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Aldo,
What you have done sounds promising, I don't know why you are getting
inconsistent results, I have not tried this myself.
I would also look at the:
Canvas3D.getVworldToImagePlate(Transform3D t)
method. By transforming two Vworld points separated by one meter
using the Transform3D from the method above you should be able to get
the distance in pixels directly without using picking.
Let me know how you get on!
Sincerely,
Daniel Selman
[EMAIL PROTECTED]
http://www.tornadolabs.com
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> -----Original Message-----
> From: Discussion list for Java 3D API
> [mailto:[EMAIL PROTECTED]]On Behalf Of Dipasqua, Aldo
> Sent: 14 February 2000 20:15
> To: [EMAIL PROTECTED]
> Subject: [JAVA3D] Canvas3D pixel size
>
>
> Hi Daniel,
>
> Would you please consider this:
>
> How does one compute the size of a Canvas3D pixel in meters that is
> currently being viewed (and compute it consistently)?
>
> I use the viewing platform to view a world globe (Sphere class)
> representing
> the earth. I have tried the following to do this with some success:
>
> * using two points in window (canvas) space, determine their
> j3d coordinates using picking technology (intersection with the
> sphere) * using the two j3d points compute the size of a
> pixel from that distance divided by the distance between the window
> points.
>
> This approach works when the Canvas3D is at its final state
> (after the swap
> ?). I used a behavior to detect a viewing platform change and then
> used that fact to do the computation. I have also tried computing
> the pixel size
> immediately after changing the viewing platform position. In both
> these cases, the result is not always correct unless I retry the
> computation one or more times (the Canvas3D is at it final state?).
>
> How does one know when the canvas is finished rendering (or the
> scenegraph completely traversed). I tried extending Canvas3D using
> my own postSwap or postRender methods, but this proved futile in
> resolving the problem above.
>
> Thanks in advance for shedding any light on this problem.
>
> Aldo Di Pasqua
>
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