🚀 go-pugleaf

The problem is the following:

consider a basic graphics class, called 'point3d' encapsulating the concept of
a 3D-point in a coordinate-system. Mind you, the coordinate system is
important, every point has one. A number of operations are defined on those
points, like multiplication (inproduct), adding (translation) etc. etc.
Everytime two points are incompatible, ie. are in different coordinatesystem,
one of the two is forced in the coordinatesystem by a coordinate
transformation.

Now, for efficiency reasons, the check whether points are in the same
coordinatesystem needs to be removed, as it turns out that most of the time
points are already in the same coordinatesystem, hence testing is not needed.

Two approaches can now be taken:

1. The original 3-dimensional point in coordinatesystem concept is a special
   case of a normal 3-dimensional point:

   class point_3d
   {
    // baseclass

    ... operations ...

   };

   class point_3d_with_coordinate_system
	: public point_3d
   {
     // subclass
   };

   additional advantage:

   all code for point_3d_with_coordinate_system is very straightforward:

   point_3d_wc::function(point_3d& point2)

   if (point1 not in same coordinate system as point 2)
     force point2 in same coordinate system as point1

   execute equivalent code in baseclass (as coordinate systems are the same)


2. The 3 dimensional point without checks for coordinate systems is a special
   case of the normal case.

   class point_3d_with_coordinate_system
   {
     // different baseclass
   };

   class point_3d_with_no_coordinate_system_check
	: public point_3d_with_coordinate_system

   obvious disadvantage:

   all code from the base-class needs to be duplicated (as the code from
   the baseclass contains the check for coordinate systems).

Any and all opinions from the net appreciated

-- 
+--- Ronald van Loon ---+ 
|  (rvloon@cv.ruu.nl)   | 
|  3DCV Group, Utrecht  |
+--- The Netherlands ---+ This part of .signature intentionally left blank.