A complete decompilation of Retro Engine v4 and the menus from Sonic 1 and 2 (2013).

This project is a fork of RSDKv4, which was used to develop the mobile remakes of Sonic 1 and 2 (2013) and aims to improve many already existing functions and add a big variety of new ones

LIST OF THE NEW FEATURES & CHANGES (A MORE DETAILED CHANGELOG WILL BE PROVIDED SOON)

• SteamAPI has been implemented. If you own Sonic Origins on Steam, Origins features will be enabled and if you own Sonic Origins Plus you can play as Amy! (can be toggled, see here)
• Custom Discord RPC has been added (I'll probably make a guide on how it works, no promises though.) You'll have to make your own Discord Application and add your own art. For the images, links also works. The new functions include:
  • SetPresenceState("yourtexthere")
  • SetPresenceDetails("yourtexthere")
  • SetPresenceLargeImage("yourimagenamehere", isLink) - Text has to be the same name as the asset, the false or true determines if the image is a link or not.
  • SetPresenceLargeText("yourtexthere")
  • SetPresenceSmallImage("yourimagenamehere", isLink) - Text has to be the same name as the asset, the false or true determines if the image is a link or not.
  • SetPresenceSmallText("yourtexthere")
  • UpdatePresence() - Sends over the updates to Discord.
  • ClearPresence() - Clears everything from your current activity.
  • ClearPresenceType() - Clears a specific type of activity.
• Video Player has been ported over from CD, allowing any video to be played. (Videos must be in .ogv, and placed in "Data/Videos")
• Compatibility with mods / projects that run on the older syntax.
• Many original limitations have been hugely buffed (e.g. more chunks, tiles, and objects can be in a stage, music file size can be larger, etc)
• Objects that use animation files (e.g. players) now support ink effects.
• New username feature, if you have Steam enabled it'll automatically use your Steam username on first launch. Otherwise, it can be set from the settings.ini.
• New functions:
  • PauseSfx(SfxName) - Pauses the defined SFX.
  • ResumeSFX(SfxName) - Resumes the defined SFX.
  • SetClassicFade(r, g, b, alpha) - Works exactly like SetScreenFade but the fading itself is more like the Classics.
  • CheckUpdates("GitHubPageLink") - Checks whether your game needs an update.
  • LoadWebsite("WebsiteLink") - Opens up any web link into your browser (please don't abuse this...)
  • VibrateController(controllerID, intensity, timer) - Determines whether or not the controller should vibrate.
  • SetControllerLEDColour(controllerID, r, g, b) - (PLAYSTATION CONTROLLERS ONLY) Changes the colour of the LED on a controller.
  • CheckAnyButtonPressed() - Stores any button you've just pressed, whether on keyboard or controller (recorded in SDL2 keycodes.)
  • CheckControllerConnect() - Checks whether a controller has been connected.
  • CheckControllerDisconnect() - Checks whether a controller has been disconnected.
  • CheckMouseMoved() - Checks whether the cursor has been moved anytime.
  • CheckMouseLeftPress() - Checks whether the left mouse button has been pressed.
  • CheckMouseRightPress() - Checks whether the right mouse button has been pressed.
  • GetPlaytimeHours() - Gets the playtime in hours.
  • GetPlaytimeMinutes() - Gets the playtime in minutes.
  • GetPlaytimeSeconds() - Gets the playtime in seconds.
  • GetUsername(textMenu) - Grabs the username from the settings.ini.
  • SetUsername("NewName") - Sets the username and saves it into the settings.ini.
• New variables:
  • "engine.platformID" - Restored back into v4 and stores the platform you're currently playing on.
  • "temp8"
  • "temp9"
  • "temp10"
  • "menu3.selection"
  • "menu4.selection"
  • "key.pressed[SDL_SCANCODE]" - Checks if a certain key is pressed, refer to here to check the value of a specific scancode.
  • "key.down[SDL_SCANCODE]" - Same as above, but this time it's held down.
  • "controller.pressed[BUTTON_ID]" - Checks if a certain controller button is pressed, refer to here to check the value of a specific button.
  • "controller.down[BUTTON_ID]" - Same as above, but this time it's held down.
  • "game.checkForUpdates" - Links with CheckUpdates in the settings.ini, and allows for update checking.
  • "game.networkPing" - Returns the amount of time it takes to update when using network features.
  • "controller.device" - Returns the current controller type, refer to Script.cpp for what each value means.
  • "controller.wired" - Returns whether your controller is being used through a wire or not.
  • "controller.vibrationEnabled" - Links with ControllerVibration in the settings.ini, and allows a controller to vibrate.
  • "tempStr0/1/2/3/4/5/6/7/8/9/10" - Temporary values that hold text.
  • "system.timeYear" - Grabs the year value from your system clock.
  • "system.timeMonth" - Grabs the month value from your system clock.
  • "system.timeDay" - Grabs the day value from your system clock.
  • "system.timeHour" - Grabs the hour value from your system clock.
  • "system.timeMinute" - Grabs the minute value from your system clock.
  • "system.timeSecond" - Grabs the seconds value from your system clock.
  • "discord.enableRPC" - (DISCORD SDK MUST BE INSTALLED AND TURNED ON) Enables or disables the use of Discord RPC in the settings.ini.
  • "gamepad.batteryLevel" - The status of your gamepad battery level.
  • "engine.windowFocused" - Checks whether the window is focussed or not.
  • "engine.usernameLength" - Grabs the value of the length of the username you set in settings.ini.
• New aliases:
  • "FX_HSCALE" - Horizontal scaling of a sprite.
  • "FX_VSCALE" - Vertical scaling of a sprite.
  • "FX_ALL" - New FX command for DrawSpriteFX, and allows for every effect to be used at once.
  • "MENU_3"
  • "MENU_4"
  • "RETRO_WIN" - Used for engine.platformID
  • "RETRO_OSX" - Used for engine.platformID
  • "RETRO_XBOX_360" - Used for engine.platformID
  • "RETRO_PS3" - Used for engine.platformID
  • "RETRO_iOS" - Used for engine.platformID
  • "RETRO_ANDROID" - Used for engine.platformID
  • "RETRO_WP7" - Used for engine.platformID
  • "RETRO_UWP" - Used for engine.platformID
  • "RETRO_LINUX" - Used for engine.platformID
  • "RETRO_SWITCH" - Used for engine.platformID
• New native functions (used via "CallNativeFunction"/"2"/"4" - be sure to add these as values in GameConfig.bin/Game.xml!)
  • GetModID("ModName") - Gets the ID of any mod in in the mod list via name and stores it in the checkResult (this could be used for checking if another mod is enabled, allowing for improved compatibility.)
  • GetModAuthorURL() - Gets the the AuthorURL from a certain mod and stores it in a text menu.
• ModAPI Adjustments
  • "AuthorURL" - Add a URL to one of your social media pages, whatever it could be. Can pair well with LoadWebsite to open from in the engine.
• PLEASE MESSAGE ME ON DISCORD IF YOU ARE HAVING ANY TROUBLE WITH GETTING THESE FUNCTIONS WORKING - MY USERNAME IS prodnw.

