Ogre Forums

I am such a lamer when it comes to real analysis : what does that mean :
/** Gets the derived direction vector of the camera, including any
rotation inherited from a node attachment and reflection matrix. */
Vector3 getDerivedDirection(void) const;
https://ogrecave.github.io/ogre/api/13/ ... 4ab37bc1c3
at least I know what's direction vector of a camera but derived ?
what is the variable being differentiated here ?
this function is far from knowing about the potential movement of camera...
wolfram mathworld to the rescue : https://mathworld.wolfram.com/Direction ... ative.html "The directional derivative del _(u)f(x_0,y_0,z_0) is the rate at which the function f(x,y,z) changes at a point (x_0,y_0,z0) in the direction u. It is a vector form of the usual derivative, and can be defined as ..."
So where is the unit vector in this code ? or I don't get something ? because it'getDerivedDirection argument list is void ! >>

In Ogre & OgreNext objects can be attached to scene nodes (which can also be child of parent nodes).

Each node has its own direction. getDerivedDirection() gets you the final combined direction after evaluating all nodes, while getDirection() gets you the local direction relative to the scene node it is attached to.

It's like you're inside a car and you're looking left towards the door window, facing west. But if you rotate the car 90°, now you're still looking to the car's left towards the door window (getDirection), but you're now facing south (getDerivedDirection).

EDIT: The wolfram article talks about mathematical derivatives, which has nothing to do with "getDerivedDirection()" in this context. In math, derived is not the same as derivative.

sorry, sometimes my English amuses me .