Olander's Genesis Weather [Free]

No longer supported or provided.
Updated: 2024JAN07

Unity 2018.1 :: Imported and works perfectly (no change).

*For Time of Day users support has been removed for this.

Genesis Weather has been designed from the ground up to simulate a fairly realistic weather system per scene/game. Unlike all other weather systems you can find, Genesis Weather works for Any Planet, not just earth. You have complete control over how your weather should behave in your Scene/Game.

Genesis Weather also gives you fully functioning dynamic particle systems and audio that look and sound excellent. Since you have full source of everything you change swap out and change whatever you like. The choice is yours. Genesis Weather uses only minor shader adjustments to Standard Unity 5 shaders (Clouds/Stars are the exception). This means that during Unity updates there are far less chance of things breaking. Again, you have full source so chip away and change if you wish.

Unity 5-2017-2018 Compatible Versions:
v5.1.2 & v5.2.2 (You will need to revert/re-calibrate the Particle Systems)
v5.3.4+
v5.4.0+ (Demo Version works out of the box)
v5.6.0+ (for Legacy PostFX or Unity Post Effects Stack v1 with updated scripts below)
v2017+ (I stayed with PostFX Stack v1 in this)
v2018+ (Set up your Unity Post Effects Stack to v2)

Again...this design proves itself in High End Quality and Not breaking on Unity upgrades.

Camera Post FX Note:
I actually use Beautify, Amplify FXAA, and HBAO for my stack. I connect in Genesis Weather to it and it work flawlessly. This is for coders to do...but it is not difficult at all.

Unity Post FX Stack v1 and v2 are two different entities and are handled a bit differently from within Unity. There are a few scripts floating around that show how to connect...and more importantly...change the FX values at runtime. Unity uses a strange coding style to make it function...I suppose this is to not hit the GC during runtime.

This is a large system that handles All Sun and Weather. It has taken well over 1,500 hours to get fully working the way it should and be very well optimized. This also took an improvement from Unity itself to truly become what it needed to be.

Features:

• Full Source C#
• Full PDF Manuals that are full detailed with pictures and Step by Step Instructions
• Weather Manager Window that may be docked for ease of use.
  • Easy Setup with the click of a button and a couple drag to slots.
  • Default Setup is the Temperate Climate (most common)
• Designed to be Stand Alone...meaning very easy Integration into your own projects.
  • External Connections to proper variables are very simple...including database requirements.
• Dynamic Humidity and Temperature Simulation
  • Humidity controls most everything. This is based upon Relative Humidity and simple calculations have been done to keep the math simple and performance up.
  • Temperature dictates Rain, Rain and Snow Mix (+/- 1 Degree of 0), Snow
  • Cold Fronts condense air and cause precipitation
  • Warm Fronts expand ait to hold more moisture
• Simple Enable of Simulation for External Real World Humidity and Temperature control
• Celsius and Fahrenheit Temperatures in single decimal format. All calculations are in Celsius with automatic conversion
• Weather Zones that will change only the area they occupy in your scene. Great for Swamps and Mountains.
  • These basically override the global weather in the scene.
    
  • You may use as many of these as you wish.
  • These may also be network sync'd easily.
• Dynamic Sun Lighting and Intensity
  • Yellow (Earth), Blue, and Red Suns/Stars provided as defaults
• Dynamic Sun Rise and Sun Set Coloring
  
• Dynamic Clouds with full color grading based upon Sun Light conditions
  • Note: Volumetric 3D clouds were pulled because of rendering issues
  • There are 10 Cloud Patterns, 5 Noise Options to make a very large variety of clouds.
  • Clouds change at Night then color synchronize with weather level at Sun Rise
• Dynamic Sky Haze with both Static Override Haze and Event based
• Directional Cloud Movement based upon Wind Direction and Velocity
  • Clouds may be Rotated instead for simple situations
• Dynamic Atmospheric Fog
  • Grey (standard), Icy, and Dusty provided as defaults.
• Dynamic Ground Fog
  
• Dynamic Bloom
• Dynamic Depth of Field
• Dynamic Rain, Snow, and Sleet (2 Rain Audio Files)
  
• Dynamic Thunder (16 Audio Files)
• Dynamic Lightning and Flashes (3 Sets of Lightning...a lot of variety)

/******************************************************************************************************************/