Fork Credits

• ProdNW - Code porting, new functions, other fixes
• Jd - Video Player, SteamAPI, Discord RPC
• Elspeth - Graphical FX additions, script parsing additions, other fixes
• LittlePlanetCD - Code optimizations
• EggBanana - New functions, other fixes
• SDG - Controller Vibration
• Geared - Other misc. stuff
• Skyward - Other misc. stuff
• AlyStyle - v4+ Icon

To-Dos:

• Improve online by a LOT, this would mean lobbies for competition, lobbies for co-op, better servers, etc.
• Port plenty of features from previous RSDK versions that aren't in v4.
• Backport a huge variety of features from v5/v5u (e.g. DrawLine, PNG Images, and more.)
• Continue adding plenty of QoL features along with fixing any normal v4 bugs.

ModAPI To-Dos:

• Add mod icons, would be useful to show if there is a big list of mods.
• Add a feature for mod dependencies which checks if you have a certain mod installed for another to work properly.

SUPPORT THE OFFICIAL RELEASE OF SONIC 1 & 2

• Without assets from the official releases, this decompilation will not run.

• You can get official releases of Sonic 1 & Sonic 2 from:

  • Windows
    • Via Steam, from Sonic Origins
    • Via the Epic Games Store, from Sonic Origins
  • iOS
    • Sonic 1, Via the App Store
    • Sonic 2, Via the App Store
    • A tutorial for finding the game assets from the iOS versions can be found here.
  • Android
    • Sonic 1, Via Google Play
    • Sonic 2, Via Google Play
    • Sonic 1, Via Amazon
    • Sonic 2, Via Amazon
    • A tutorial for finding the game assets from the Android versions can be found here.

Even if your platform isn't supported by the official releases, you must buy or officially download it for the assets (you don't need to run the official release, you just need the game assets).

