ScriptedOrbit tutorial
Re: Three Lissajous curves
Fenerit,
the trouble I'm describing is seen when you follow the pink ball and watch Eros approaching (use the link I gave). Not the reverse. The video above can't show the problem.
the trouble I'm describing is seen when you follow the pink ball and watch Eros approaching (use the link I gave). Not the reverse. The video above can't show the problem.
"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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Topic authorFenerit
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Re: Three Lissajous curves
Cham wrote:Fenerit,
the trouble I'm describing is seen when you follow the pink ball and watch Eros approaching (use the link I gave). Not the reverse. The video above can't show the problem.
Cham, I see that, and I see also that a galaxy appear in my visual. They are math issues; there are tangents in the module. But as long as the motion is assigned to an object instead of a camera, this latter is free to accomplish another motion...
![Wink :wink:](./images/smilies/icon_wink.gif)
Last edited by Fenerit on 11.10.2009, 16:51, edited 1 time in total.
Never at rest.
Massimo
Massimo
Re: Three Lissajous curves
Yep, the maths aren't right. But once it is solved, it could let the user to travel into a spaceship through the whole universe !
The scriptedOrbit introduces the posibility to move a spaceship between several stars !![Surprised :o](./images/smilies/icon_surprised.gif)
![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
The scriptedOrbit introduces the posibility to move a spaceship between several stars !
![Surprised :o](./images/smilies/icon_surprised.gif)
"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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Topic authorFenerit
- Posts: 1880
- Joined: 26.03.2007
- Age: 17
- With us: 17 years 5 months
- Location: Thyrrenian sea
Re: Three Lissajous curves
Well, indeed. But today my attitude was "sci-fi movies" like. I'm not a math genius, but also myself think that someone would develop more equations, so to say, to make a sort of "math pack" for these orbits.
Never at rest.
Massimo
Massimo
Re: Three Lissajous curves
I'm playing with it right now. I'm changing the motion to all sorts of trajectories. I don't understand the syntax yet, though.
"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!"
Re: Three Lissajous curves
Ok, I now understand the maths. My test trajectory is working as expected. Expect some very cool new things from this technique !
What are the units used in the SSC for all the parameters ? What are the units of PeriodX, Y and Z ?
And what about AmplitudeX, Y, Z ?
EDIT : I'll be able to define precessing orbits (relativistic perihelion advance for some pulsars, for example), volcano ejecta with CMOD sprites, solar protuberances, spiraling motion to a black hole, etc... and maybe even this :
http://antwrp.gsfc.nasa.gov/apod/ap060726.html
http://demonstrations.wolfram.com/MassT ... arSystems/
![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
![Wink :wink:](./images/smilies/icon_wink.gif)
What are the units used in the SSC for all the parameters ? What are the units of PeriodX, Y and Z ?
And what about AmplitudeX, Y, Z ?
EDIT : I'll be able to define precessing orbits (relativistic perihelion advance for some pulsars, for example), volcano ejecta with CMOD sprites, solar protuberances, spiraling motion to a black hole, etc... and maybe even this :
http://antwrp.gsfc.nasa.gov/apod/ap060726.html
http://demonstrations.wolfram.com/MassT ... arSystems/
![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
"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!"
Re: Three Lissajous curves
There's a math library there, which will be very usefull to built complicated orbits :
http://lua-users.org/wiki/MathLibraryTutorial
Fenerit, please, edit the title of this thread so it reads something like "Scripted Orbit Tutorial"...
http://lua-users.org/wiki/MathLibraryTutorial
Fenerit, please, edit the title of this thread so it reads something like "Scripted Orbit Tutorial"...
Last edited by Cham on 11.10.2009, 18:29, edited 2 times in total.
"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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Topic authorFenerit
- Posts: 1880
- Joined: 26.03.2007
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- With us: 17 years 5 months
- Location: Thyrrenian sea
Re: Three Lissajous curves
I can't wait!
Amplitude and Phase are in km, instead, for what concern Period it I'm not sure but might be days. Anyhow, I noticed a thing: for speed movements in realtime is best to deal with the last decimals as were "frame rates" i.e 24, 25, 29.7, 30 fps.
Ahem, I don't know how to do for changing the title of the topic...![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
![Very Happy :D](./images/smilies/icon_biggrin.gif)
Ahem, I don't know how to do for changing the title of the topic...
