Help Vector4 Usage For Particle Positon and Velocity

[GrimCaplan]

Hello again!

I was wondering if someone could shed some light on what the purpose/function of the 'w' value in the vector4 used for both position and velocity for particles?

For example:

Code:

// Calculate and apply spring force:
                    Vector4 position = solver.positions[pickArgs.particleIndex];
                    Vector4 velocity = solver.velocities[pickArgs.particleIndex];

Is it used like a quaternion? I didn't just want to assume/guess so I figured I'd ask. I checked out the definition ObiNativeVector4List but it's not really immediately obvious to me. I might just be developmentally challenged.

Thanks in advance.