Thanks very much. Back clipping now works just fine!
Bob Gray
-----Original Message-----
From: Kevin Rushforth [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, August 24, 1999 11:14 AM
To: [EMAIL PROTECTED]
Subject: Re: [JAVA3D] SimpleUniverse View Clipping
The reason for the difference is that the values are in two different
coordinate systems. The view platform transform defines a
tranformation into ViewPlatform coordinates. With a policy of
PHYSICAL_EYE, the clip distance is specified in physical units (meters)
from the eye point. Using the default screen scale policy of
SCALE_SCREEN_SIZE, the scale factor of the transformation from
ViewPlatform coordinates to physical image plate coordinates is
physical_screen_width/2. The default physical_screen_width is 0.35
meters, making the scale of the VPC-to-image-plate transform 0.175.
Multiplying your translation of 5.0 by the scale factor of 0.175 equals
0.875, which is very close to the 0.88 you used. If you would prefer
to set the clip distance in virtual coordinates, then you can change
the back clip policy to VIRTUAL_EYE--the distance will be specified in
virtual world coordinates (which has the same scale as ViewPlatform
coordinates, absent a scale transform in the path from the Locale to
the ViewPlatform).
--
Kevin Rushforth
Java 3D Team
Sun Microsystems
[EMAIL PROTECTED]
>Date: Mon, 23 Aug 1999 12:55:52 -0400
>Reply-To: Discussion list for Java 3D API <[EMAIL PROTECTED]>
>From: Bob Gray <[EMAIL PROTECTED]>
>Subject: [JAVA3D] SimpleUniverse View Clipping
>To: [EMAIL PROTECTED]
>
>Well, with a little playing around and some help from Barry,
>I was able to get everything in the -z region to disapear.
>
>But I had to specify a BackClipDistance of 0.88f !!
>which I don't understand at all.
>
>Why, if I am setting the view platform to be at
>z = +5.0f is the -z region a distance of 0.88f away?
>Can someone explain this to me?
>
>Here is the code I am using to set up the view platform
>location and back clipping distance.
>
>
> vpTrans = SU.getViewingPlatform().getViewPlatformTransform();
> translate.set(0.0f, 0.0f, 5.0f);
> T3D.setTranslation(translate);
> vpTrans.setTransform(T3D);
>
> SU.getViewer().getView().setBackClipPolicy(View.PHYSICAL_EYE);
> SU.getViewer().getView().setBackClipDistance(0.88f);
>
>Any thoughts?
>
>Bob Gray
>
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