Weather (wind, temp, and pressure)

The wind system we have in SL now is certainly nice enough for particle effects and vehicles that don't rely entirely on it for navigation, but I've noticed it also has some serious problems. If you've spent much time in a hot air balloon (or maybe a realistic sailboat if anyone has tried it), you'll see what I mean.

First, it seems more likely than not to drive wind-dependent objects toward the edge of the world. If you're in, let's say, a hot air balloon that only has vertical controls, you should expect to spend up to 10 minutes straight bouncing off the corner of a sim before it pulls you back to at least the center again. If you're very lucky, it won't push you back there too soon. As anyone might imagine, this is really annoying.

Second, wind doesn't seem continuous across sim boundaries. I've had plenty of times when I've moved across from one sim to another and the wind has completely reversed itself instantly at the crossing.

The thing about air is that it's a fluid, a compressible one at that. Wind comes from the way that fluid responds to temperature and pressure. It seems to me that it would make more sense for SL's wind to work based on large pressure systems that cover several sims. If there's a hole in the grid, the wind should blow around it, not through it. It doesn't need to be absolutely precise, just enough that the wind isn't driving us into corners half the time when we choose to let it guide our paths.

So here is what I'm proposing:

1. Give us temperature. llTemp() would be fine for reading it. The heating of any section of a region could be based on the position of the sun, contour of the ground, and color of the terrain. Since terrain textures aren't complicated, I think this could be done without much load on the servers.

2. Give us atmospheric pressure and also let us read it with an LSL function like maybe llAirPressure(). This should mainly be what drives the wind. There wouldn't need to be many sources of pressure to make the weather in SL really interesting.

3. Give us a vertical component to wind based on ground contour, temperature, and pressure (temperature and pressure providing a sense of density). The closer to the ground, the more effect the ground has.

I know there have been other threads asking for things like snow and rain. I fully endorse those ideas and I think my suggestions could make them even more realistic.

My ratings
Priority: 3 (let's face it, there are a hundred other features which are more important)
Practicality: 4-8 (depending on the model)
Coolness: 9 (I could see so much interesting stuff I could do with such a system)

Though more realistic weather would be very nice, I question whether the benefits would outweigh the drawbacks. As it is, very few computational resources are used to generate wind and clouds, and the sun's effect is negligible. The more complex you make things, the more intensive the processes become. To model wind flow based upon barometric pressure, and to determine that air pressure from the position of the sun and the nature of the ground textures would be significantly more complicated than our current system, and most certainly more computationally intense. Of course, the degree of complexity depends entirely on how precise we make these models. With the right model, it might be very simple to do what you've suggested.

However, this is a function which I don't think necessarily needs to be implemented by the Lindens. Whenever I read these suggestions, I wonder whether something could be implemented by us end users without Linden intervention. In this case, I think it would be possible to model some of the things which you've suggested. Maybe have an external server with some sort of climate model on it, which sends this information in-world for subscribers to use. If Cubey wanted to build his planes to take into account this server's wind, he could merely apply a force with the vector supplied by the service. More interestingly, we could even code in things like fronts and storm systems. Other subscribers might have particle systems over their parcels which turn to rain when the weather system suggests that a storm is on the way. It wouldn't be as well integrated as a Linden system would be, but I think it's doable and it would take some of the load off of the sims.

PRO: If motivated, such a system could be implemented much more quickly than LL would.
PRO: Potential for profit and/or massive kudos.
CON: Wind data would have to be less frequent than now, to reduce server load
CON: Potential for complete failure and/or ostracism
CON AIR: Just because

I agree that the priority is low. And I know that the precision of these things will have some impact on the change in server load. I also don't think the precision would need to be very high to make this a serious improvement. I don't think it would create much more load on the servers if it were all done properly. My main reason for wanting changes is just that the wind doesn't always make sense, like how it's most likely to blow you toward holes in the grid. If they redo the system to fix that, they may as well get a list of things to do, put it off until the rest of the game is working pretty well, and do it right.

And I don't think a system made by users would necessarily be better. I don't see how it would be too cool if your wind-propelled craft is going one way and the particle smoke that follows the Linden wind is going the other way.

I could do a global weather system. Until about a month ago I was working on a system of covering the entire SL grid with objects, all starting from a single point, so yeah, wouldn't be that hard. It wouldn't be very realistic, but then again what in SL is?

Edit:
It would follow wind, and clouds, and rain according to cloud density. Easy. But what would be the point? Last time someone offered to make a global weather system (when the grid was 1/5th the size it is now) there was an overwhelming majority of people who DIDN'T want it.