If you want to transfer your save(s) from the official mobile version(s), the Android pre-forever file path is Android/data/com.sega.sonic1 or 2/SGame.bin (other versions may have different file paths). Copy that file into the decompilation's folder with the name SData.bin.

Additional Tweaks

• Added the built in script compiler from RSDKv5U.
• Added a built in mod loader and API, allowing to easily create and play mods with features such as save file redirection, custom achievements and XML GameConfig data.
• Custom menu and networking system for Sonic 2 multiplayer, allowing anyone to host and join servers and play 2P VS.
  • Servers may be unreliable; this feature is more or less a proof of concept.
• Egg Gauntlet Zone is playable in the Time Attack menu in Sonic 2, if you're using a version of the game that includes it.
• There is now a settings.ini file that the game uses to load all settings, similar to Sonic Mania.
• The dev menu can now be accessed from anywhere by pressing the ESC key if enabled in the config.
• The F12 pause, F11 step over & fast forward debug features from Sonic Mania have all been ported and are enabled if devMenu is enabled in the config.
• A number of additional dev menu debug features have been added:
  • F1 will load the first scene in the Presentation stage list (usually the title screen).
  • F2 and F3 will load the previous and next scene in the current stage list.
  • F5 will reload the current scene, as well as all assets and scripts.
  • F8 and F9 will visualize touch screen and object hitboxes.
  • F10 will activate a palette overlay that shows the game's 8 internal palettes in real time.
• Added the idle screen dimming feature from Sonic Mania Plus, as well as allowing the user to disable it or set how long it takes for the screen to dim.

How to Build

This project uses CMake, a versatile building system that supports many different compilers and platforms. You can download CMake here. (Make sure to enable the feature to add CMake to the system PATH during the installation!)

Get the source code

DO NOT download the source code ZIP archive from GitHub, as they do not include the submodules required to build the decompilation.

Instead, you will need to clone the repository using Git, which you can get here.

Clone the repo recursively, using: git clone --recursive https://github.com/prodnw/rsdkv4-plus.git

If you've already cloned the repo, run this command inside of the repository: git submodule update --init --recursive

Getting dependencies

Windows

To handle dependencies, you'll need to install Visual Studio Community (make sure to install the Desktop development with C++ package during the installation) and vcpkg (You only need to follow 1 - Set up vcpkg).

After installing those, run the following in Command Prompt (make sure to replace [vcpkg root] with the path to the vcpkg installation!):

• [vcpkg root]\vcpkg.exe install glew sdl2 libogg libtheora libvorbis --triplet=x64-windows-static (If you're compiling a 32-bit build, replace x64-windows-static with x86-windows-static.) Add curl before --triplet= to use cURL/the update checker.

Finally, follow the compilation steps below using -DCMAKE_TOOLCHAIN_FILE=[vcpkg root]/scripts/buildsystems/vcpkg.cmake -DVCPKG_TARGET_TRIPLET=x64-windows-static -DCMAKE_PREFIX_PATH=[vcpkg root]/installed/x64-windows-static/ as arguments for cmake -B build.

• Make sure to replace each instance of [vcpkg root] with the path to the vcpkg installation!
• If you're compiling a 32-bit build, replace each instance of x64-windows-static with x86-windows-static.

Linux

Install the following dependencies: then follow the compilation steps below:

• pacman (Arch): sudo pacman -S base-devel cmake glew sdl2 libogg libtheora libvorbis
• apt (Debian/Ubuntu): sudo apt install build-essential cmake libglew-dev libglfw3-dev libsdl2-dev libogg-dev libtheora-dev libvorbis-dev
• rpm (Fedora): sudo dnf install make gcc cmake glew-devel glfw-devel SDL2-devel libogg-devel libtheora-devel libvorbis-devel zlib-devel
• apk (Alpine/PostmarketOS) sudo apk add build-base cmake glew-dev glfw-dev sdl2-dev libogg-dev libtheora-dev libvorbis-dev
• Your favorite package manager here, make a pull request
• To use cURL/the update checker, you may have to run one of the following commands depending on your system;
  • pacman (Arch): sudo pacman -S curl
  • apt (Debian/Ubuntu): sudo apt install libcurl4-openssl-dev
  • rpm (Fedora): sudo dnf install libcurl-devel

TODO - apk

• apk (Alpine/PostmarketOS) sudo apk add

Android

Follow the android build instructions here.

