prosperon/doc/prosperon.org

Prosperon Documentation

• Getting Started
  • Installation
    • Linux & MacOS
    • Windows
  • Playing your first game
• Engine Tour
  • QuickJS (Javascript)
  • Script entry points
  • Actors
    • Actor Lifetime
    • Turns
    • Actor files
    • Actor configuration
  • Entities
    • Adding Components
    • Ur system
    • Prototyping Entities
    • Spawning
    • Resources
      • Links
    • Ur auto creation
  • Input
    • Editor input
  • GUI
• Editor Tour
  • Editing entities
  • The REPL¹
  • Playing the game
  • Script Editor
    • Syntax coloring? … nope!
  • Debugging
• Exporting your game
  • Building static content
  • Converting assets
  • Packing into a CDB
• Modding & Patching
  • Shipping

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Getting Started

Press 'i' to see the table of contents. Press '?' for shortcuts on navigating this document!

Installation

Linux & MacOS

Install the most recent binaries into your $PATH.

Windows

Copy the executable into any folder and run it. If no game is deteced, it scaffolds for you.

Playing your first game

Download any of the completed example projects. Run prosperon play in the folder.

Poke around the example projects. You will find it refreshingly straight forward.

Engine Tour

Prosperon is built in a code-first fashion.

QuickJS (Javascript)

The scripting language used in Prosperon is Javascript, with QuickJS. It is ES2023 compliant. It is fast, and has a number of features that make it well suited for a video game engine, like ref counting. Read more about it here.

Javascript is used here mostly to set up objects and tear them down. Although computationally expensive tasks can be done using QuickJS, Prosperon makes it easy to extend with raw C.

Script entry points

The first way you can customize Prosperon is by adding scripts to the folder you're running it from. Any file ending with .js is a script which can be ran by Prosperon.

script	When called
config.js	First script on Prosperon load
game.js	Entry point for running the game
editorconfig.js	Entry point for running the editor
predbg.js	Called before running debug
debug.js	Debug set up
dbgret.js	After stopping debug mode, used for cleanup

Try it out. Add a script called config.js to your folder, with this.

console.log("Hello world!");
Game.quit();

Run prosperon. You will see "Hello world!" in the console, and it shuts down.

Using config.js and game.js, you can write an entire game, without reaching any further. When you want to populate a world with independent actors, entities are what you will reach for.

Actors

The fundamental tool for building in Prosperon is the actor system. Actors run independently from each other. Actors are defined by a combination of code and data. All actors have a master² which controls certain properties of the actor.

The most masterful actor is the Empyrean. The first actor you create will have the Empyrean as its master. Subsequent actors can use any other actor as its master.

Actor Lifetime

When an actor dies, all of the actors that have it as their master³ will die as well.

Turns

Actors get fragments of time called a turn. Actors which belong to different systems can have different lengths of turns.

Actor files

Actor files end with the extension .jso⁴. They list a series of functions to call on a newly formed actor. Actors have a number of useful functions which are called as defined.

function	call time
start	The first function called when the actor is in the world
update	Called once per turn
gui	Called on GUI draw
stop	Called when the actor is killed
gizmo	Called by the editor when the entity is selected

Create a new actor, then kill it.

var act_die_call = function() {
  console.log(`Actor ${this.id} has died.`);
}
var act1 = Empyrean.new();
var act2 = actor1.new();
act1.stop = act_die_call;
act2.stop = act_die_call;
Empyrean.kill(); /* Error: The Empyrean cannot be killed */
act1.kill();
act2.kill(); /* Error: act2 has been killed because act1 was */

Now simplify by putting the code into a file named hello.jso.

this.stop = function() {
  console.log(`Actor ${this.id} has died.`);
}

Now spawn two actors using it.

var act1 = Empyrean.new("hello.jso");
var act2 = act1.new("hello.jso");

Actor configuration

Actors can be created using an optional configuration file. A configuration file is one of any accepted data types. Currently, JSON or Nota. Configuration files are loaded after an actor's script file, overwriting any defined values on it.

