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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