![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
Never at rest.
Massimo
Massimo
Re: Three Lissajous curves
Fenerit wrote:I don't know how to do for changing the title of the topic...
Just edit your first message. The title is available there.
"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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Topic authorFenerit
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- With us: 17 years 5 months
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Re: ScriptedOrbit tutorial
The title of this topic has been changed from "Three Lissajous curves" to "ScriptedOrbit tutorial".
Never at rest.
Massimo
Massimo
Re: ScriptedOrbit tutorial
Now, someone needs to state the exact units of all variables used in the SSC, for any scripted orbit :
1. Time variable "t" (is it in "days" of 24 hours ?)
2. Amplitude (km ?)
3. Phase (degrees ? Radians ??)
4. PeriodX... (I guess it's the same unit as for the time variable ?)
Are the units dependant of the reference frame ?
And can we introduce any other parameters in the SSC ? For example, the unitless parameters called "Damping" and "Omega" below :
EDIT : Apparently, the answer to the last question is YES, according to some test I just made a min ago. So this is good.
For reference : Maths library there :
http://lua-users.org/wiki/MathLibraryTutorial
1. Time variable "t" (is it in "days" of 24 hours ?)
2. Amplitude (km ?)
3. Phase (degrees ? Radians ??)
4. PeriodX... (I guess it's the same unit as for the time variable ?)
Are the units dependant of the reference frame ?
And can we introduce any other parameters in the SSC ? For example, the unitless parameters called "Damping" and "Omega" below :
Code: Select all
"TestBall" "Sol/Eros"
{
Class "spacecraft"
Radius 1
Color [ 1 0 1 ]
OrbitFrame { BodyFixed { Center "Sol/Eros" } }
BodyFrame { BodyFixed { Center "Sol/Eros" } }
ScriptedOrbit {
Module "Test_trajectory"
Function "Test_trajectory"
PeriodX 1
PeriodY 1
PeriodZ 1
PhaseX 0
PhaseY 0
PhaseZ 0
AmplitudeX 100
AmplitudeY 100
AmplitudeZ 100
Damping 5
Omega 2
}
}
EDIT : Apparently, the answer to the last question is YES, according to some test I just made a min ago. So this is good.
For reference : Maths library there :
http://lua-users.org/wiki/MathLibraryTutorial
"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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Topic authorFenerit
- Posts: 1880
- Joined: 26.03.2007
- Age: 17
- With us: 17 years 5 months
- Location: Thyrrenian sea
Re: ScriptedOrbit tutorial
A short description of ScriptedOrbit is here: http://en.wikibooks.org/wiki/Celestia/Trajectories#SampledOrbit ; Phase seem in radiants. t (current julian day)
Never at rest.
Massimo
Massimo
Re: ScriptedOrbit tutorial
OMG ! This is pretty impressive ! Look at this UFO traveling all around the world.
Download link :
http://fsgregs.startlogic.com/Public_Files/Cham/UFO.zip (3.1 MB)
![Image](http://fsgregs.startlogic.com/Public_Files/Cham/Pictures/UFO.jpg)
Use this URL to follow the fast puppy !
cel://PhaseLock/Sol:Earth:UFO/Sol:Earth ... rc=0&ver=3
Accelerate time 10 fold, and get away to see the large scale motion all around the world. This orbit isn't circular (well, this is the whole point of a scriptedOrbit !). The parameters used in the SSC file could be changed (especially the Omega1 and Omega2 parameters), and see the various effects you can achieve. Talk about a non-geodesic path !![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
Download link :
http://fsgregs.startlogic.com/Public_Files/Cham/UFO.zip (3.1 MB)
![Image](http://fsgregs.startlogic.com/Public_Files/Cham/Pictures/UFO.jpg)
Use this URL to follow the fast puppy !
cel://PhaseLock/Sol:Earth:UFO/Sol:Earth ... rc=0&ver=3
Accelerate time 10 fold, and get away to see the large scale motion all around the world. This orbit isn't circular (well, this is the whole point of a scriptedOrbit !). The parameters used in the SSC file could be changed (especially the Omega1 and Omega2 parameters), and see the various effects you can achieve. Talk about a non-geodesic path !
![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
"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!"
