Johnny Reborn

Johnny Reborn is an open source engine for the classic Johnny Castaway screen saver, developed by Dynamix for Windows 3.x and published by Sierra, back in 1992.

It is written in C and has been refactored to use platform-native APIs instead of SDL2, providing better integration with each operating system.

• macOS: Uses Cocoa for graphics and CoreAudio for sound
• Linux: Uses X11 for graphics and ALSA for sound
• Windows: Uses Win32 API for graphics and WASAPI for sound
• Web: Uses HTML5 Canvas and Web Audio API (via Emscripten)

For the screen saver to work, you'll need the three data files from the original software: RESOURCE.MAP, RESOURCE.001 and SCRANTIC.SCR and save it under a data folder in the root directory.

Use extract_sound to dump the audio files from SCRANTIC.SCR file.

cd tools

make -f Makefile.sound

./extract_sound

# Install Xcode Command Line Tools
xcode-select --install

# Install CMake (via Homebrew)
brew install cmake

sudo apt-get update
sudo apt-get install build-essential cmake
sudo apt-get install libx11-dev libasound2-dev

• Install Visual Studio 2019 or later with C++ support
• Install CMake from https://cmake.org/download/
• Or use MinGW-w64 with CMake

# Install Emscripten SDK
git clone https://github.com/emscripten-core/emsdk.git
cd emsdk
./emsdk install latest
./emsdk activate latest
source ./emsdk_env.sh

# Create build directory
mkdir build
cd build

# Configure
cmake ..

# Build
cmake --build .

# Run
./jc_reborn

cmake -DCMAKE_BUILD_TYPE=Release ..
cmake --build .

# Make sure Emscripten is activated
source /path/to/emsdk/emsdk_env.sh

# Create build directory
mkdir build-web
cd build-web

# Configure with Emscripten
emcmake cmake ..

# Build
cmake --build .

# Serve locally
python3 -m http.server 8000

# Open browser to http://localhost:8000/jc_reborn.html

By default, the engine runs full screen and plays the life of Johnny on his island, as the original did.

If you're curious about how the engine works, you may type jc_reborn help and see the different options available. Feel free to try them and explore the inner workings of Screen Antics! Then open your browser and go to http://localhost:8081

By default, the engine runs full screen and plays the life of Johnny on his island, as the original did.

But, if you're curious about how the engine works, you may type jc_reborn help and see the different options available. Feel free to try them and explore the inner workings of Screen Antics !

Currently, Johnny reborn is in "work in progress" state. Even so, as of January 2020, every scene works with only some inaccuracies here and there.

That means that the engine globally works in an acceptable way, but more needs to be done to fully understand a number of details and faithfully reproduce the behaviour of the original engine.

Some great work was already made by Hans Milling for "Johnny Castaway Open Source" (JCOS), back in 2015. This includes:

• the parsing and decoding of all the data files
• the understanding of many instructions which constitute TTM and ADS scripts

What Johnny Reborn brings is:

• the understanding of nearly every TTM and ADS instruction, and their parameters
• the algorithm for Johnny to transitionnaly walk from scene to scene was implemented. Accuracy is not bad though not perfect.
• the same can be said about the algorithm which randomly chooses scenes to be played.
• as well as the algorithm which draws the island at a random place, clouds, etc.
• all the work was made by observing the behaviour of the original software and trying to reproduce it as accurately as possible. For a better result, a complete disassembly of the original exe may be necessary - but wasn't done to this point.

I never would have been able to write Johnny Reborn without, directly or indirectly, all the people listed below. Many thanks to them.

• Hans Milling aka nivs1978, author of the JCOS project - my main source of info for my first lines of the Johnny Reborn code
  • https://github.com/nivs1978/Johnny-Castaway-Open-Source
  • http://nivs.dk/jc/
• Alexandre Fontoura aka xesf, author of castaway project - similar to Johnny Reborn, but in Javascript
  • https://github.com/xesf/castaway
  • https://castaway.xesf.net/viewer/
• The Sierra Chest website, which has a nice section about Johnny Castaway, with many screenshots and video captures. Those turned out to be quite helpful:
  • http://sierrachest.com/index.php?a=games&id=255&title=johnny-castaway

Hans Milling thanks a number of people for giving him (or helping him find) some info about the original engine. They should not be forgotten, and I thank them - indirectly - as well:

• Jeff Tunnel - For helping getting in contact with some of the original developers
• Kevin and Liam Ryan - Assisting with information about the resource files
• Jaap - Helping in finding the format of the resource files
• Gregori - Assisting with the Lempel-Ziv decompression
• Guido - The author of the xBaK project that led to understanding the TTM and ADS commands.