Rotate 3D Graphics View - wrong center of rotation

Fred shared this problem 3 months ago
Not a Problem

1) I would expect that the UI-tool 'Rotate 3D graphics View' should rotate around point (0,0,0).

However, it rotates around point (0, 0, 1.5).

2) When 'moving the 3D graphics view', the rotation point still remains the same point on the screen. I would expect it to move along with the (0,0,0) point.

Comments (7)

photo
1

I think that would be strange - imagine if (0,0,0) was off-screen

photo
1

Hi Michael,

Thanks for looking into this.

Maybe it depends on the use-case, and how you use the coordinate system. But it does rotate around (0,0) in XY, so why around z=1.5 in the other planes? At least it would be more consistent to do the same in all coordinates?

photo
1

It will, you just need to make sure (0,0,0) is in the centre of the view.


That will be easier to set soon - try this test link https://www.geogebra.org/m/...

photo
1

Hi Michael,


The behavior of your test program is OK for me. It would solve my problem.

You can see the current behavior(Classic 5.x) of your test case here while drag-rotating the 3d View.

Fyi: I currently use Geogebra to validate 3D models of human heads by drawing a 3D view over a 2D photo , as in this example: I make the Geogebra window transparent so that the photo acts as a background, and then I rotate the model to check it. For this, I need the rotation point to be stable, otherwise I need to reposition both photo and geogebra all the time.

photo
1

That's very cool! Do you have any finished examples you could share?

photo
1

It is really getting too clumsy (depending on external tools) to be practical. I am now using 2D (because I can insert an image in 2D graph as background). I do the projection stuff in code. This works, but I need to insert images manually each time, which is still too clumsy. I hope to find a way to insert an image with a script or maybe by injecting into the ggb file or something else (any ideas welcome...). Then I would happily provide a sample.

photo
1

do you know some youtube or similar that shows the process?

photo
© 2021 International GeoGebra Institute