Add a name for the actor to take on using a configuration file named hello.json.

{
 "name": "Actor 1"
}

Now create hello.jso to use it.

this.start = function() { console.log(`I, ${this.name}, have been created.`); }

Entities

Game worlds are made of entities. Entities are a type of actor with a number of useful properties. Entities can only be created on the actor named Primum⁵. The Primum is the outermost actor with a physical space. While Actors are more abstract, Entities exist in a definite space, with a position, rotation, and so on. Entities can respond to physics and play sounds. Anything which can be thought of as having a position in space should be an entitiy.

The first and most masterful entity is the Primum. The Primum has no components, and its rotation and position are zero. It defines the center of the game.

Adding Components

Entities can have components. Components are essentially javascript wrappers over C code into the engine. Scripting is done to set the components up on entities, after which most of the work is done by the C plugin.

For example, to render an image, set up a sprite component on an entity and point its path to an image on your harddrive.

var ent = Empyrean.new();
var spr = ent.add_component(component.sprite);
spr.path = "image.png";

Put that into your config file and run prosperon. You should see the contents of "image.png" on the screen.

Try using an animated gif. Prosperon has native support for gif animations!

Components only work in the context of an entity. They have no meaning outside of a physical object in the world. They have no inherent scripting capabilities.

While components can be added via scripting, it is easier to add them via the editor, as we will later see.

Ur system

The ur⁶ system is a prototypical inheritence system used by the actor files. When actor files are loaded, they are stored as an ur. Entities can be created from ur types using the spawn function.

Create an ur from the hello files above, and then spawn it.

ur.create("hello", "hello.jso", "hello.json");
Primum.spawn(ur.hello);

When creating an actor from source files, all of its setup must take place. In this example, the setup happens during ur.create, and spawning is simply a matter of prototyping it.

Each ur type has some useful fields.

field	description
instances	An array of instances of this ur

Prototyping Entities

Ur types are the prototype of created entities. This makes it trivial to change huge swathes of the game, or make tiny adjustments to single objects, in a natural and intuitive way. When a value is changed on an entity, it is private. When a value is changed on an ur, it propogates to all entities. Values cannot be added or removed in subtypes.

Entities all have the following functions to assist with this:

function	use
clone(parent)	Create an entity prototyped from the parent
dup(parent)	Create an exact duplicate of the parent
revert()	Removes all local changes on the entity

Speaking of practical experience, is best for ur prototype chains to be shallow.

Spawning

Actor data and ur types can remember which entities were contained in it when saving. They are stored in the objects field. When an entity with an objects field is spawned, it spawns all of the objects listed in turn.

When an entity is spawned, it is addressable directly through its master entity. Its name is generated from its file or ur type name.

Let's take a simple RPG game.

Primum
 level1
   orc
   goblin
   human
    sword
 ui

The orc, for example, is addressable by Primum.level1.orc. The human has a sword spawned underneath it. When he is killed, his sword also disappears.

Resources

Assets can generally be used simply with their filename. Assets can be modified with a sidecar file named filename.asset, so, a file ball.png can have additional parameters through its ball.png.asset file.

sigil	meaning
/	root of project
@	root of save directory
#	root of link

Resources can be referenced in a relative manner by actor scripts. When it comes to actors using assets, relative filepaths are useful and encouraged.

/
  score.wav
  /bumper
    hit.wav
    bumper.jso
  /ball
    hit.wav
    ball.jso

Path resolution occurs during actor creation. In effect, a reference to hit.wav in bumper.jso will resolve to the absolute path /bumper/hit.wav.

If the asset is not found, it is searched for until the project root is reached. The bumper can reference score.wav and have the path resolution take place. Later, if the it is decided for the bumper to have a unique score sound, a new score.wav can be placed in its folder and it will work without changing any code.