Climate Configurations:
Temperature Zone (All Degrees in Celsius) is the Climate Zone of an Area
1 - Tropical 12 Months Warm 20 to 50
2 - Subtropical 8 Months Warm 20 to 35, 4 at 15 to 25
3 - Temperate 8 Months at 15 to 30, 4 at 2 to -10
4 - Cool 8 Months at 10 to 20, 4 at 10 to -5
5 - Cold 4 Months 5 to 10, 8 at 5 to -30
6 - Polar 12 Months -5 to -50
Default int 3

Precipitation Class is the Precipitaion Zone of an Area
0 - Arid - No Rain (even if Humidity is set)
1 - Semi Arid - Slight Summer Rain
2 - Arid Oceanic - Slight Winter Rain
3 - Oceanic - Winter Rain, Dry Summer
4 - Tropical - Summer Rain, Dry Winter
5 - Temperate - Rain in all Seasons
Default int 5

Minimum Temperature for the Area
Default float 15.0
Range -50.0 to 50.0 (capped by Temperature Zone)

Maximum Temperature for the Area
Default int 25.0
Range -50 to 50 (capped by Temperature Zone)

Area Water Content (in Percent)
Determines Fog and Clouds and helps tweak Precipitation
Default int 20 (% Water)
Range 0 to 100

NOTE: More than 40 will make it very likely to rain all the time

Hemisphere
For North (N) or South (S) of Equator
Default string N

Global Fog script note. Unity Image Effect GlobalFog.cs is set to not public. You must simply add the public in front of the class in the script. This will elevate the script to be able to be used by other systems.

 

Some Satiation Pics.

 

And some others.

 

And a couple more.
This is full on weather at 0.4C. Rain, Snow, and 90%+ humidity....~75fps <= incredible

 

Hi Folks.
Added pics of what this Genesis Weather System looks like. I completely underestimated the PDF Manual and had a few Weather Manager Window issues I completely forgot about as well. The Weather itself works extremely well and has proven very reliable and robust. This is a very complicated and dedicated system of work here. Thanks to all in the other forum for your patience while this has become....well....this.

Please have a look at the excellent pics above. Soon you will have this in your hands as well.

Cheers
O

 

@Olander This looks really cool! Congrats! I look forward to see how well this works on some mobile devices.

 

Hey! Actually the weather will mostly work fine since I pulled the Volumetric 3D clouds. The only thing that you may have to do is reduce the snow (just like before with the other version). The rain will probably be just fine. I did add particles to make the Fog so much better so that will be an informational test. The particles move slowly and they are much larger so those may be fine as well.

I will be looking forward to the testing on Mobile from yourself and others.

Thanks again for being patient!
Cheers
O

 

Well this sounds fascinating! Thx to @docsavage for mentioning! Guess I'll try it once it's out.

@Olander what's the plan for volumetric clouds? Add later? Does this include/do you plan crepuscular ray (sun shafts) based on humidity, etc?

Thx, R.

 

@Arkade
Thanks for stopping by.

1) Volumetric Clouds. There is really no good way to render the particles to get proper Sun Rise and Sun Set coloring of these. I made some really decent looking versions of these but just could not get them right. If the scene was more static (no day/night cycle) they work fine. Performance would be left for desktops since there are A Lot of particles being used. If you want to try to make them yourself you can use either my particle fog or ground fog to make them. Simply make them a cone with a 15deg angle and matrix them into a large rectangle. You will need roughly 25 of these particle fog cones with 15-17 active at any time inside the rectangle. Now simply move the rectangle across the sky at an elevation of your choosing. In a Medium Cloudy Day you could easily have 25-30 of these rectangles floating about in the sky.
Note: In testing with v5.4 it rendered very nicely but you could see the rendering pipeline being chewed to bits with these. We are not quite there yet technically.

Future Support/Addition:
1) Volumetric Particle Clouds...actually work if in a static lighted scene. Since I created a weather system for any planet that also has Day/Night then I cannot offer them to the table....even with known caveats. I would get sucked into supporting and working around Unity particle limitations and custom shaders.

2) Pseudo Volumetric Spherical Clouds...these are much better performance but look like crap when flying through them. Rendering these is tricky during Sun Rise and Sun Sets as well. Also since we are dealing with transparency in the spheres they just don't layer quite right during rendering. Close but in the end....just not right.

