class position
{
public:
int x,y,z;
};

class human:public position
{
public:
int height, width;
};

class car:public position
{
public:
int speed;
};

void setposition(position * obj)
{
obj->x = 1;
}

...
human * lol1 = new human;
setposition(lol1);
delete lol1;
car * lol2 = new car;
setposition(lol2);
delete lol2;
...

class CVector3d
{
...
};

class CNode
{
protected:
CVector3d Position;
CVector3d Rotation;
CVector3d Scale;
...
public:
...
};

class CCar:public CNode
{
...
};

class CHuman:public CHuman
{
...
};