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Command to offset a model position on its orbit ?
Posted: 17.03.2005, 18:37
by Cham
I need the command to offset the position of a model center on its path. NOT the MeanAnomaly. It's something like OffSet, but I'm looking for position offset, not rotation offset.
Is it the command MeshCenter [ x x x ] ?
How does it work ?
Posted: 17.03.2005, 18:54
by Cham
By trial and error, I think I've found the answer, but please I need a confirmation :
In the command MeshCenter [ A B C ],
A represent the offset tangential to the orbit path,
B represent the offset along the orbital radius,
C represent the offset along the orbital plane perpendicular.
Is that right ? Selden ?
Posted: 17.03.2005, 20:46
by selden
Cham,
Sorry, all I know is that MeshCenter offsets the model with respect to its nominal center. You'll have to look at the source code to find out the exact coordinate system.
Posted: 17.03.2005, 20:48
by Cham
That's okay, Selden. I think my interpretation is right, and very natural, because it works very well right now, after some experimentations.
Posted: 18.03.2005, 14:10
by eburacum45
I was looking at that command myself; what magnitude of offset does it give and what is it measured in?
I want to model a spaceport with several different ships
(here is an early version)
http://tinypic.com/28p7gw
and this command might be useful in many ways.
Posted: 18.03.2005, 14:57
by Cham
I don't know what are the units. I don't think they're km.
Posted: 18.03.2005, 22:32
by TERRIER
Here is some information regarding the MeshCenter command;
Grant Hutchison wrote:MeshCenter has the syntax
MeshCenter [ x y z ]
where x, y and z are all all float values.
By default, Celestia builds a bounding box around a mesh object, and takes the centre of the bounding box to be the centre of the object. But various objects like moons, asteroids and spacecraft have their centre of gravity offset from the centre of the bounding box - in Celestia they'll rotate around the wrong axis, locations will appear in the wrong position, and Goto Object will take you to the wrong position. So you need to tell Celestia where you want the centre of the object to be, relative to the centre of the bounding box.
The coordinates x, y and z are the displacements for the object centre relative to the bounding box centre. You can find out what they should be from your modelling program. Some programs will give you the centre coordinates directly; for others, you'll need to work them out from the maximum and minimum coordinates of the mesh object.
Grant
I know that when using anim8or, if you click on an object to bring up the mesh editor, it gives you the location co-ordinates.
Posted: 19.03.2005, 21:00
by eburacum45
Thank you for that; I'll have a look into it with that in mind.