Re: ScriptedOrbit tutorial
For the previous example, here's the SSC code used, and its scripted trajectory in a simplified form :
The scripted orbit :
Code: Select all
"UFO" "Sol/Earth"
{
Class "spacecraft"
Mesh "UFO.cmod"
Orientation [90 1 0 0]
Radius 0.05
Albedo 0.6
OrbitFrame { BodyFixed { Center "Sol/Earth" } }
BodyFrame { BodyFixed { Center "Sol/Earth" } }
ScriptedOrbit {
Module "UFO_trajectory"
Function "UFO_trajectory"
OrbitalRadius 6600
OrbitalPeriod 0.003
Omega1 5
Omega2 -7
}
UniformRotation {
Period 0.005
}
}
# The code below is a constraint on the spacecraft orientation
Modify "UFO" "Sol/Earth"
{
BodyFrame
{
TwoVector
{
Center "Sol/Earth/UFO"
Primary
{
Axis "z"
RelativePosition {
Observer "Sol/Earth/UFO"
Target "Sol/Earth"
}
}
Secondary
{
Axis "-x"
RelativeVelocity {
Observer "Sol/Earth/OVNI"
Target "Sol/Earth"
}
}
}
}
}
The scripted orbit :
Code: Select all
function UFO_trajectory(t)
-- Create a new table
local orbit = {};
-- Save the parameter list
orbit.params = t;
-- Set the required fields boundingRadius and position; note that position is actually a function
-- Compute the bounding radius from the SSC parameters
orbit.boundingRadius = t.OrbitalRadius
-- The position function will be called whenever Celestia needs the position of the object
function orbit:position(tjd)
local t = tjd - 2451545.0
local pi2 = math.pi * 2;
local x = self.params.OrbitalRadius * math.cos(self.params.Omega2 * t / self.params.OrbitalPeriod) * math.cos(self.params.Omega1 * t / self.params.OrbitalPeriod)
local y = self.params.OrbitalRadius * math.sin(self.params.Omega1 * t / self.params.OrbitalPeriod)
local z = self.params.OrbitalRadius * math.sin(self.params.Omega2 * t / self.params.OrbitalPeriod) * math.cos(self.params.Omega1 * t / self.params.OrbitalPeriod)
return x, y, z
end
return orbit
end
"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!"
-
Topic authorFenerit
- Posts: 1880
- Joined: 26.03.2007
- Age: 17
- With us: 17 years 5 months
- Location: Thyrrenian sea
Re: ScriptedOrbit tutorial
Interesting.
Now we can track airlines flies
Instead, this code show rectilinear alternate motions along XYZ axis rispectively.
scriptorbit.ssc
uniform_motion.lua module:
![Cool 8)](./images/smilies/icon_cool.gif)
![Mr. Green :mrgreen:](./images/smilies/icon_mrgreen.gif)
Instead, this code show rectilinear alternate motions along XYZ axis rispectively.
scriptorbit.ssc
Code: Select all
"Uniform X" "Sol/Eros"
{
Class "spacecraft"
Radius 1
Color [ 1 0 0 ]
OrbitFrame { BodyFixed { Center "Sol/Eros" } }
BodyFrame { BodyFixed { Center "Sol/Eros" } }
ScriptedOrbit
{
Module "uniform_motion"
Function "uniform_motion"
PeriodX 0.000025
PeriodY 0.000025
PeriodZ 0.000025
PhaseX 0
PhaseY 0
PhaseZ 0
AmplitudeX 50 # length of motion in km
AmplitudeY 0
AmplitudeZ 0
}
}
"Uniform Y" "Sol/Eros"
{
Class "spacecraft"
Radius 1
Color [ 1 0 0 ]
OrbitFrame { BodyFixed { Center "Sol/Eros" } }
BodyFrame { BodyFixed { Center "Sol/Eros" } }
ScriptedOrbit
{
Module "uniform_motion"
Function "uniform_motion"
PeriodX 0.000025
PeriodY 0.000025
PeriodZ 0.000025
PhaseX 0
PhaseY 0
PhaseZ 0
AmplitudeX 0
AmplitudeY 50 # length of motion in km
AmplitudeZ 0
}
}
"Uniform Z" "Sol/Eros"
{
Class "spacecraft"
Radius 1
Color [ 1 0 0 ]
OrbitFrame { BodyFixed { Center "Sol/Eros" } }
BodyFrame { BodyFixed { Center "Sol/Eros" } }
ScriptedOrbit
{
Module "uniform_motion"
Function "uniform_motion"
PeriodX 0.000025
PeriodY 0.000025
PeriodZ 0.000025
PhaseX 0
PhaseY 0
PhaseZ 0
AmplitudeX 0
AmplitudeY 0
AmplitudeZ 50 # length of motion in km
}
}
