
> follow this vehicle. Say the altitude is 400,000 m (400km...low earth
> orbit)
> ...IF I want to be able to have a 1 m resolution (1 m front clip distance)
> and still
> be able to see the earth below then I have to have a back clip distance of
> at least
> 400,000 ... which means the ratio is 400,000!!!!! This is 100+ times what
> the recommended
> ratio of 3000.
>
> Even worse, if I am following this vehicle as it orbits the moon and want
to
> keep the
> 1 m distance from the vehicle and still see the earth (maybe see an Earth
> Rise) then the ratio
> is 380,000,000 to 1 .... WAY ABOVE the 3000 recommended.
>
> SO, my problem is that I want to be able to have the ability to zoom close
> to a vehicle
> and still be able to see earth below it....and more importantly be able to
> see other vehicles
> that are going to rendezvous with mine but are far away...more than 3000 m
> away.
>
> For the most part, going higher than 3000 is ok for some things, but in
> other cases that
> I've come across, if I go above a ratio of 50,000 I get merging of
> geometries...ie, I see
> things behind the earth that should not be visible.
>
> Please give me suggestions to overcome this problem? ... should I be using
a
> different
> "policy" for the back/front clip planes? Oh, and, explain it to me as if I
> was a 3 year old
> so I can easily implement it.
>
> Thank you for your help,
>
> Mario
>
> Mariusz Zaczek
> NASA - Johnson Space Center
> Automated Vehicles and Orbit Analysis / DM35
> Flight Design and Dynamics Division
> Mission Operations Directorate
> Bldg: 30A Room: 3040A
>
> Disclaimer: "The opinions, observations and comments expressed in my email
> are strictly my own and do not necessarily reflect those of
> NASA."
>
>
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