JRobots

JRobots is a browser-based programming battle arena similar to CRobots but written in Java.

Players can program their robots using a custom "mini-language" and watch them fight inside a deterministic (the same input always produce the same result) simulation engine.

Note: JRobots is still in development and still missing the main functionalities.

Tech Stack

• Java 12 +
• Spring Boot
  • Spring Web
  • SpringBoot DevTools
  • Lombok (optional)
• Maven

Project structure

JRobots/
├── backend/
├── frontend/
├── pom.xml
├── README.md
└── .gitignore

Backend package structure

JRobots/
└── backend/
    ├── api/   # REST API endpoints
    ├── bots/   # Built-in robots for testing
    ├── config/   # Currently EMPTY
    ├── dsl/   # Currently EMPTY
    ├── engine/   # Simulation engine (robots, bullets, physics)
    └── replay/   # Replay data structures (snapshots + events)

Current features

• Robots can move and turn.
• Robots can fire bullets.
• Bullet have physics and collision detection.
• Energy-based damage system.
• Match result (WIN / DRAW).
• Replay generation.
• Event timeline per tick.
• Robots can scan the battlefield to find the opponent.

Design

The game runs at a certain number of ticks per seconds during which a series of tasks are completed in order:

1. Engine resets all the actions.
2. Controllers request actions.
3. Spawn bullets if fire is requested by a robot.
4. Apply robot physics.
5. Apply bullet physics.
6. Detect collision between bullets and robots.
7. Remove dead bullets.
8. Generate events.
9. Record snapshot.

Replay system

Every match generates a replay containing the full history of the simulation by saving a snapshot at each tick.

A snapshot looks like this:

{
  "tick": 42,
  "robots": [
    { "id": 1, "x": 150.0, "y": 320.0, "energy": 80.0},
    { "id": 2, "x": 600.0, "y": 310.0, "energy": 10.0}
  ],
  "bullets": [
    { "id": 12, "ownerId": 1, "x": 420.0, "y": 305.0}
  ],
  "events": [
    { "type": "FIRE", "robotId": 1, "bulletId": 12 },
    { "type": "HIT", "bulletId": 12, "ownerId": 1, "targetRobotId": 2, "damage": 10 },
    { "type": "DEATH", "robotId": 2 },
    { "type": "END", "result": "WIN", "winnerId": 1 }
  ]
}

Events

Events are important gameplay actions that happen during a tick.

Event	Description
FIRE	A robot fired a bullet
HIT	A bullet hit a robot
DEATH	A robot’s energy reached zero
END	The match ended (WIN or DRAW)