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Re: Why are my 3D plots blue?

  • To: mathgroup at
  • Subject: [mg114360] Re: Why are my 3D plots blue?
  • From: John Fultz <jfultz at>
  • Date: Thu, 2 Dec 2010 05:38:49 -0500 (EST)

On Wed, 1 Dec 2010 02:10:11 -0500 (EST), Joseph Gwinn wrote:
> In article <id2eko$d5t$1 at>, John Fultz <jfultz at>
> wrote:
>> On Mon, 29 Nov 2010 06:07:39 -0500 (EST), Joseph Gwinn wrote:
>>> In article <ictfvj$mi6$1 at>, John Fultz
>>> <jfultz at>
>>> wrote:
>>>> If you can move the Dynamic inside of the Graphics3D[], you'll have
>>>> a
>>>> much
>>>> better experience.  I.e., instead of...
>>>> Dynamic[stuff; Graphics3D[{dirs}, opts]]
>>>> do this...
>>>> Graphics3D[Dynamic[stuff; {dirs}], opts]
>>> I will try this.
>>> Will something like:
>>> DynamicModule[{local variables},
>>> Dynamic[stuff];
>>> Graphics3D[ Dynamic[graphic directives], opts]
>>> ]
>>> also work?  I've tried some similar approaches, but the graphics didn't
>>> respond to mouse motion, don't know exactly why.  I would have thought
>>> that a local variable x would be linked by the Dynamic functions.  I
>>> assume I didn't quite do it right.
>> No, that won't work.  To understand why, read through my post here...
>> For a further library of stuff that I've written about Dynamic, see
>> here...
> Thanks.  I'll study these.  I've read all the relevant documentation,
> and still don't really have a complete grasp of Dynamic and its friends.
>>>> and if the options should be dynamically updated, put individual
>>>> Dynamics in the option values.
>>> Will this allow me to track the current value of for instance
>>> ViewMatrix?  I have tried Dynamic[ViewMatrix] to no effect, getting an
>>> unchanging empty list {} in response.
>> Alas, there's a bug here.  You're the first to uncover this, it appears.
>> I've made a report to the appropriate developers.
> Ahh.  Thanks. I would guess that you were already able to reproduce the
> problem, but here are some miscreants I tried:
> Graphics3D[{Text[Options[Dynamic[ViewMatrix]],{0,0,0}],Text[Options[Dynam
> ic[ViewPoint]],{0,0,1}]},ViewPoint->{Pi,Pi/2,2},SphericalRegion->True]
> Graphics3D[{Text[Dynamic[Options[ViewMatrix]],{0,0,0}],Text[Options[ViewP
> oint],{0,0,1}]},ViewPoint->{Pi,Pi/2,2},SphericalRegion->True]
> Dynamic[Graphics3D[{Text[Options[ViewMatrix],{0,0,0}],Text[Options[ViewPo
> int],{0,0,1}]},ViewPoint->{Pi,Pi/2,2},SphericalRegion->True]]
>>>> The basic problem here is that the Graphics3D is being recreated over
>>>> and over again and Mathematica is getting confused about what exactly
>>>> should be selected.  In typical examples, this kind of thing works
>>>> fine, but your code, for reasons I haven't investigated, stresses this
>>>> enough to expose the problem.  By preventing the Graphics3D wrapper
>>>> from being recreated, you can avoid the problem entirely.
>>> OK.  Sounds like it will be faster too.
>> Yes, but probably only marginally so.
> One thing I have been doing is to generate 3D plots in two pieces, with
> the unchanging background done once (with no Dynamic calls), the
> changing stuff generated in another Graphics3D, then using Show to merge
> things.  The pattern is something like:
> staticplot==Graphics3d[<background scenery>];  (* No Dynamic stuff *)
> DynamicModule[{local vars},
> dynamicplot==Graphics3D[Dynamic[<stuff that moves>]];
> Show[staticplot,dynamicplot]  ]
> Comments?  It this complication worthwhile?

Yes, this is good.  Alternatively, you could have also done...

Graphics3D[{<static stuff>, Dynamic[<dynamic stuff>]}]

>>> Another perhaps related effect discovered by accident is that moving
>>> the 3D mouse while Mathematica is doing the initial evaluation of the
>>> notebook can cause Mathematica to crash with a SEGFAULT error.  This
>>> happened a few days ago, and I allowed MacOS to send the crash report
>>> to Apple.
>> This might require further investigation of the specific notebook you're
>> working with.   I suggest starting a dialog with technical support
>> about this.
> OK.  If I can reproduce the problem.  I assume that Tech Support can
> access Mathematica crash logs sent to Apple.

Not a safe assumption.  I don't know as much about Apple's mechanism, but I know
that Microsoft prevents developers from being able to correlate crash reports
with specific users as a means of protecting privacy.  I'll bet Apple does
something similar.


John Fultz
jfultz at
User Interface Group
Wolfram Research, Inc.

> I bet the logs are under a
> rock somewhere on my machine somewhere as well.
> Regards,
> Joe Gwinn

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