comparing vectors [solved]

I have set my other problem aside for the time being, and immediately run into another problem.

I’ll try to give enough background information this time:
I’m making a simple rollerblading racing style game, using an XBOX360 controller for input. I’m working on the motion system right now, and have run into a problem with friction along a local axis (wheels roll forwards, but not sideways)
I believe there used to be a friction setting for this, but I think it doesn’t work in bullet.

I’ve managed to use a formula to get the amount of motion along the X axis as a vector in X Y Z format (as opposed to polar coordinates, not sure if this is useful information but I’ll include it in case it is), and I can use the Pythagorean theorem to get it’s magnitude, and apply that as force along the X axis. It works fine, except the pythagorean theorem removes the sign, so friction slows it down if the X velocity is leftwards, but accelerates it if the velocity is rightwards. (that is, the force is always applied in the same local direction, regardless of whether the X velocity vector is facing left or right)

so we get to the request:
how can I tell if two vectors that lie along the same line are pointing the same or opposite directions? if it helps, one vector always has a magnitude of 1 (it being the X axis as taken from the orientation matrix)

[edit] well, I managed to fix the problem all by myself (ego ++)

To access the friction settings you need to add a material to the object, then under the material tab, click dyn/dynamic and you will see the friction slider.

I had tried it a while back and thought it did work?

Have to research more on the vector direction…

no, the friction settings I was talking about were right above the bounds field in the game engine properties window. they let you set a different amount of friction along each axis

Yeah I know the ones, but it is my understanding they moved them to the materials windows… I dont know, maybe Im confused, but the wiki said thats where they are now in the newer versions???

You said you solved the vector thing? What was the answer. When you have the time of course.

Im sorry I forgot all about this. I was going to search the net for you…

And Ive got about 7 stary cats/kittens I am trying to care for, so I have a few to spare for stupid question… catching them (wild) spaying and nuetering… its tuff, they fight back.

I simply realized that any given component of a vector (say, X) would have the opposite sign of the other if they were pointing opposite directions, since both vectors start at the origin. it’s a simple comparison after that.

thanks for trying to help nonetheless, I appreciate the effort.