Software Design Lecture Notes
Fall 2004

Today
-----

1) Project reports / feedback

2) Interaction of OpenGL and Gui

3) Discussion of OO version of teapots.

4) Small amounts of fun


Tomorrow
--------

1) documentation scavenger hunt!

2) more fun


Bottom-up OO design
-------------------

1) start with procedural exercises

   a) look for opportunities to improve interfaces

   b) identify invariants

   c) look for opportunities to improve error-prone semantics


2) grow objects by

   a) grouping related procedures

   b) grouping related data

   c) use object semantics to enforce invariants


3) refactor objects

   a) think of IS-A and HAS-A tradeoffs


4) identify patterns

   a) visitor pattern

   b) bridge pattern


5) look for opportunities to generalize

   a) think in terms of language creation

   b) what's next?



Three ways to vary behavior
---------------------------

1) data-driven

2) object-driven (inheritance)

3) object-driven (reference)



State management
----------------

One aspect of the OO design is that most state is stored
in both OpenGL and in one of my objects:

pro) this makes it easier to organize data logically

pro) object constructors are a natural place to store
     and document default values

pro) we can keep multiple objects of each type and swap
     them in and out

     example: switching among multiple cameras

con) resource use (probably not significant)

con) we take on the burden of maintaining consistency

     example: when we change an object, we usually have to
              invoke setup to make the change effective



Fun with teapots
----------------

Some things you might want to play with in order to get more
familiar with OpenGL:

1) fiddle with parameters to see the effect

   a) fog

   b) positional and directional lights


2) take advantage of the OOness

   a) create more objects

   b) create more cameras and switch among them

   c) play "where's my teapot?!?"


3) play with the object structure

   a) create more teapots and play with their parameters

   b) write additional object types for glutSolidCube or the
      other glut shapes

   c) use Cube to implement an object that draws Rectangles
      (see glScale)

   d) in lab we will learn how to build objects from polygons


4) make an OpenGL world that is also a RemoteObject