Wikibooks

Celestia/Celx Scripting/CELX Lua Methods/CEL command move

< Celestia | Celx Scripting | CELX Lua Methods

move

edit

move { duration <duration> velocity <vector> }

Move the camera at the specified <vector> velocity in km/sec for each of the X, Y and Z axes, for the specified <duration> in seconds.
A wait command is not necessary after a move command.

Arguments:

duration <duration>
Number of seconds to take during the move. No default.
velocity <vector>
Speed as defined for the currently active coordinate system, in km/second for each of the X, Y and Z axes in a vector [ < xspeed > < yspeed > < zspeed > ]. No default.
Positive and negative <vector> values are used to indicate forward and reverse respectively ("+" sign is not necessary for positive values).


CELX equivalent:

Based on the observer:goto(table) method.

Note: The given positions in the observer:goto(table) method are expected to be relative to the universal frame-of-reference, while the non table-based goto uses positions relative to the current frame-of-reference.

  • In CELX, positions are stored in millionths of a light year, so you have to convert km to millionths of a light year, using the "uly_to_km" constant.
uly_to_km = 9460730.4725808
  • Obtain observer instance of the active view and store in "obs".
obs = celestia:getobserver()
  • Determine the actual observer position and store in "frompos":
frompos = obs:getposition()
  • Determine the position to goto as follows:
    • Convert vector [ <xspeed> <yspeed> <zspeed> ] to millionths of a light year and store in "velocityvector".
    • Multiply "velocityvector" with <duration> seconds and add the result to the actual server position. The result must be stored in "topos".
velocityvector = celestia:newvector( <xspeed>/uly_to_km, <yspeed>/uly_to_km, <zspeed>/uly_to_km)
topos = frompos + <duration> * velocityvector
  • Define and initialize the parameter table as follows:
    • Determine the number of seconds the goto should take.
    • Obtain the current position of the observer = frompos (obtained 2 steps ago).
    • New position object = topos (obtained in previous step))
    • Obtain the current orientation of the observer.
    • Because CEL: move does not change the observer orientation, the final orientation is the same as the initial orientation.
    • Start adjusting the observer orientation after 0 percent of the time to goto (it’s the same orientation)
    • End adjusting the observer orientation after 0 percent of the time to goto (it’s the same orientation).
    • Spend 10% of the time for accelerating and decelerating
parameters={}
parameters.duration = <duration>
parameters.from = frompos
parameters.to = topos
parameters.initialOrientation = obs:getorientation()
orientation.parameters.finalOrientation = parameters.initialOrientation
parameters.startInterpolation = 0
parameters.endInterpolation = 0
parameters.accelTime = 0.1
  • Move the observer <duration> seconds towards target position.
obs:goto(parameters)
  • Wait <duration> seconds.
wait(parameters.duration)


Summarized: 

uly_to_km = 9460730.4725808
obs = celestia:getobserver()
frompos = obs:getposition()
velocityvector = celestia:newvector( <xspeed>/uly_to_km, <yspeed>/uly_to_km, <zspeed>/uly_to_km)
topos = frompos + <duration> * velocityvector
parameters = { }
parameters.duration = <duration>
parameters.from = frompos
parameters.to = topos
parameters.initialOrientation = obs:getorientation()
parameters.finalOrientation = parameters.initialOrientation
parameters.startInterpolation = 0
parameters.endInterpolation = 0
parameters.accelTime = 0.1
obs:goto(parameters)
wait(parameters.duration)


Summarized as a function: 

function move_obs(time, x, y, z)
   local uly_to_km = 9460730.4725808
   local obs = celestia:getobserver()
   local parameters = { }
   parameters.duration = time
   parameters.from = obs:getposition()
   local vector = celestia:newvector(x/uly_to_km, y/uly_to_km, z/uly_to_km)
   parameters.to = parameters.from + parameters.duration * vector
   parameters.initialOrientation = obs:getorientation()
   parameters.finalOrientation = parameters.initialOrientation
   parameters.startInterpolation = 0
   parameters.endInterpolation = 0
   parameters.accelTime = 0.1
   obs:goto(parameters)
   wait(time)
end

move_obs( <duration>, <xspeed>, <yspeed>, <zspeed> )


Example:
This example selects the Earth and positions the camera over Seattle, Washington, USA.
Then moves the camera for 10 seconds as follows:

  • along the X axis at a speed of 1000 km/second.
  • along the Y axis at a speed of 2000 km/second.
  • along the Z axis at a speed of 1500 km/second.

CEL: 

select      { object "Sol/Earth" }
synchronous { }
gotolonglat { time 5 distance 3 up [0 1 0] longitude -122 latitude 47 }
print       { text "Traveling to Seattle, Washington, USA."
              row -3 column 1 duration 5 }
wait        { duration 5 }
move        { duration 10  velocity [ 500 1000 750 ] }

CELX with the observer:goto(table) method: 

earth = celestia:find("Sol/Earth")
celestia:select(earth)
obs = celestia:getobserver()
obs:synchronous(earth)
earthradius = earth:radius()
earthdistance = 3 * earthradius
longitude = -122 * math.pi/180
latitude = 47 * math.pi/180
obs:gotolonglat(earth, longitude, latitude, earthdistance, 5.0)
celestia:print("Traveling to Seattle, Washington, USA.", 5.0, -1, -1, 1, 3)
wait(5.0)
uly_to_km = 9460730.4725808
obs = celestia:getobserver()
frompos = obs:getposition()
velocityvector = celestia:newvector( 500/uly_to_km, 1000/uly_to_km, 750/uly_to_km)
topos = frompos + 10 * velocityvector
parameters = { }
parameters.duration = 10
parameters.from = frompos
parameters.to = topos
parameters.initialOrientation = obs:getorientation()
parameters.finalOrientation = parameters.initialOrientation
parameters.startInterpolation = 0
parameters.endInterpolation = 0
parameters.accelTime = 0.1
obs:goto(parameters)
wait(parameters.duration)

CELX with the observer:goto(table) method in a function: 

function move_obs(time, x, y, z)
  local obs = celestia:getobserver()
  local uly_to_km = 9460730.4725808
  local parameters = { }
  parameters.duration = time
  parameters.from = obs:getposition()
  local vector = celestia:newvector(x/uly_to_km, y/uly_to_km, z/uly_to_km)
  parameters.to = parameters.from + parameters.duration * vector
  parameters.initialOrientation = obs:getorientation()
  parameters.finalOrientation = parameters.initialOrientation
  parameters.startInterpolation = 0
  parameters.endInterpolation = 0
  parameters.accelTime = 0.1
  obs:goto(parameters)
  wait(time)
end

earth = celestia:find("Sol/Earth")
celestia:select(earth)
obs = celestia:getobserver()
obs:synchronous(earth)
earthradius = earth:radius()
earthdistance = 3 * earthradius
longitude = -122 * math.pi/180
latitude = 47 * math.pi/180
obs:gotolonglat(earth, longitude, latitude, earthdistance, 5.0)
celestia:print("Traveling to Seattle, Washington, USA.", 5.0, -1, -1, 1, 3)
wait(5.0)
move_obs(10, 500, 1000, 750)


Back to CEL command index

Retrieved from "https://en.wikibooks.org/w/index.php?title=Celestia/Celx_Scripting/CELX_Lua_Methods/CEL_command_move&oldid=3584916"