Caution! Because the path is resolved during object load, you will need to fresh the bumper's ur or spawn a new bumper for it to use the newly placed score.wav.

Links

Links can be specified using the "#" sign. These are shortcuts you can specify for large projects. Specify them in the array Resources.links.

An example is of the form trees:/world/assets/nature/trees. Links are called with #, so you can now make a "fern" with Primum.new("#trees/fern.jso").

Ur auto creation

Instead of coding all the ur type creation by hand, Prosperon can automatically search your project's folder and create the ur types for you. Any [name].jso file is converted into an ur with the name. Any [name].json file is then applied over it, should it exist. If there is a .json file without a corresponding .jso, it can still be turned into an ur, if it is a valid ur format.

The folder hierarchy of your file system determines the ur prototype chain. .jso files inside of a folder will be subtyped off the folder ur name.

Only one ur of any name can be created.

@/
  flipper.js
  flipper/
    left.js

@/
  flipper/
    flipper.js
    left/
      left.js

prototypes.generate_ur(path) will generate all ur-types for a given path. You can preload specific levels this way, or the entire game using prototypes.generate_ur('.'). If your game is small enough, this can have a massive runtime improvement.

Input

Input is done in a highly generic and customizable manner. players can take control of any object (actor or otherwise) in Prosperon, after which it is referred to as a pawn of a player. If the object has a defined input object, it is a valid pawn. One player can have many pawns, but each pawn may have only one player.

Pawns are added as a stack, with the newest ones getting priority, and handled first. It is possible for pawns to block input to lower pawns on the stack.

/newest/
car <== When a key is pressed, this is the first pawn to handle input
player
ui <== /block/ is set to true here, so editor recieves no input!
editor
/oldest/

The default player can be obtained with Player.players[0]. Players are all local, and the highest number is determined by platform.

The input object defines a number of keys or actions, with their values being functions.

Editor input

The editor input style defines keystrokes. It is good for custom editors, or any sort of game that requires many hotkeys. Keystrokes are case sensitive and can be augmented with auxiliary keys.

symbol	key
C	ctrl
M	alt
S	super

var orc = Primum.spawn(ur.orc);
orc.inputs = {};
orc.inputs.a = function() { ... };
orc.inputs.A = function() { ... }; /* This is only called with a capital A! */
orc.inputs['C-a'] = function() { ... }; /* Control-a */
Player.players[0].control(orc); /* player 0 is now in control of the orc */

The input object can be modified to customize how it handles input.

property	type	effect
post	function	called after any input is processed
release_post	function	called after any input is released
fallthru	bool	false if input should stop with this
block	bool	true if input should stop with this

The input can be modified by setting properties on the associated function.

property	type	effect
released	function	Called when the input is released
rep	bool	true if holding the input should repeatedly trigger it
down	function	called while the input is down

GUI

Game GUIs are written by registering an entity's gui property to a function.

The GUI system which ships with Prosperon is called MUM. MUM is a declarative, immediate mode interface system. Immediate to eliminate the issue of data synchronization in the game.

All GUI objects derive from MUM. MUM has a list of properties, used for rendering. Mum also has functions which cause drawing to appear on the screen.

Editor Tour

Prosperon's visual editor is an assistant for the creation and editing of your game entities and actors. In the editor, all ur types are loaded, and assets are constantly monitored for changes for hot reloading.

To initiate it, execute prosperon.

Editing entities

The desktop is the topmost entity that exists in the editor. Instead of editing specific files, you simply load them into your desktop, and go from there. This makes it easier to see two different entities simultaneously so you can ensure changes to one are congruous with the vision for the others.

The main editor view is made up of entities. Each entity can have a number of components attached to it. When an entity is selected, its name, position, and list of components are listed.

Basic use of the editor involves spawning new entities, or ones from already made ur types, editing them, and then saving them as new ur types or overwriting the ones they spawned from. Specific tools have been written to make editing components and levels easier than with a text editor, and the editor is easily extendable for your own purposes.