Do you have a link to a thread where someone offered to make this system and a bunch of people said no? I'd be a bit curious to see what some of the responses were. It seems to me that rain and snow could probably be turned off in an option and the change in wind could be ignored by anyone who doesn't care.

As for what the point would be, I want it right now so my hot air balloon stops smacking into corners over half the time. I can think of other uses for it though. With the temperature alone, you could make a car that starts harder when it's cold. You could make ice effects on your land that melt when it gets warm enough and refreeze when it gets cold again. If you really wanted to, you could even dress your avatar to the weather. I don't see what's bad about any of that.

Ok, unless they completely redid the way wind works, the wind would still bump you into corners.

Wanna know why? Build a 'weather balloon' that hovers at a certain distance, is physical, and moves according to wind direction. Much like your balloons that are guided by the wind.

Don't release it yet.

Fly in circles. Big circles. Basically, one giant circle within the sim. Keep doing it. Lots. And lots.

Then land, and release your balloon. Observe, as the balloon...

...moves in circles. Like it's in a tornado.

Yes, that's right. Avatars affect the wind just by moving around. Which is why all wind goes to the edges of the world. Avatars always fly from the 'center' of the world (telehubs) outward. And very rarely the other way around.

Or so I was told by a Linden once. The thread was deleted when the entire scripting forum vanished. (*sigh*)

That said:

Global Weather System Proposition

Moleculor,

I find the argument to which you linked to be very interesting. I had not realized that people were so opposed to bringing such small bits of realism to this world. The concerns over client-side lag are somewhat legitimate, but the rain and snow effects which I've currently seen perform very well. I would like to see someone with a private island place rainclouds or snowclouds over their entire sim, and see what the result is for the client's framerate.

Personally, I would love to have a global weather system for my parcel, and I'm sure that there are others out there who would as well. But I think the effect of such a system is broken of none of your neighbors are using it.

As for the wind issue: I think that avatars should have a much smaller impact on the wind. It seems like the primary source of wind would be the great ocean void beyond, not players rushing about.

The only real problem I see with a weather system of any kind is the fact that we can't make particles collide with anything. It would make -so- much more sense for particles to collide with things, so we didn't have rain coming through our ceilings.

Framerate wouldn't be a problem. I know how to avoid such pitfalls.

As for wind, I'm fairly certain that avatars -do- have a relatively small impact. But considering over 90% of all traffic is "outward", that impact adds up.

Maybe the feature request should be a counter-force from the ocean/edges?

The only intelligent way I can see to do rain in this game is to make it separate from the current particle system. As I stated in my thread about the particle system problems, the system fills up very quickly and particles 700m away can have an impact on the limit. If you're going to make any sort of realistic rain that fills up an entire sim, you're going to need more than 8192 particles at a time to do it. That is, unless the client is ONLY creating the effect very close to the avatar in the direction he or she is looking.

That said, we'd have maybe up to 1024ish particles active at a time for rain or snow and I don't see why it would be so hard to make them collide with objects and disappear. The client already knows where all the objects are in the immediate vicinity and it's not like the particles are going to create any sort of push on them that would need to be calculated. You'd need to have some sort of occlusion system that would keep them from appearing when there's a roof over your head you're not looking at (perhaps this was a problem with getting the old system to work?), but I don't think that's impossible.

And my comment on the thread you posted the link to is, I think the complaints might have been partially based on how the system would likely be implemented (user implementation which you can't turn off) so I can understand the comments. I wouldn't want a system of rain and snow if it couldn't be toggled on each client and I can understand responses like that. On the other hand, if LL implemented a system and it ended up being something you could just turn off on your end, I would see whining about it as pretty dumb.

not like i'm the big expert but a trick i found working with particles is to put more than one particle in your particle. uh, what i mean is make an image to use as a particle that has more than one thing in it, drops, flakes, skulls or whatever. most of the particles i see use that default one and it's terrible for looking like a raindrop. i made a particle for water drops (waterfall spray) that has about 50 drops in it. i use it and zing, it looks like i have 50 times as many particles as i do. same thing for rain. make a particle with five or six drops in it all randomly placed and there ya go. lots of rain with not alot of particles. and make your particles small! the image i mean. when they're flying all around a 16x16 or 32x32 image looks great even when it's blown up huge. they don't need to be big fat images.

I'd like to see ocean currents.

and oceans.

No, just the currents.