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King

Part Time Game Designer
11 Badges
Dec 7, 2001
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  • Crusader Kings II
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  • Hearts of Iron II: Beta
  • Victoria 2 Beta
With Johan away to E3 we didn’t want to leave you all with a total information blackout so I have been drafted to fill the breach on the dev diary front. For those of you who have no idea who I am, I am Chris King and I am one of the designers of Hearts of Iron 3.

Let’s move swiftly along to the subject of today’s dev diary, the weather system. If you look at weather forecasting organisations, they use huge super computers to try and predict the weather and have been known to be slightly wrong on occasion. A highly detailed exact weather model was going to be beyond us, but that didn’t mean we couldn’t improve on our current province based, roll a dice model.

So we went off and spent a couple of days becomes experts in Meteorology (feel the power of the Wikipedia!) and began to build up our weather model. The Weather in a province is constructed from three basic building blocks, pressure temperature and humidity. Pressure and Temperature are province based properties. We actually have a mean temperature map, this is then modified by time of year to give a desired temperature for the province, it further fluctuates around this based on local factors. Pressure works in a similar way, but we will come back to it later. Humidity rises over things like water (especially during high temperatures) and then falls when it rains.

So far pretty basic stuff. However this allows us to create two further parts to our weather system, the overhead and ground conditions. As humidity rises and/or temperature falls the overhead conditions will change from clear to overcast and then to rain. If it is cold then you get snow. If the winds are high and it is raining you get a storm and if it is snowing a blizzard. While on the ground if it is cold then you get Frozen Conditions. If it is raining enough or if the ground has ceased to be frozen you have a chance of Mud (modified by local infrastructure).

So far so good, but we could of done all of this with a simple province based system and odds. However this is where air pressure and a bit of research comes in useful. If you take Western Europe as an example, low pressure appears around Iceland and moves east. There is a permanent area of high pressure centred around the Azores which pushes the low pressure systems along their familiar track. Hearts of Iron 3 is very similar in this regard. The area around the Azores is defined as high pressure which radiates out, while Iceland will generate low pressure that tracks into Europe and is repelled by areas of high pressure. Low pressure systems pickup their local weather and move it in weather fronts. What you end up with is bands of weather moving around the globe bringing things like rain and snow.

Now as I said at the top of this dairy a precise weather system is going to be beyond us, but it doesn’t mean we can’t create a system with a nice touch of reality. In our case you will be able to see the weather fronts moving and this feeds into to your strategy. You are thinking about invading France as Germany, but when? Well it is raining over Germany at the moment, but you can see that the weather coming out of the west is clear. The answer is soon.

To show the shocking outcomes that our new weather system produces, here are some screenshots of rain coming to Scotland.

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Nice to see the weather system working!
 
Very nice indeed!
 
Who thought weather could be so fascinating. Nice one King, thanks for another good diary. A question though, will we be able to see a forecast of the next days weather (an estimate from the AI, just like the weather guys on TV) or will we have to use our own keen senses to spot weather patterns?

Looking forward to release more and more.
 
Who thought weather could be so fascinating. Nice one King, thanks for another good diary. A question though, will we be able to see a forecast of the next days weather (an estimate from the AI, just like the weather guys on TV) or will we have to use our own keen senses to spot weather patterns?

Looking forward to release more and more.

No it is up to your keen senses at the moment.
 
Wow, amazing! Will there be event-like weather for.. lets say Barbarossa or is it left for chance?

It's all up to chance, it makes sure each game is different. One game the weather might be fine and clear allowing you chance to move early. Another year you might be delayed even longer. No game is the same.
 
How big will the impact of the weather be on for example ground units, but also naval and air warfare? Will it be impossible to conduct air missions in heavy storm, blizzard etc?
 
No it is up to your keen senses at the moment.

Would it simply be possible to have arrows on the clouds and such (like on the sprited and counters) so that we have some idea of which way the weather is moving?
 
Incredible! :)

I saw some of this (a "cold front") on one of the IGN screenies but thought it was made up. I am impressed how a little research and a good and easy model can come handy!
 
Sounds like an awsome feature, especially when you aren't expecting something like this.

How detailed is the weather system outside Europe? Do we get monsoon seasons in SE Asia for example?

Weather was, IIRC, a pretty important consideration for Japan when it decided to invade Malaysa and NEI in december.
 
Sounds like an awsome feature, especially when you aren't expecting something like this.

How detailed is the weather system outside Europe? Do we get monsoon seasons in SE Asia for example?

Weather was, IIRC, a pretty important consideration for Japan when it decided to invade Malaysa and NEI in december.


We have low and high pressure system scattered all over the globe and we are constantly tweaking them to give better and better results.
 
How moddable are parameters of the weather system?

Can I create my own version of climate, say, with extreme conditions like super high wind speeds, common tornados and such?

There are over 20 seperate paramaters you can play around with for weather. All stored in a plain text file.