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RE: Re: Locator 3D

  • To: mathgroup at
  • Subject: [mg83518] RE: [mg83508] Re: Locator 3D
  • From: "Ingolf Dahl" <ingolf.dahl at>
  • Date: Thu, 22 Nov 2007 04:42:08 -0500 (EST)
  • References: <fi0ndv$5c5$> <>
  • Reply-to: <ingolf.dahl at>

One could also think of locators with "object snap", in such a way that the
movement in the 3D case is confined to some graphic elements (points, lines
or surfaces), present in the 3D graphics. The movement of the locator can
then be controlled by the 2D position of the mouse in the image plane. But I
do not know how to implement that in Mathematica in a good way. One could
maybe imagine working on a freezed(=fixed viewpoint) 2D projection of the 3D
image, with ordinary 2D locators, and then search the graphics for 3D
objects with 2D projections in the neighborhood of the locator positions.
Another possibility is to have two freezed 2D projections from different
directions, with a common list of 3D locators, coupled to the 2D locators of
the two projections.
A third possibility is to use the mouse wheel, available on many mice. But
how to see where the locator is in the depth direction?
With all the clever programmers following MathGroup, maybe someone...

Best regards

Ingolf Dahl

-----Original Message-----
From: Szabolcs Horv=E1t [mailto:szhorvat at]
Sent: 21 November 2007 12:00
To: mathgroup at
Subject: [mg83518] [mg83508] Re: Locator 3D

roby.nowak at wrote:
> Hi everybody,
> is there something like a 3D Locator in Mathematica 6.0 ?
> how could such a thing be realised ?

The advantage of a Locator over something like

  Graphics[Point[{x, y}], PlotRange -> 1],
  {x, -1, 1}, {y, -1, 1}]

is that it can be directly moved with the mouse.  To easily move a point in
3D, one needs a special input device.  If you do have such a device, then
you might want to look at the documentation page
guide/GamepadAndDeviceInterface .  It should be possible to use it to move a
point in 3D, but I never had the chance to try this because I do not have
access to game pads.


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