Get signed rover speed

[lo-fi]

Evening.

I'm trying to work out how to get the speed of a rover, though signed negative to indicate when it's travelling backwards. Is there an available method to do this that I've missed? I've just spent and hour hunting through the stuff that comes up in the VS inspector for this.vessel., but come up blank so far.

Thanks, as ever

[Greys]

That's going to be hard due to how symmetry works, but I imagine if you could decide on a forward vector for the wheel and have it be uniform across the vessel and over time, then you could just compare the vessel's movement to that vector to determine the signage and apply that to the value you get off the wheelcollider.

[Dunbaratu]

The velocity of the vessel will be a vector, rather than a scalar, making the meaning of "negative direction" sort of meaningless. It's more like "velocity in this 3-D direction."

To get the surface-relative velocity instead of the orbit-relative velocity, use Vessel.GetSrfVelocity().

To get a unit vector pointing in the direction the vessel is pointed, do one of these two things:

roverFrontUnit = Vessel.GetTransform().rotation * V(0,0,1) // Gives a unit vector pointing "up to the nosecone" of a rocket built in the VAB.

roverFrontUnit = Vessel.GetTransform().rotation * V(1,0,0) // Gives a unit vector pointing "ahead to the front" of a vehicle built in the SPH.

Which way is correct depends on which way you built the rover orientation.

(This is from my memory and I might have it wrong which unit vector to start from. It might be the Y axis not the X axis. Please experiment and try).

Once you have such a unit vector, you can dot-product the vector with the surface velocity to get the component of the surface velocity that is aimed forward (positive number) or backward (negative number).

[lo-fi]

Thanks guys. Two methods to try - I'll let you know how I get on

[lo-fi]

For future reference, this works perfectly:

//C#
            Vector3 roverForward = this.vessel.GetTransform().rotation * new Vector3(0,1,0); //y is forward direction for SPH built craft
            Vector3 travelVector = this.vessel.GetSrfVelocity();
            float travelDirection = Vector3.Dot(roverForward, travelVector);

I never thought I'd find an actual use for dot products

Thanks again!