Wind Direction?

[Capsup]

Well, I'm making a sail that will act like a sail in real life would, my problem is, how would I check if my sail is turning agaisnt the wind direction? At the moment, I'm just generating a random vector, multiplying it by the models mass, and then phys.ApplyForceCenter. It works great, except, that the boat will keep spinning around.

Code that I use to apply the force:

[lua]
function ENT:Think()
if( nextthink < CurTime() ) then
nextthink = CurTime() + 1;
vector = GetGlobalVector( "WindVelocity" );
end
if( self.Entity:WaterLevel() == 0 ) then
local phys = self.Entity:GetPhysicsObject()
if phys:IsValid() then
phys:ApplyForceCenter( ( mass * vector ) );
print( "Min: " .. tostring( mass * vector ) );
end
end
end
[/lua]

and creating the vector is just this:

[lua]
SetGlobalVector( "WindVelocity", Vector( math.random( -10, 10 ), math.random( -10, 10 ), 0 ) );
[/lua]

Any help appreciated.

[Crazy Quebec]

There is no "Wind direction" in the game so you'll have to set your own.

[Capsup]

Uh, that was what I meant? :O

I need some help with checking if my sail entity is turning agaisnt the direction from where the wind is. That's the only thing I need some help with.

[Nev]

You'd do it with some simple vector math..

[lua]
local wind_normal = GetGlobalVector( "WindVelocity" ):GetNormal( );
local sail_normal = entity:GetForward( );
local dot = wind_normal:Dot( sail_normal );
[/lua]

Dot would be 1 if the wind normal is pointing in the same direction as sail normal, 0 if they are perpendicular and -1 if pointing the opposite direction.

[Capsup]

Thanks alot for that Nevec!