With Johan away to E3 we didnít 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.
Letís move swiftly along to the subject of todayís 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 didnít mean we couldnít 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 doesnít mean we canít 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.