Compiling

Compiling is as simple as typing the following in the root repository directory:

cmake -B build
cmake --build build --config release

The resulting build will be located somewhere in build/ depending on your system.

The following cmake arguments are available when compiling:

• Use these by adding -D[flag-name]=[value] to the end of the cmake -B build command. For example, to build with RETRO_DISABLE_PLUS set to on, add -DRETRO_DISABLE_PLUS=on to the command.

RSDKv4 flags

• RETRO_REVISION: What revision to compile for. Takes an integer, defaults to 3 (Origins).
• RETRO_DISABLE_PLUS: Whether or not to disable the Plus DLC. Takes a boolean (on/off): build with on when compiling for distribution. Defaults to off.
• RETRO_FORCE_CASE_INSENSITIVE: Forces case insensivity when loading files. Takes a boolean, defaults to off.
• RETRO_MOD_LOADER: Enables or disables the mod loader. Takes a boolean, defaults to on.
• RETRO_NETWORKING: Enables or disables networking features used for Sonic 2's 2P VS mode. Takes a boolean, defaults to on.
• RETRO_USE_HW_RENDER: Enables the Hardware Renderer used by the main menu and touch controls UI. Takes a boolean, defaults to on.
• RETRO_ORIGINAL_CODE: Removes any custom code. A playable game will not be built with this enabled. Takes a boolean, defaults to off.
• RETRO_SDL_VERSION: Only change this if you know what you're doing. Switches between using SDL1 or SDL2. Takes an integer of either 1 or 2, defaults to 2.
• RETRO_USE_STEAM: Enables the use of the SteamAPI, which can detects if you own Sonic Origins and enable features specific to Origins. It also detects if you own Sonic Origins Plus and enables those features as well, defaults to off, requires the Steamworks SDK extracted to ./dependencies/all/steamworks_sdk.
• RETRO_USE_DISCORD: Toggles whether or not Discord RPC is enabled, defaults to on if not on Android, requires the Discord SDK sdk folder extracted to ./dependencies/all/discord_game_sdk.
  • Unfortunatly, on Linux, you must rename ./dependencies/all/discord_game_sdk/lib/x86_64/discord_game_sdk.so from discord_game_sdk.so to libdiscord_game_sdk.so.
• RETRO_USE_CURL: Adds support for cURL, which is used for loading websites, defaults to off.
• RETRO_UPDATE_CHECKER: Adds support for the update checker, which is used for checking updates, defaults to on if not on Android, forces RETRO_USE_CURL to be set to on.
• RETRO_ACCEPT_OLD_SYNTAX: Adds back aliases that were previously defined within the engine and not the script, allowing compatibility for mods that were made with the old syntax, defaults to off.
• RETRO_ICON_NAME: Sets the icon for the built executable to use, defaults to RSDKv4 Decomp Icon.ico.
• RETRO_VANILLA_LIKE: Brings back the original limitations of RSDKv4, while keeping new the features, defaults to off.

Unofficial Branches

Follow the installation instructions in the readme of each branch.

• For the PlayStation Vita, go to Xeeynamo's fork.
• For the Nintendo Switch, go to heyjoeway's fork.
• For the Nintendo 3DS, go to JeffRuLz's fork.
  • A New Nintendo 3DS is required for the games to run smoothly.
• To play it on the web using Wasm, go to mattConn's fork.

Because these branches are unofficial, we can't provide support for them and they may not be up-to-date.

Other Platforms

Currently the only supported platforms are the ones listed above, however the backend uses libogg, libvorbis & SDL2 to power it (as well as tinyxml2 for the mod API and asio for networking), so the codebase is very multiplatform. If you're able to, you can clone this repo and port it to a platform not on the list.

Server

The multiplayer server requires Python 3.8 or later. You can download Python here. To use the server, open Command Prompt in the folder Server.py is located in, then run the command py -3 Server.py [local IPv4 address] [port] debug. You can find your local IPv4 address using the command ipconfig. Note that the C++ server found in the Server folder has been deprecated and no longer works. It has been kept in the repo for reference purposes.

FAQ

You can find the FAQ here.

Special Thanks

• st×tic for helping me fix bugs, tweaking up my sometimes sloppy code and generally being really helpful and fun to work with on this project.
• biscuitball425: for creating the header logo along with similar assets.
• Everyone in the Retro Engine Modding Server for being supportive of me and for giving me a place to show off these things that I've found.

Contact:

Join the Retro Engine Modding Discord Server for any extra questions you may need to know about the decompilation or modding it.