Wind in Second Life
From SecondSailing
Yes, there is wind in Second Life.
Of course, it's all just a bunch of electrons going through fancy circuits.
But on the other hand, isn't wind in RL also not only a bunch of fancy molecules moving on strange paths through our world?
Contents |
There are several wind concepts (2 or three, depending on how you count) that boats use in SL.
SL wind
If you look around in Second Life you probably have seen flags and trees moving. This is initiated by a phenomenon called SL wind. It is there in every sim and scripts can query it. So boats can use it to sail the seas of second life. Descriptions of how wind in second life works are rare. Here is one of them: LSL Wiki about weather
One fact about SL winds is, that they change often and are much more erratic then usual RL winds. It's a challenge to sail them. You probably don't want to do that.
Querying SL Wind
Unlike the wind conditions generated by wind setters or the boats themselves, SL Wind is a stable fluids simulation that runs on the Second Life servers. Every region has this basic type of wind. You can find out the local SL Wind speed by doing the following:
- Rez a prim and name it.
- Add a new script to the prim's content and replace the script's content with the following:
default
{
state_entry()
{
llSay(0, "Touch me for current sl wind speed.");
}
touch_start(integer total_number)
{
vector wind = llWind(<0,0,0>);
llSay(0,"Wind speed: " + (string)llVecMag(wind) + " m/s");
}
}
- Save the script and close the script editor.
- When touched, the prim will report the current SL Wind speed at the prim's location in meters per second.
Skipper wind
As wind is just an input into the script, that governs the boat's behavior it is easy to make the boat "generate" it's own wind. All boats have a way to set these wind parameters, usually you find parameters for wind direction, wind speed and parameters that let the skipper wind vary around these given values.
This is the easiest and most comfortable way to sail any waters in SL. But it has one disadvantage. As every skipper can set it's own wind for his boat, two boats that meet may not have the same wind settings and usually don't. Not a big deal while you do leisure sailing this is a real problem when you do hotlaps or fleet races.
For this reason another wind concept exists in SL called "race wind"
Race wind
While using race wind the boat gets it's parameters from a special device called a Wind Setter. This devices sends its parameter to all boats in a racing fleet thus making sure they all use the same settings. A closer look will reveal that this is basically the same concept like "skipper wind". The only difference is that not the input from the skipper controls the wind settings but the input from the wind setter.
Additionally most boats work together with the Start Line which sends a special command to each boat, once the the line is crossed. This command "locks" the wind settings until the line is crossed again. This will prevent that a boat uses other wind settings that it might pass when sailing the race course.
Wind parameters and wind
The parameters you can set are "average wind direction", "average wind speed", "directional deviation", "speed variation", "variation speed". But how is this converted into the wind setting currently used by the boat?
Angles in Navigation vs. Angles in Geometry
- When navigating in Second Life, it is important to keep the following in mind:
 |
In navigation, headings are derived from the four cardinal directions or 32 compass points, running clockwise with North as the reference point. Thus, North-West equals 315 degrees. |
 | In geometry, angles are measured from the x-axis of the Cartesian plane ("East"), increasing counterclockwise. Geometry allows for both positive (counterclockwise) and negative (clockwise) angles, whereas negative bearings are not used in navigation. |
 |
Second Life uses (positive) geometric angles, with East as the reference point running counterclockwise. Thus, "North" is 90°, "West" is 180°, "South" is 270°; A compass heading of 315° ("North-West") equals 135°. |
 |
A Wind Setter operates using geometric angles and most boats show wind directions and headings based on geometric angles, not compass angles. This can be confusing at times, especially with south-westerly headings or wind directions (compass and geometry angles will look similar). |