3) Layered Plane Volumetric Clouds...these look great from the ground and move with ease. They also render quite nicely...however...they are not acceptable for Fly Through applications because once you get into the clouds they look like Cloud Sandwiches.

v5.4+ in Unity has marked improvements in rendering...which gives us a chance with Volumetric Clouds #1. If the particles are changed a bit we may have a chance at finally having these for Day/Nights.

2) Sun Shafts. They do indeed work. Although I will not have them in the control scheme but they are fairly simple to add. This is a very subtle effect with respect to the clouds. This script adds some really nice shafts in forests and interiors. See the next post for the picture....also showing the clouds can be scaled smaller.
- Add the Unity Sun Shafts to the MainCamera
- Add an Empty Object and position this above all the Genesis Weather meshes. This Empty can move between ~10:00-14:00 vertically above the meshes
- Drag this empty to the Shafts Caster slot in the Sun Shafts MainCamera script.
- Set the intensity 15-20-ish

Hope that helps.
Cheers
O

 

Genesis Weather with Sun Shafts and the clouds have been scaled to the smaller scale.

Same exact scene with the clouds set to normal scale.

 

The Weather Manager(s) are finally complete and now the manual is getting its final touch ups.I have some more pics to wet the whistle. These next are showing off the Multiple Moons and Night Sky. I have included 8 Moons and 6 different galaxy sky textures for you to choose from. The moons each can have their own Orbit angle in Clockwise or Counter-Clockwise. Each may be scaled in the script and they have their own Axis Rotation as well in both Clockwise-Counter-Clockwise.
Enjoy

 

And some night shots of the various star fields.

 

Looking forward to it! Might integrate it in the Procedural Landscape Generator I started to build (which will also be available for free, once the base version is finished).

 

Genesis Weather is Now Released!

If you find any bugs or issues or even general comments. Please feel free to ask them right here.

Enjoy this really awesome weather simulation for your projects.
Cheers
O

 

Would be awesome to be integrated into your Procedural Landscape Generator. Should be really simple to do since Genesis Weather is really really simple to add to a scene. Have a look at the Add Weather to Scene button in the Weather Manager for info on how to tie that into your system....it will be REALLY easy.

Cheers
O

 

Hi Olander. It's really great of you to build something like this. We're curious if it is networked so that multiple players will see the same time of day and weather effects?

EDIT: Nevermind, I found your documentation after I asked.

 

Glad that you found it. One note about clients seeing the same weather. The entire system is built around having the exact same weather conditions on the dedicated server and all clients. So yes...fully networked. What cannot be networked are the particles. When they happen can but Which One specifically cannot. You could even network the same Thunder Audio but currently it is also random as well....but remember....the client will hear Thunder at the same time.

Hope that helps relieve a small caveat with the networking.

Cheers
O

 

Congrats on the release Olander !

I am seeing an error on Import, have searched the project but cannot find gGenesisDatabase

Assets/Genesis_Weather/Scripts/Weather/gWeatherData.cs(20,7): error CS0246: The type or namespace name `gGenesisDatabase' could not be found. Are you missing a using directive or an assembly reference?

EDIT: All good, have found Genesis Database online here but now getting the following errors:

Assets/Genesis_Weather/Scripts/Weather/gWeatherMaster.cs(53,5): error CS0118: `gWeatherMaster.GlobalFog' is a `field' but a `type' was expected
Assets/Genesis_Weather/Scripts/Weather/gWeatherSunCycle.cs(47,5): error CS0118: `gWeatherSunCycle.gTime' is a `field' but a `type' was expected
Assets/Genesis_Weather/Scripts/Weather/gWeatherZone.cs(55,5): error CS0118: `gWeatherZone.GlobalFog' is a `field' but a `type' was expected

I'm using Unity 5.4.0p4 on Mac El Capitan 10.11.6

EDIT2: Have fixed the above errors by making GlobalFog public in ImageEffects, and then also needed to install Olander's Genesis Time Control from here

Now getting this error:

Assets/Genesis_Weather/Scripts/Includes/gGenesisWeather.cs(2089,18): error CS0103: The name `gConversions' does not exist in the current context

 

1) Well...gWeatherData is no longer used really but is there for an example on remote data. It can be deleted...I will fix the unity package without this in it. No need for it in this version.

2) GlobalFog.cs is a common one. You made the right fix to make that script public. I will post a note about this in the initial posting on this forum and my site as well. Thank you for the reminder! I did this a really long time ago and forget about these things.

