How to orient an SSC object parallel to the galactic plane ?

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Cham M
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Joined: 14.01.2004
Age: 53
With us: 14 years
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How to orient an SSC object parallel to the galactic plane ?

Post #1by Cham » 13.10.2011, 04:35

I need to orient an SSC object (a simple disk) so it's parallel to the galactic plane.

I can do it for a DSC object (it's easy with the Axis and Angle parameters), but not for an SSC object.

The SSC definition looks like this, but it needs to be edited so the object is oriented in the galactic coordinates system :

Code: Select all

"Galactic Polar Grid" "Sol"
{
   Class "diffuse"
   Mesh "polarGrid.cmod"
   # Emissive true
   Radius 1E7

   Orientation [90 1 0 0]
   FixedPosition [ 0 0 0 ]
   # FixedAttitude { }
   #RotationPeriod 0
   #RotationOffset 180
   #Obliquity 0
   UniformRotation {
      Period 0
      Inclination 0
      AscendingNode 0
      ArgOfPericenter 0
      MeanAnomaly 0
   }
}


Any idea ?
"Well! I've often seen a cat without a grin", thought Alice; "but a grin without a cat! It's the most curious thing I ever saw in all my life!"

Avatar
Topic author
Cham M
Posts: 4331
Joined: 14.01.2004
Age: 53
With us: 14 years
Location: Montreal

Re: How to orient an SSC object parallel to the galactic pla

Post #2by Cham » 13.10.2011, 14:56

By trial an errors, I've found that the following code gives a proper orientation. But I need to know the EXACT parameters for Celestia :

Code: Select all

"Galactic Polar Grid" "Sol"
{
   Class "diffuse"
   Mesh "polarGrid.cmod"
   # Emissive true
   Radius 1E7

   FixedPosition [ 0 0 0 ]
   Orientation [90 1 0 0]

   UniformRotation {
      Period      0
      Inclination   119.8  # Approximate
      AscendingNode   90  # Not sure this is right
      MeridianAngle   6.375  # Approximate
   }
}


EDIT : That SSC object is extremely usefull to properly move the camera, relative to the Milky Way, using a CELX script. By refering to the previous object, we could place the camera with exactly the right view (orientation), when we want to show some galactic distributions (Nebulae, Open Clusters, etc).
"Well! I've often seen a cat without a grin", thought Alice; "but a grin without a cat! It's the most curious thing I ever saw in all my life!"


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