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[Sigma]

This code is from unity default SmoothFollow.js camera script

currentHeight=Mathf.Lerp(currentHeight, wantedHeight, heightDamping * Time.deltaTime);   currentRotation = Quaternion.Euler (0, currentRotationAngle, 0);
transform.position = target.position;
transform.position -= currentRotation * Vector3.forward * distance;

can any one explain this line
             transform.position -= currentRotation * Vector3.forward * distance;
adding a Quaternion (x,y,z,w)(currentRotation) with position(transform.position).

As for as i understand it is something similar to x = x+rcosTheta; but i couldnt visualize whats quaternion role is with W.

Thanks in advance

[BorisTheBrave]

quaternion * vector * scalar = vector (it rotates it, then scales it)
So you are not adding things of different quantities, you are just adding vectors.

[iggie]

I use quaternions interchangeably with rotation matricies. So this just looks like rotate the unit forward vector into the current direction and then move the position along this vector by the distance to travel.

If you start worrying about what 'w' means you will probably waste a lot of time that could be spent coding gameplay, life is much simpler if you treat Quats as useful black-boxes and don't stop to look inside 

[Sigma]

Thanks for the reply. i guessed right.

[slembcke]

life is much simpler if you treat Quats as useful black-boxes and don't stop to look inside 

I disagree, there are a bunch of custom rotation operators that I've written. Trying to get them to work using the trig style operations ended up being a disaster with domain issues and awful performance. That said, I rather enjoyed figuring it out as well.