1. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 Developing a Simple Game-Themed Application Kelvin Sung Computing and Software Systems University of Washington, Bothell

2. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 Goals Design and implement a simple “game” Practice what we have learned so far Separation of logic and graphical interaction Let’s work in groups (3 or 4) …

3. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 Approach Goal:  A detailed design for implementation in 3 hours Tasks: (in 90 minutes)  20 min: Game idea (be SIMPLE! )  10 min: Relative sizes and look (coordinate system)  10 min: Main object look/behavior (class)  10 min: Support object look/behavior (class)  20 min: User and Object interaction (in UpdateWorld)

4. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 Game Idea Logic vs Interactive Graphics  Today: concentrate on Interactive Graphics Avoid in-game “AI” (or smart game)  E.g.: tricky to implement:  User control Object A  Game controls Object B to follows automatically  E.g.: Easy to implement  Use control Object A  Game controls Object B _RANDOMLY_  Test for Object A and B interesection

5. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 Choose A ‘Game’ Type Graphical Picture  Nothing moves  No user interaction Animation / Visualization  A sequence of pre-defined movements  No user interaction Interactive Game  Movement of objects responds to user interaction

6. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 ‘Game’ Type Examples Graphical picture:  Response to simple user commands (e.g., draw a picture responding to a button push)  Draw a histogram Animation / visualization / simulation:  Dropping a ball: conditions ensuring the ball bounces when it reaches the ground, implement a mathematical equation  Visualization of random samples Interactive  Initial object setup  One/multiple objects under user control  Update and test for object intersection in UpdateWorld

7. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 Finding Ideas For ‘Game’ Type Card Games Board Games:  Snakes and Ladders Snakes and Ladders  Reversi Reversi Anything you’ve found fun (or not)  Breaking Bubbles Breaking Bubbles  Alphabet Hero Alphabet Hero

8. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 Designing A Game Draw pictures/ideas Play the “game” on paper during design.  Design the interface to the technical topic area  Remember, complicated in-game AI is tricky to implement!

9. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 Implementation Guide 4 major pieces to implementation:  The World  Hero Object  Support Object  Interaction between objects

10. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 The World Relative size:  Window size vs. Object size Continuous Coordinate  E.g., The BlockBreak Game Discrete Coordinate  E.g., Reversi (position (1.5,1.5) is illegal) In InitializeWorld()!!

11. XNA Game-Themed Workshop, FDG Pre-Conference Workshop, April 25, 2009 The Hero/Support Object Look: Constructor()  Size, color, texture Behavior: Update()  User control behavior (e.g., user move paddle)  Automatic behavior (e.g., gradually slow down when user is not moving)  Automatic behavior is trickier to implement! Interaction: Interact()  Interaction with other (Support) objects