[SOLVED] How to have stars filter through the sun ?

[K.Wagrez]

Hello everyone,

While going through our list of tweaks and fixes, I stumbled upon a regression for our night sky. Currently we have a stars billboard that follows the user, with a correct visibility distance and correct tweaks. The material of this star billboard is set to Alpha test transparency.

At some point it worked, and filtered through the sun environment skybox, but it doesn't work anymore. It broke somewhat during the 2.6 to 2.18 migration, and we may have lost the understanding or the secret behind how it worked.

If I wanted, with the 2.19.1, to have my star billboard filter through the sun sky, based on the hour of the day, how would I go about it ?

[arizmenda]

Hey there,

Yeah, quite a few versions have gone by since then, the environment settings, textures (including the sun one), scattering system and a lot more have changed quite a bit.

Could you clarify which sky setup you're using? Is it the regular skybox?

Also, if you could share a short video or a few screenshots, and the custom textures (if you're using those) that would help a lot.

Even better if you have a comparison of how it looked before vs. how it looks now - that would make it much easier to figure out what broke. 

[K.Wagrez]

We have no custom texture or skybox, we just have a stars billboard, a sun and a moon. I'm not sure I saw a page in Unigine's documentatino explaining how to have stars during dawn or dusk.

I'm going to try screenshots of the past application with stars in the sky, but that might be difficult.

I also join the render settings we commonly use and the material we assigned to our billboard. We use the diffuse texture generated by the star billboard, as explained in the documentation.

rendersettings_skyandstars.render stars.mat

[arizmenda]

Thanks for the extra details and the files.

I went ahead and used the render preset and the material you attached, here is what I’m getting on my side (I changed the sun texture a bit and increased the star size slightly just to make the result easier to see):

At this point, it’s still not clear what exactly is supposed to be wrong. Could you point out what in this image does not match your expected result?

It would really help if you could share a screenshot of how it currently looks for you (with the issue).

Thanks!

[K.Wagrez]

Well, it's simple. I don't see any star. I know they're, since when you select the billboard you got the colliders around the particles that briefly shine, but I don't see them.
I can see them if I use Opaque instead of Alpha test in the material. But Alpha test was the original setting, and our goal was to make the stars visible when the sun is low, not in broad daylight.

'Opaque star system" works, but that's not what we had in the past, nor what we want:


But in Alpha test, no more stars. And our goal is to make them star appearing at dusk, like that:



From what I gather, it was working in the past, but I wasn't in the company, and apparently we lost the people responsible for this.

[arizmenda]

Have you checked the Alpha channel value in the diffuse settings? Sometimes after a migration the value may change, especially if there were any changes related to those settings.

The value should be higher than around 130 for the star material to become visible.

 

[K.Wagrez]

Well, with alpha > 130 the stars are visible at all time, even in daylight. And in the night when turning my head I can have all the stars suddenly changing brightness (or disappearing). I tried different settings, nothing works consistently.

I thought it would be an easy fix but it took me too much time. For now I will stop working on this question. I will let the 3D artists come back here to fix this, and I will investigate if our "stars" have really been working at some point.

Sorry for wasting your time arizmenda

[arizmenda]

No worries at all! These small "worked before, now it doesn’t" situations are exactly the tricky ones. :)

One thing I’d like to check before you step away from it: was the star billboard material ever tied to a Tracker, or some scripted weather/lighting controller?

If your project had any .track files before the migration, it’s possible that one of those didn’t migrate fully, and the automatic fade-in/out just isn’t happening anymore.
If that’s the case, it’s totally fine - you can either restore the old track or create a new one to control the star material params according the time of the day again.

[K.Wagrez]

In terms of Unigine scripts we didn't have any internal logic (I checked). I haven't seen any track file or use of any Tracker, but I might have missed that. I will check if we have something like that lurking somewhere.

[K.Wagrez]

Okay @arizmenda I found how we did.

So yeah, we had a track file that just enabled the diffuse color at some point in time (in a brutish manner). And people forgot it was there, and it was lost to time, in a folder somewhere.

I really thought we had something a little smarter than this (like alpha blending slowly with the amount of sunlight) but nope.

Again, sorry for taking your time :). 

[arizmenda]

Great! Glad you found it - happy to help!