3) gTime should not be required....I see what is going on...because gTime is not in your project the script is still referencing this on line 47. So what you would need to do if you do not need a really nice time controller like Genesis Time....do this.
gWeatherSunCycle.cs line 47 comment out like so => //gTime gTime; then Find each gTime in that script and comment those out as well. No way around this really.

4) gGenesisWeather.cs : Looks like I missed one. I have my own library in the Genesis Framework and replicated functions that I needed to for Genesis Weather to be stand alone....here is the quick fix to this one.
Line 2089 change => fT = gConversions.FloatToRounded(fT, 1);
to => fT = ORW_FloatToRounded(fT, 1);

/*********************************************************************************************************/
Genesis Weather Package has been updated with the fixes 1) & 4) above. Thank you for posting!

Cheers
O

 

Thanks for this Olander. I've just downloaded and and look forward to playing with it when current project finished. Had a quick read of you views on 5.4 being a good improvement. Interesting to see a balanced view of UE4 and U5.4. To me it's amazing that all these tools U5, Ue4, Cryengine, blender, gimp etc are free.

Thanks Olander

 

hi @Olander
I've edited the fixes 2 and 3 but now i've got this:


new project with imageeffects added and genesis weather

 

@ghiboz
Well...that is my GenesisEditor.cs Include file from my framework that when I made the fixes above and exported the package (makes making Unity Editor stuff really easy)....I did not move back to weather. I am updating the package with this include file moved back. Just have to make sure this is on the checklist prior to exporting.

Here is the include file attached.
Cheers
O

 

thanks!!! in which folder must be?

 

now I've these:

Code (CSharp):

1. NullReferenceException: Object reference not set to an instance of an object
2. gWeatherMaster.SetFog () (at Assets/Genesis_Weather/Scripts/Weather/gWeatherMaster.cs:933)
3. gWeatherMaster.Update () (at Assets/Genesis_Weather/Scripts/Weather/gWeatherMaster.cs:581)

 

@ghiboz
That means that the GlobalFog script was not available when you made the WeatherMaster in the scene. You probably fixed the GlobalFog script after weather was added. So the reference to GlobalFog was not set. To fix this simply press the Delete Weather then add it back again. I just tested delete then add again and the reference is good here.

There is one other possibility...did you set the Name of your Main Camera which has the GlobalFog script on it in the weather manager? If that is not correct the error you have could be from that as well.

Cheers
O

 

I'll try to redo everything... the scene is the demo scene at the moment, and the globalfog is public

 

Right. So if the Global Fog was not fixed then the Demo Scene would not be able to see that Global Fog as an available reference. That has to be what happened.

To be honest I am not exactly certain why some of the Unity scripts are not set to public. Perhaps something just forgotten when these were updated to C#?

You should be able to simply press the Delete Weather Master button then Press the Add Weather to Scene button. That will fix it.

 

Where exactly do we need to make the GlobalFog change? I can't find anything in ImageEffects where this needs to be changed.

[EDIT]
Nevermind. Got it.

 

I'm now getting the following error:

Assets/Genesis_Weather/Scripts/Includes/gGenesisWeather.cs(372,13): error CS0103: The name `psRain' does not exist in the current context

[EDIT]
I see that it tries to access psRain.emissionRate if not UNITY_5_3_OR_NEWER, but the Unity version I'm testing on is 5.3.2f1. So, something strange there. I'll just remove the check there for now.

 

Now it complains about the following:

Assets/Genesis_Weather/Scripts/Weather/gWeatherSunCycle.cs(180,35): error CS1061: Type `gTime' does not contain a definition for `fDayHourStart' and no extension method `fDayHourStart' of type `gTime' could be found (are you missing a using directive or an assembly reference?)

Assets/Genesis_Weather/Scripts/Weather/gWeatherSunCycle.cs(181,33): error CS1061: Type `gTime' does not contain a definition for `fDayHourEnd' and no extension method `fDayHourEnd' of type `gTime' could be found (are you missing a using directive or an assembly reference?)

 

From above:
3) gTime should not be required....I see what is going on...because gTime is not in your project the script is still referencing this on line 47. So what you would need to do if you do not need a really nice time controller like Genesis Time....do this.
gWeatherSunCycle.cs line 47 comment out like so => //gTime gTime; then Find each gTime in that script and comment those out as well. No way around this really

Unity changed how the Particles work internally in the 'New' versions of Unity....keep them off the GC is what I read. They added that Unity clause in there but I only tested the weather with 5.1.2 which had the old particle code....which made me make that clause you stated. So you may be in a hybrid area in Unity for that clause. Only thing I can think of. Glad you found it though.

