Programming Question Please help with night activated engines

[Mr Martian]

Hey everyone, just playing around with some ideas for the SLS project i have started work on, and i want to give the launchpad spotlight effects at night, simmilar to the effect in AMSO or BrianJ's Delta II ad-on. To make the lights i have simply made some thrusters with no thrust and assigned them local light sources, but what i dont know what to do is turn the thrusters on at night, and off at day. I cant seemto be able to find anything on this in the orbiter api docs, so any help would be really appreciated thanks in advance

- Mr Martian

 

[Urwumpe]

... You can have local light sources without engines...

Also, for telling if it is night, I suggest you the following concept:

Normalize your relative position to the reference gravity body into a direction vector pointing "up".
Normalize your global position (The sun is effectively the center) into a direction vector pointing away from the sun.

If the scalar product (dotp) of these two vectors is positive, the sun is below the horizon. If it is positive and above a set threshold (cos(elevation_angle)), you can define what kind of night you want - eg, if you are interested in astronomical night.

 

[N_Molson]

I recommend not to use engines, because in some cases, even a ridiculously tiny thrust can cause the launchpad to bounce around like if it was a rubber castle. So I think it's better to stay safe and only use spotlights that will get activated/deactivated by the conditions you will set.

 

[Interceptor]

I would suggest to look at FOIs addons on OH,they have great looking night effects,such as spotlights,and also the beam effects,similar to AMSO-L-39pad effects.:thumbup:

 

[dgatsoulis]

In the code from a lua script by Wishbone, there is a function that checks if an object is in daylight or not. It shouldn't be too hard to transform into C++

Here is the code:

function is_in_daylight(obj)
   local retv
   local rs_angle -- rbody to sun angle
   local rh_angle -- rbody to horizon angle
   local rppos
   local rspos
   local obj_v = vessel.get_interface(obj)
   local body = obj_v:get_surfaceref()
   rppos = obj_v:get_relativepos(body)
   rh_angle = math.asin(oapi.get_size(body)/vec.length(rppos))
   rppos = vec.div(rppos,vec.length(rppos)) -- normalise
   local star = oapi.get_objhandle('Sun')
   rspos = obj_v:get_relativepos(star) -- sun position
   rspos = vec.div(rspos,vec.length(rspos)) -- normalise
   rs_angle = math.acos(vec.dotp(rppos,rspos))+(50/60*RAD)
   if (rs_angle > rh_angle) then
     retv = 1
   else
     retv = 0
   end
   return retv
end