Week 3

Week 3:

• GoF design pattern presentations
• Transformations and matrices in OpenGL (Part 2):
  • Representing hierarchies (see Technical Context: Scenegraphs)
  • Relative and absolute positioning
• Design patterns introduction:
  • Software as a collection of building blocks
  • Efficiency, ease-of-use and other architectural considerations
• Designing graphics software:
  • Separation of concerns
  • Setup-Update-Draw (see Technical Context: main() to Processing)
  • Model-View-Controller
  • Nodes, networks, scenes and graphs
• Towards an API: (see below)

In-class Exercise:
Please form groups of two or three students. With your group, discuss the features that you would like to include in your scenegraph API. You can start with whiteboarding, prototyping or whatever method works best for your team. Ultimately, during this class exercise, you should arrive at a sketch of your header files - an outline of the classes and functions that will comprise your system. The actual implementation will come later. You’ll likely want to include features that relate to subjects we haven’t studied yet: cameras, lights, etc. This is a common predicament in software architecture. Take a stab at how these features might fit into your API and you can refine them later as you learn the underlying details. As a group, you might want to start by making some of the big picture decisions, for example - do you want to focus on 2D, 3D or both?

Homework:
With your group, please implement the scenegraph API you started in class.
Implementations will be evaluated on the following:

• Correctness: Proper memory management, separation of concerns, etc
• Ease-of-use: Consistent naming schemas / data structures, comments, etc
• Depth: Broad feature support and configurability

Depth and ease-of-use often work against each other. Try to achieve a balance between these two. If you can’t, then really overcompensate with one or the other. A less feature-rich API should be extremely easy to use - think iOS vs Android.

Please be prepared to present this work in two weeks. In your final implementation, please be sure to include a "sample project" that demonstrates basic usage of your API in a graphics application.