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

lookback

lookback { }

Change the current camera view by 180 degrees (like a rear-view mirror).

The command has no arguments.

CELX equivalent:

Based on the observer:rotate() method.

• Define the axis up_vector for rotation and store in "up_vec".

up_v = celestia:newvector(0,1,0)

• Create new rotation around "up_vec" axis by 180 degrees = math.pi = 3.14159265 radians and store in "lookback".

lookback = celestia:newrotation(up_v, math.pi)

• Get observer instance of the active view and rotate observer according the new created rotation "lookback".

obs = celestia:getobserver()
obs:rotate(lookback)

Summarized:

up_v = celestia:newvector(0,1,0)
lookback = celestia:newrotation(up_v, math.pi)
obs = celestia:getobserver()
obs:rotate(lookback)

Example:
See the above CELX equivalent also as the CELX example for CEL: lookback { }.

CEL:

lookback { }

CELX with the observer:rotate() method:

up_v = celestia:newvector(0,1,0)
lookback = celestia:newrotation(up_v, math.pi)
obs = celestia:getobserver()
obs:rotate(lookback)

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