something wrong with your program.
-----Message d'origine-----
De : Emanuel Brzostowski <[EMAIL PROTECTED]>
� : [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date : samedi 16 novembre 2002 03:23
Objet : Re: [JAVA3D] no Sync when using Behavior processStimulus (some code


>Hi
>
>I see my argumentation was a bit short-sighted.
>The samplecode is in the attachment, hope this helps.
>
>> You might be able to use the Background node as a workaround
>Maybe for this case i used in my sample (Stars in the Background), but
there
>are other things in my application, which can't be done this way, so
leading
>me to the same problems.
>I already thought about using locales too, and i surely will have to use
>them, when i start to model bigger parts of the cosmos.
>
>- emanuel
>
>> > Date:         Fri, 15 Nov 2002 14:21:18 +0100
>> > From: Emanuel Brzostowski <[EMAIL PROTECTED]>
>> >
>> > > Moving both viewplatform and object by similar transform will degrade
>> > > quality. You should try to keep all objects as close to center as
>> > > possible - within 100000 units let say.
>> >
>> > Exatly this is the point! The only transform i apply is a transform to
>> the
>> > viewplatform:
>> >    viewTransform.mul(moveTrans);
>> >
>> > If we talk about precision, this is the only point, where precision may
>> play
>> > a role. The multiplication is only numeric, so errors will surely occur
>> and
>> > accumulate over time.  BUT after this, i do no more transformations, i
>> just
>> > take the translational part out of the viewtransform (-matrix) and
>> rebuild my
>> > objecttransform:
>> >   viewTransform.get(viewTranslation);
>> >   StarsTransform.setTranslation(viewTranslation);
>> >   StarsTransformGroup.setTransform(StarsTransform);
>> >   viewTransformGroup.setTransform(viewTransform);
>> >
>> > So in turn i should have two transforms with should be equal (at least
>> in the
>> > translational parts).  (In fact i tested it, objecttransform and
>> > viewtransform ARE equal the whole time in my testcase.)  So even if
>> java3d
>> > would use integers internally, after all the transforms are the same ;)
>>
>> Because this is a scenegraph, the view transform has to be inverted and
>> multiplied with the object transform to get the transform from object
>> coordinates to view platform coordinates (and from there to eye
>> coordinates and
>> projection/clipping coordinates).  But since the view and object
>> transforms are
>> just translations, Java 3D should recognize that all it needs to do is
>> subtract
>> the translation components.
>>
>> Bottom line, we can't tell from the code snippets and description you
>> provided
>> whether this a user error, a problem with scene graph update
>> synchronization, a
>> transform problem, or some inherent precision limitation.  Send us a
small
>> but
>> complete test application that reproduces the problem and we'll be able
to
>> investigate further.
>>
>> You might be able to use the Background node as a workaround -- it was
>> designed
>> to eliminate translation effects, rendering the Background geometry "at
>> infinity".  And as you noted, the problem is only with large distances,
so
>> you
>> might consider keeping your objects closer to the origin, or investigate
>> the
>> use of multiple Locales with different origins in high-resolution
>> coordinates.
>>
>> -- Mark Hood
>>
>>
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