Transform point using localToSceneTransform

[Martin Desruisseaux]

Le 26/07/12 11:23, Kirill.Prazdnikov a écrit :
> So then one class representing en element of R3 space would be enough 
> for me to develop R3 math.
> Probably I do not see advantage of having two classes representing the 
> same ?

I think it is about safety in preventing non-sense operations. We see 
similar situations in lot of cases. In physics for instance, Torque and 
Work both have the same units of measurement (N*m), so mathematically 
they could be added, but units libraries will often use two different 
classes for those two kind of measures precisely for preventing their 
addition.

Same for temperature: multiplying 2°C by a scalar is okay if the 2°C 
value is a temperature interval, but physically non-sense if it is a 
temperature measurement (however multiplying 2°K would be okay). So even 
if we are in the same space, the set of allowed operations depend if the 
numerical value is a position or an interval.

So the issue (as I understand it) is whatever we consider that it is 
user's responsibility to understand what he is doing, or we protect him 
against misuses (either accidental or by misunderstanding).

     Martin