FlappyBirdAI

Game Mechanics & Physics

This project uses Phaser 3, a powerful 2D game framework, to handle the game loop, rendering, and physics.

Physics System

We use Phaser’s Arcade Physics system, which is lightweight and perfect for simple 2D games like Flappy Bird.

Collision Detection

Collision detection is handled using AABB (Axis-Aligned Bounding Box) logic. The game checks for overlaps between the bird’s bounding box and other objects.

graph TD
    A[Game Loop] --> B{Check Collisions}
    B -->|Bird vs Pipe| C[Game Over]
    B -->|Bird vs Ground| C
    B -->|Bird vs Ceiling| C
    B -->|Bird vs ScoreTrigger| D[Increment Score]

• Bird: A dynamic body affected by gravity (1000).
• Pipes: Kinematic bodies that move left (velocity.x = -200) but are not affected by gravity.
• Ground: A static body that the bird can collide with.

The Game Loop

The game runs at approximately 60 frames per second (FPS). However, for AI training, we implement Frame Skipping.

Frame Skipping

To speed up training and stabilize inputs, the AI doesn’t make a decision every single frame.

1. Skip 5 frames: The game physics update normally, but the AI does nothing (repeats previous action or idles).
2. Act on 6th frame: The AI observes the state, calculates a reward, and chooses an action.

This reduces the computational load and prevents the AI from “jittering” by reacting too fast to minor changes.

Game Objects

Object	Description	Physics Properties
Bird	The player/agent	Gravity: Y, Velocity: X/Y
Pipe	Obstacle	Velocity: X (Left), Immovable
Score Trigger	Invisible zone between pipes	Velocity: X (Left), Sensor (No collision response)

This site is open source. Improve this page.