uniform_motion.lua module:
Code: Select all
function uniform_motion(t)
-- Create a new table
local orbit = {};
-- Save the parameter list
orbit.params = t;
-- Set the required fields boundingRadius and position; note that position is actually a function
-- Compute the bounding radius from the amplitudes
orbit.boundingRadius =
math.sqrt(t.AmplitudeX * t.AmplitudeX + t.AmplitudeY * t.AmplitudeY + t.AmplitudeZ * t.AmplitudeZ)
-- The position function will be called whenever Celestia needs the position of the object
function orbit:position(tjd)
local t = tjd - 2451545.0
local x = self.params.AmplitudeX * math.sin (t / self.params.PeriodZ - self.params.PhaseZ) * math.cos (self.params.AmplitudeZ)
local y = self.params.AmplitudeY * math.sin (t / self.params.PeriodZ - self.params.PhaseZ) * math.cos (self.params.AmplitudeX)
local z = self.params.AmplitudeZ * math.sin (t / self.params.PeriodZ - self.params.PhaseZ) * math.cos (self.params.AmplitudeY)
return x, y, z
end
return orbit
end
Never at rest.
Massimo
Massimo
Re: ScriptedOrbit tutorial
Try this code. Gives lots of funny trajectories around a planet :
UFO_trajectory.lua code :
SSC code :
UFO_trajectory.lua code :
Code: Select all
function spherical_trajectory(t)
-- Create a new table
local orbit = {};
-- Save the parameter list
orbit.params = t;
-- Set the required fields boundingRadius and position; note that position is actually a function
-- Compute the bounding radius from the SSC parameters
orbit.boundingRadius = t.OrbitalRadius
-- The position function will be called whenever Celestia needs the position of the object
function orbit:position(tjd)
local t = tjd - 2451545.0
local pi2 = math.pi * 2;
local Theta = 1/4 + self.params.LatAngle * math.cos(pi2 * self.params.LatFrequency * t / self.params.OrbitalPeriod);
local Phi = self.params.LongFrequency * t + self.params.LongAngle * math.cos(pi2 * self.params.LongVariation * t / self.params.OrbitalPeriod);
local x = self.params.OrbitalRadius * math.sin(pi2 * Theta) * math.cos(pi2 * Phi)
local y = self.params.OrbitalRadius * math.sin(pi2 * Theta) * math.sin(pi2 * Phi)
local z = self.params.OrbitalRadius * math.cos(pi2 * Theta)
return x, y, z
end
return orbit
end
SSC code :
Code: Select all
"Mad UFO" "Sol/Earth"
{
Class "spacecraft"
Mesh "UFO.cmod"
Orientation [90 1 0 0]
Radius 0.05
Albedo 0.6
OrbitFrame { BodyFixed { Center "Sol/Earth" } }
BodyFrame { BodyFixed { Center "Sol/Earth" } }
ScriptedOrbit {
Module "UFO_trajectory"
Function "spherical_trajectory"
OrbitalPeriod 0.03
OrbitalRadius 6995 # Radius of the sphere, in km
LongFrequency 300 # Main longitude frenquency
LatFrequency 100 # Main latitude frequency
LatAngle 0.02 # Max latitude angle, in units of 2Pi
LongVariation 600 # Secondary longitude frequency
LongAngle 0.01 # Longitude variation angle, in units of 2Pi
}
UniformRotation {
Period 0.005
}
}
"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!"
Re: ScriptedOrbit tutorial
Here's an update to the previous UFO addon (just replace the CELXX and SSC files with the ones below). The trajectory LUA files were cleaned and the parameters are a bit more general (to define motions on a sphere). We could do lots of interesting paths on a sphere with these. The SSC file is commented, so the parameters meaning should be clear.
"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!"
Re: ScriptedOrbit tutorial
ROFL !
Try this one !![Laughing :lol:](./images/smilies/icon_lol.gif)
Try this one !
![Laughing :lol:](./images/smilies/icon_lol.gif)
"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!"