descentinel

Support app for the board game Descent v1 that keeps watch over a physical game in progress.

1. The app consists of various backend services:
   • monitor: always watching...
   • detect_card: which card am I holding in the camera?
   • broadcast: a web server for backend-frontend communication
   • presentation: a web frontend
2. All backend services are connected to rabbitmq pub/sub channels
3. The entire app runs on a small device (Raspberry Pi)

Interplay of backend services

Here is a visual display of the queues going out an into various services.

graph TD;
    classDef service fill:#EFC403
    classDef queue fill:#032EEF,color:#eee
    services[[services_look_like_this]]:::service
    queues([queues_look_like_this]):::queue

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graph TD;
    classDef service fill:#EFC403
    classDef queue fill:#032EEF,color:#eee

    Q_GAME_ROOM_FEED([Q_GAME_ROOM_FEED]):::queue
    Q_DETECTED_OL_CARDS([Q_DETECTED_OL_CARDS]):::queue
    Q_SHORT_LOG([Q_SHORT_LOG]):::queue

    monitor[[monitor]]:::service
    monitor-->Q_GAME_ROOM_FEED;
    monitor-->Q_SHORT_LOG;

    detect_card[[detect_card]]:::service
    Q_GAME_ROOM_FEED-->detect_card;
    detect_card-->Q_DETECTED_OL_CARDS;
    detect_card-->Q_SHORT_LOG;

    broadcast[[broadcast]]:::service
    Q_GAME_ROOM_FEED-->broadcast;
    Q_SHORT_LOG-->broadcast;
    Q_DETECTED_OL_CARDS-->broadcast;

    presentation((presentation/frontend))
    style presentation fill:#EF03A5,color:#eee
    Q_GAME_ROOM_FEED-->presentation;
    Q_DETECTED_OL_CARDS-->presentation;
    Q_SHORT_LOG-->presentation;

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monitor: stream the game pieces as images

What?

• A continuous video feed from a small camera is chunked into still images for downstream services to digest.

Why?

• This is the eye of the app. It's the one source of information for any component of descentinel.

How?

• Capture video signal and chop it into still images in pre-defined time intervals using rust.

detect_card: recognize various cards

What?

• An image of a card with a QR code is given to this service. If the QR code is detected correctly, the card is identified by the content of the QR.

Why?

• Other services may use the context information to display more infos about the card. Examples may be translations from other languages or information from http://www.descentinthedark.com.
• Ultimately we have a (ro)bot playing with us and using and referencing the physical components.

How?

• rust

broadcast: provide GET for frontends

What?

• Any content produced by a backend service and pushed to some rabbitmq queue is published over a GET.

Why?

• Frontend technology should be decoupled from messaging in the backend, hence a dedicated web server.

How?

• rust
• warp
• server-sent events (SSE)

presentation: frontend for the browser

What?

• server-side rendering of updates interesting for user

Why?

• Game information should be viewable on any device.

How?

• leptos CSR

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Descent: Journeys in the Dark is Copyright © Fantasy Flight Games. All rights reserved.