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Rotate vetically, sometimes yes, sometimes not

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91669] Rotate vetically, sometimes yes, sometimes not
  • From: "E. Martin-Serrano" <eMartinSerrano at telefonica.net>
  • Date: Wed, 3 Sep 2008 06:46:05 -0400 (EDT)

Hi,

(Sorry discard, the previous email. As, I hit enter the whole text messed up
since it was full of non standard characters incompatible with the typical
email plain text)

First, thanks to Wolfram for the info about Manipulate. Seems they sent to
me all what they have. Thanks again.



Now, please,



Find in the Documentation Center the entry =93Interacting with 3D Graphic
and go to the section Rotate About the Axis Perpendicular to the Screen.
There, one can read: You can also rotate 3D objects about the axis
perpendicular to the screen with your mouse, and Move the pointer to a
corner of the display area of the 3D graphic., and The pointer changes to
the 3D vertical rotate pointer, and  Click and move the pointer clockwise
or counterclockwise.



OK.



If you do that on the graphics3D object generated by



p3d = Plot3D[Sin[x =
y],{x,0,3},{y,0,3},ColorFunction->"Rainbow",Mesh->None] ,




the pointer does not change to the 3D vertical rotate pointer, but it
remains as the 3D rotate pointer instead. If one performs



FullGraphics[p3d]//InputForm



One gets the following at the bottom of the output:



Method -> {"RotationControl" -> "Globe"}



This seems to be a non documented option/feature or whatever; since neither
Method -> {"RotationControl" -> "Globe"} nor "RotationControl" are in the
Documentation Center. So:

1)      It sounds as if  <<Method -> {"RotationControl" -> "Globe"}>> were
the reason why the pointer does not change to 3D vertical rotate pointer,
but remains as the 3D rotate pointer instead. The first side (intended)
effect is that Plot3D objects cannot be rotated in this way. Why not?

2)      Other side effect is: if several different 3D graphics are merged
with Show, the whole picture does not rotate vertically if one does not take
special care in the order given to the parameters in Show and one with
<<Method -> {"RotationControl" -> "Globe"}>>  happens to be in the first
position in the parameter list. If so, then nothing works as wanted. Anyway,
to be able to control the possibility of rotating the resulting compound 3D
graphics object, one has to know in advance whether the option <<Method ->
{"RotationControl" -> "Globe"}>> was or not in the merged pictures and what
its meaning is. In any case this is a strong restriction for Show because
the order of the parameters matters a lot.



Apart from the fact that one must necessarily dive into the inner and
detailed data of the graphics objects just to guess what is going on, it
contradicts the general statement You can also rotate 3D objects about the
axis perpendicular to the screen with your mouse, since, there is at least
one exception and it should have been documented. Besides, I am not sure
whether it is the actual reason why that 3D plot does not rotate about the
axis perpendicular to the screen. Of course, <<Method -> {"RotationControl"
-> "Globe"}>> has been generated by Mathematica. So it is the default
setting. Can it be overridden?



By the way, this drawback (?) can be cleanly avoided by using the
Prestantions package by David Park.



Needs["Presentations`Master`"]

Draw3DItems[ Draw3D[Sin[x
y],{x,0,3},{y,0,3},ColorFunction->"Rainbow",Mesh->None ]]  works perfectly,
as expected.



While



Show[Plot3D[Sin[x y],{x,0,3},{y,0,3},ColorFunction->"Rainbow",Mesh->None ]]
does not work either.



Any help?



E. Mart=EDn-Serrano




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