Cheers
O

 

I added the time control package already so that's not the issue. It has no problem finding things like nDayHourStart, but just has no clue about the float versions.

 

Got it! Took a moment but now that you say this! The gTime version I have running in my projects has been slightly converted from the version that was on the Asset Store which is what is available on my web site.

So what I will do is update that version to my current Framework version. I will also go ahead and 'Pre-Comment' out the gTime stuff in the default Genesis_Weather so that it will work without. Adding gTime later we will simply have to go back in and remove the comments to add it back in....same as what I had to do with the database portion. I'll update the package shortly.

Attached here is the updated gTime.cs that will solve your issue.
Thank you for reporting.
Cheers
O

 

hello @Olander
now the things starts to work!
I've tried dowloading now the latest package and works but not your demo that tell me the global fog problem
but Just one thing:
I've tried to do my scene from scratch and works, but I need to set the effects to my camera... I suggest you to write this in your user manual:

1. install effects
2. make public global fog script
3. install genesis weather
4. add global fog to the camera and sun shafts
5. start create genesis weather

 

@ghiboz
One question about the camera. The _MainCamera in the demo is already set up with all the effects and ordering...you may have your own camera....is this what you are talking about?
In the Demo Scene if Global Fog was not made public prior you just need to press the delete weather button then the add button and the references will fix themselves (whichever were missing).

I am updating the very beginning of the PDF Manual now to make this note....also will update near where the download links are to say this as well.

Thank You for posting on this.
Cheers
O

 

@Olander
i've made these steps:

1. create the new project
2. install effects
3. make public global fog script
4. install genesis weather
5. open demo scene

and gives the error of the global fog,
after this, if I create the new scene, with adding the effects to the camera, I create genesis weather and it works

 

@ghiboz
I now know what it is. Finally. What you are seeing is not the Demo Scene but it is the actual GlobalFog.cs script has changed in the latest Effects install package. I was using the one from the v5.1.2. I have now updated my project to the latest Image Effects as well. Does not help with the older versions of Unity but at least we know!

The Demo scene breaks upon import. Global Fog is losing the reference on the _MainCamera. To fix this…Add the GlobalFog script to the Script Field. Then click the Gear and choose Reset and set up as shown on Page 31. This will reset the GlobalFog Image Effect on the Main Camera.

Now in the Genesis Weather Manager....Press the Delete Weather button then Press the Add Weather button. Works just fine now.

Crazy stuff!

I have updated the PDF manual with this information as well....right at the top prior to the introduction.

Thank you for helping figure this out.
Cheers
O

 

@magique & @ghiboz
Again. Thank you to both for giving clues as to what the issues were during installation. I cannot thank enough for such excellent feedback.

Cheers and Regards
O

 

@Olander it's a pleasure help you in this project!

 

now seems almost ok!!!!!
another question: if I click the change clouds doesn't happen nothing... I think that I need to change the weather level, but if I set 3 or 4 it change back automatically to 1

good job!!!

 

Thank You for the compliment.

Clouds...while in Play Mode Simulation they will only transition different patterns at night. In Editor mode they will change instantly. Because of the way the rendering light works the clouds should not be allowed to transition at Sun Rise and Sun Set. So if you want to be able to change cloud patterns during the day hours then that could be changed/added...probably between 15-85% of the day hours.

Weather Level....this is determined from Humidity. If you want to change the Weather Level (Weather Relative Strength) then increase the Humidity. The percentages of each level change are in the manual.

Then weather system is very complex but....just remember that Humidity, Temperature Celsius, and the Weather Fronts control everything. It will take some time to get used to all the random features but each has an Override (Manual Mode) that you can set permanently or play around with to see what it actually does. Some settings are NOT in the Weather Manager since they are not really considered configurations....simply click on the Weather Master and have a look at the scripts in action on it. There is where all the fine tuning and really awesome controls are.

Let me know if you have questions on something.
Cheers
O

 

I will give it a go this weekend, looking forward implementing it!

