2.20 Stars/Night sky visible during day time

[Amerio.Stephane]

Hello,

In 2.20, the sky environment texture (stars) is fully alpha blended with the atmospheric sky. This leads to the day-time sky being fully black/full of stars, even at 1PM, if the stars visibility controlled by CIGI is too high (and this is starting at 10-20%...).

Moreover, at 100%, the stars/night sky are simply too bright, wayyyyy overexposed. While it was always a bit too high in previous version, now it's clearly overdone.

Also, the night sky is only visible when a new value from CIGI celestial is received.

Suggestions:

• the stars/night sky should be additive, not blended with the sky (maybe make it an option for compatibility if needed)
• at 100%, the night sky should appear as it would in a fully clear non polluted sky (aka from space), but not overtly bright

In our case, this new situation is problematic when interfacing with a 3rd party CIGI emitter we don't control that expect 100% stars = normal sky. Ouch, now the stars are visible during daytime and the sky is black.

Thanks!

[cash-metall]

Hello! 

You can change the intensity of the stars to 100% for your project and specification.

To do this you need to change alpha channel value in environment color param.

[Amerio.Stephane]

Gosh! 9 years with Unigine and you still show me new tricks! Thanks :)

[yurickon]

Я уже почти 4 года с UNIGINE, но тоже этого не знал) Для плавного вкл. и откл. звёзд использую вот такую конструкцию:

_d[0] += Game.IFps * 0.1f;
_stars_lerp.SetParameterFloat("billboard_scale", MathLib.Lerp(0, 0.28f, _d[0])); 

Век живи, век учись)

[Amerio.Stephane]

On 1/22/2026 at 8:08 AM, cash-metall said:

To do this you need to change alpha channel value in environment color param.

Alas, this doesn't work in IG mode, as the IG specifically will overwrite the alpha value when a IG Celestial control message is received.

Back to square one:

As you can see, at 2PM with the sun high in the sky and a stars intensity around 90%, the sky is black with starts visible (Alpha Blend mode):

Changing the Environment Blend mode to "Additive Blend" is not working either, because the stars are far too bright during the day:

 

 

Ideally, we'd like the stars to have the luminosity they currently have when alpha is set at 30% during night:

 

 

suggestion: add a new "alpha" coefficient to the Environment color, not controlled by the IG plugin..

(reminder: this is with a CIGI emitter we have no control over, sending 100% stars)

Edited January 25 by Amerio.Stephane

[cash-metall]

12 hours ago, Amerio.Stephane said:

Alas, this doesn't work in IG mode,

Yes indeed, I misled you. (For some reason I was sure that IG modifies this value with a multiplier, but it simply rewrites it).

so right now you can solve it only via code in postupdate somewere

int AppWorldLogic::postUpdate()
{
	Plugins::IG::SkyMap *skymap = Plugins::IG::Manager::get()->getSkyMap();
	float intensity = skymap->getStarfieldIntensity();
	skymap->setStarfieldIntensity(intensity * 0.1f);
	return 1;
}

 

[Amerio.Stephane]

Is there any way to know the actual sun & moon zenithal position, I mean like a percentage or some value like  0=horizon 1=zenith ? 

The goal would be to dynamically fine tune the night sky appearance...

[cash-metall]

11 hours ago, Amerio.Stephane said:

Is there any way to know the actual sun & moon zenithal position

sure

NodePtr sun = Manager::get()->getSkyMap()->getSunNode();
if (sun)
{
	float zenith = getAngle(vec3_up, sun->getDirection(AXIS_Z));
  //.....
}