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Old 23rd November 2013, 03:00 PM   #1
Terry Capps
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Question Object Location Confusion

I have noticed that, in a mildly complex model, the Object Properties Editor will show the wrong location for an object. In the attached image, I used the Object Properties Editor to find the location of the "Panel". I then pulled a model of a "Screw" from my Object Library and then used the Move To boxes to specify the same location as the Panel. The screw ended up in a different location than the panel, but the Object Properties Editor shows that they are in the same location.

If you do something like this while creating a new model with nothing but the panel and the screw in the model, the problem doesn't occur. The second object (in this case the screw) does get moved to the same location as the "Panel".

Anyone have any ideas about this?
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Old 24th November 2013, 11:11 AM   #2
Terry Capps
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Unhappy Re: Object Location Confusion

Now I am having trouble reproducing the problem with other models. It seems to be sporadic.

I am running ac3d 7.0.11 on an Intel Pentium Dual-Core E2140 using Windows XP-Pro. The PC is a Dell Inspiron 530 and the graphics are "built-in".

Last edited by Terry Capps; 24th November 2013 at 11:18 AM.
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Old 24th November 2013, 12:47 PM   #3
Andy
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Default Re: Object Location Confusion

You may be moving the object in vertex or surface edit modes. In those cases , the object center will not move with the geometry.
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Old 24th November 2013, 02:57 PM   #4
Terry Capps
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Default Re: Object Location Confusion

You're right!
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Old 24th November 2013, 10:25 PM   #5
Terry Capps
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Default Re: Object Location Confusion

Thanks for the quick reply, Andy.

I often model small real-world objects by inserting vertices at precise locations, building surfaces from them, and sometimes extruding surfaces. Occasionally, I had noticed that the object location (as specified by the Object Properties Editor) didn't seem right, but hadn't given it much thought until now.

The location specified by the Object Properties Editor is fine for simple objects (like boxes, spheres, or cylinders), but if you start with a surface and extrude it, ac3d keeps track of where the original location of the surface was (this is what shows in the Object Properties Editor) and then specs the location of each of the object vertices in respect to that original location.

If you select the object in object mode and then click on "Object, Re-centre", the location of the object (as shown in the Object Property Editor) will be corrected. If you have the Object Property Editor displayed, nothing will happen until you re-request it (F9).

Last edited by Terry Capps; 25th November 2013 at 10:22 PM.
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Old 25th November 2013, 07:29 AM   #6
Geoffm
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Default Re: Object Location Confusion

Fascinating. Which operations in AC3D actually use the location reported in the Object Property window? How is the location used? I have only ever used the centroid. What would happen if the location is set outside the object?

Minor Bug with the Property Editor visible on screen:
When you rotate the object manually using mouse click and drag the location updates when the mouse is released. The exact rotate (eg 30 degrees about Z) only changes the Loc xyz when the property Editor is re-requested (F9) .
This occurs even in Object mode. It should update for both tools.
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Old 1st December 2013, 12:12 AM   #7
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Default Re: Object Location Confusion

Quote:
Originally Posted by Geoffm View Post
Fascinating. Which operations in AC3D actually use the location reported in the Object Property window? How is the location used? I have only ever used the centroid. What would happen if the location is set outside the object?
The AC3d rotate tool can be set to use the Object Center, and it does not matter if the Object Center is inside the object or not.

Inside the .ac file each object is saved as if its Object Center was 0,0,0. Keeping the Object center near the object's bounding box can help keep file size down and precision up, for example, a vertex at (1000.1, 1000.1, 1000.1) would be stored as (0.1 ,0.1 ,0.1) if the vertex's containing object had its Object Center at (1000,1000,1000)

There is also a tool called 'adjust object centers...' that will quickly place the Object Center at minimum, maximum or centered on all 3 axises.

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