Yarn's Story

Team Members and Contributions:

• Steven Louie : Task Group 1 (refer to Design Overview diagram below)
• Mohit Patel: Task Group 4
• Yueqiao Zhang: Task Group 2, graphic design and video making
• Danqing Zhao: Task Group 3
• Yu Zhao: Task Group 0, documentation, diagram preparation

About Yarn's Story: https://youtu.be/aoWMlE4MoLE

Once upon a time, there is a naughty dog named Yarn. He loves finding balls in his cozy home and hates dog bomb.

• When Yarn hits a ball, player gets 10 scores and another ball is created randomly in the room.
• When Yarn hits a bomb, player gets -10 scores and Yarn’s speed get increased and another Bomb is created randomly in the room.
• Magic States (SPEEDUP, SPEEDDOWN, INVINCIBLE) are randomly attached to ball and bomb, which cause temporary state change on Yarn for 2 seconds.
• There are walls/obstacle in the room. When Yarn hits a wall or the border of the room, game ends.

Start Page

Game Page:

Yarn gains a STAR State

Yarn gains SPEEDDOWN State

After 2s, State disappear

Score Board:

Design Overview:

All main component and basic interactions between components are shown above. Four design pattern are implemented (Decorator, State, Observer, Composite). The whole project is split into 5 task groups, each team member focusing on one task group.

• Task Group 0 (Yu): MagicState and MagicState Manager
• Task Group 1 (Steven): Ball and Bomb (including decorator pattern and Touch Subject implementation)
• Task Group 2 (Yueqiao): Score Board (Composite Pattern) and Game entry/end World
• Task Group 3 (Danqing): Display Components (Status, Speed, Score) and Touch Observer
• Task Group 4 (Mohit): Game World (Room) and Yarn, integration of all the components of the game

Key Design Features:

1. Decorator Pattern

Decorator Pattern allows us to add reponsibilities to Ball and Bomb objects dynamically, a random MagicState effect is added to them. Although now our current demo is pretty simple, this pattern could help us gain more flexiblity when we try to extend/add more complex reponsibilites to Ball and Bomb. And those responsibilities are also easy to remove. In our case, due to constraint of Greenfoot, we also use a Observer pattern to associated with Decorator pattern to handle touching event.

2. State Pattern

State Pattern is used to allow an Dog Object to alter its behavior when its magic state changes. The state transition is triggered by either touching a PowerUp (ball/bomb) with Magic State or timer (reset State). Instead of conditional or case statements, State Patter helps us to keep code structure clear and flexible for adding any more Magic State.

3. Observer Pattern

Observer Pattern let us avoid tight coupling between Item(Ball, Bomb,Wall and even PowerUp) and all kinds of DisplayComponents. We could vary subject and observers independently or add more observers anytime without modified current observers. And it also helps increasing our code reusibility.

4. Composite Pattern

An abstract class ScoreBoardComponent represents both primitive leaf classes (Banner, Title, Background, etc.) and their containers (ScoreBoardComposite). Clients can treat composite and leaf objects uniformly without writing a complex tag-and-case-statement style function. Thanks to composite pattern, now it is easy to add a new component to work automatically with existing client code.

Agile (Agile meeting video link: https://youtu.be/dK3pBHE5QsE)