 

hello @Olander
I was very busy and no time to test well your sublime package:

http://grally.net/wet-autumn/

I have a stupid question: the sun path is always perpendicular to the ground right? is not possible reduce the angle to have the midday not at the zenith?

my guess is not a real system like ToD that calculate the path depending by latitude longitude and date, but a parameter...

cheers

 

oh, last but not least...
since you've decided to publish your asset in your website, i tink that is a good idea set in the name of the link/file the version of genesis weater

 

Sorry a little late on the reply. Have been busy with a field project.

This one first....just checked all the linked from my web site for Genesis Weather. They all worked. There is only 1 version of the weather....what name should I change the 'Link' name to? Looking for advice on this one.

This one...sun is actually 23.5 degrees from directly overhead. If you would like the sun to arc lower across the sky simply change the Planetary Tilt number (In the Weather Sky Testing Group) to what you would like. This variable can be dynamically controlled as well by directly controlling => public float fPlanetTiltAngle = 23.5f; in gWeatherSunCycle.cs
Note: hundreds will be about all you want to control to with the tilt. ie.. 45.75 degrees would make the sun farther from vertical or basically...lower to the horizon.

One thing to note on the Sun Arc. I mentioned this in the PDF but worth mentioning again here. I am using Right Triangle Tangent math to make an arc across the sky. This is a very close approximation. Time of Day and Tenkoku (not certain how UniStorm is calculating the path) both are using Earth's Calculations and time of year to simulate the sun arc. While this is really nice this does not allow for other than earth planets. The sun will arc exactly the same.....every planet. Also another issue is that when hemispheres are flipped the calculations are incorrect. I have used both....Time of Day for a long time....they simply do not allow the full control of the sun arc without hacking into their code and disabling a number of things.

For some reading:
https://en.wikipedia.org/wiki/Sun_path
http://www.stjarnhimlen.se/comp/ppcomp.html

Let me know if you have any issues and any feedback you have once you get into testing weather. Will be interesting.

Cheers
O

 

thanlks!
my questiona about the versioning name is a 'todo', to make more clear the updates..

 

@ghiboz
Got it. Once we go to a v1.01 I will make certain to differ the versions. There will still only be one download though.
Appreciated.

And...since this is such a sublime weather system....who says we will have any updates after our initial situational issues? haha!!

Cheers
O

 

ahahahah!!!
i've a list of things to propose.....

 

hello again @Olander: I've tried with fPlanetTiltAngle , but it changes the path but at 12.00 is still to the zenith of the sky
another thing: the sky doesnt' follow the player, so if the player moves very far, may be go out of the skydome.

i've made a stupid test: a script that changes humidity and temperature, and I made rain, snow, but after, also putting 0 as humidty the snow can't stop dropping...

 

Planetary Tilt Angle....let us call this a bug. I will look into the math and do some checking. I did this a long time ago so I will go through each step of the calculation. Thank you for the report.

Cloud Meshes: You are correct, they do not move with the player/client. They are sized for a 10,000x10,000 meter scene and can handle decent sized mountains at the edging (100 Scaling). This is more than enough for almost every design. You can scale the meshes up if you wish. After a certain amount you may need to play with the cloud texture tiling. As with anything it is your visual design that matters....the system is set up for you to adjust this.

Precipitation: You have to make certain Snow (or Rain) is not set to Test Mode. Then when using external scripts to set the Cold and Warm Fronts....you only want to so this if there is a Change. Let me explain. Genesis Weather works on a very efficient 10 second update cycle. Each update it does all what it does....this means reducing the current Front Duration. Once the Front Duration is at zero....the Next update generates a new Front...Warm or Cold. Warm Fronts absorb moisture and Cold Fronts precipitate. If the Humidity is less than the Minimum Required to Precipitate set point a Warm Front will automatically be set IF the Front Duration is less than 10 cycles. This gives a nice hysteresis to fronts and weather dynamics.

gWeatherMaster.cs line 517

Code (CSharp):

1. //If Humidity is Less than minimum configuration then set a Warm Front
2.                     if (fHumidityPercent < fHumidityRequiredToPrecipitate && nFrontDuration < 10)

So....if you want it to Rain or Snow all the time then set the Humidity to what you would like and as often as you like. Then set the Cold Front by setting Cold Front to 1 then Warm Front to 0 ... then set Front Duration to what you want Greater than or Equal to 10 when there is a Change. You may control all of this externally but just a couple things to keep in mind.

The icy snow will fall from +1.5C to -0.1C then the softer snow flakes take over. Rain stops at 0.0C.

I just ran a test here and it is working as expected.

Hope that helps explain things.
Cheers
O