Assign the entity's gizmo property to a function to have that function called each gui rendering frame.

The REPL⁷

The REPL lets you poke around in the game. It makes iteration and experimentation fast, fun, and easy.

The symbol $ references the current REPL entity. If no entity is selected, the REPL entity is the currently edited one. Otherwise, it is the selected entity, or group of entities, as an array.

Easily run commands on multiple entities using Javascript functions like for each.

$.forEach(e => console.log(e.pos));

The REPL is a powerful tool for editing your game. Arbitrary code can be ran in it, meaning any esoteric activity you need done for your game can be done easily. Commonly used functions should be copied into your editorconfig.js to be called and used at will.

Playing the game

Playing the game involves running the game from a special debug.js file, or from the beginning, as if the game were packaged and shipped.

key	action
f5	Play the game, starting with entry point debug.js
f6	Play the game from the beginning

While playing the game, a limited editor is available that allows for simple debugging tasks.

key	action
C-p	Pause
M-p	One time step
C-q	Quit play, return to editor

Script Editor

Prosperon comes with an in-engine script editor. It implements a subset of emacs, and adds a few engine specific features.

Syntax coloring? … nope!

The editor that ships with Prosperon has context coloring, which is a good deal more useful than syntax coloring.

Debugging

Debugging functions are mapped to the F buttons, and are available in any debug build of the game. Pressing the specified key toggles the feature; pressing it with alt shows a legend for that feature.

key	description
F1	Draw physics info
F3	Draw bounding boxes
F12	Draw gui info

Exporting your game

Prosperon is a multiplatform engine. Bundling your game for these platforms essentially involves three steps:

• Baking static content
• Conversion of assets
• Packing into a CDB⁸

To distribute your game for a given platform, run prosperon build {platform}.

platform
Linux
MacOS
Windows

You will find your game ready to go. Rename the executable to the name of your game and run it to play. Congratulations!

Building static content

Static content creation involves any number of optimizations.

• Bitmap font creation
• Texture map creation

Creation of these assets is invisible. Prosperon updates its understanding of how to pull assets based on the existance of these packed ones.

Converting assets

Images, videos, and sounds, are converted to assets most suitable for the target platform. This may be for speed or simple compatability. You do not need to do anything. Use your preferred asset types during production.

Packing into a CDB

A cdb is known as a "constant database". It is a write once type of database, with extremely fast retrieval times. Packing your game into a cdb means to create a database with key:value pairs of the filenames of your game. The Prosperon executable is already packed with a core cdb. Your game assets are packed alongside it as the game cdb.

You can create your game's cdb by running prosperon -b. You will find a game.cdb in the root directory.

Modding & Patching

When an asset is requested in Prosperon, it is searched for in the following manner.

1. The cwd⁹
2. The game cdb (not necessarily present)
3. The core cdb

Game modification is trivial using this described system. By putting an asset in the same path as the asset's location in the game cdb, when that asset is requested it will be pulled from the file system instead of the game cdb.

Given a Prosperon-built game, you can unpack its content into a directory by running prosperon unpack {game}.

Shipping

Once a game's assets are modified, it may be desirable to ship them. Run prosperon patch create {game} to create a patch.cdb filled only with the files that are different compared to those found in the game.cdb in the game.

To update game to use the new patch, run prosperon patch apply {patch}, replacing patch with the name of the cdb file generated above.

Many patches can be bundled by running prosperon patch bundle {list of patches}. This creates a patch that will update the game as if the user had updated each patch in order.

Mods can be distributed with the same idea.

---

¹

Read-eval-print loop

²

I am aware of the ongoing controversy surrounding the use of this term. That is precisely why I have used it: there are a plethora of similar relationships in video games, and by using a term most teams would rather not used, I have saved left the field of avaialable ones wide open

³

What a mouthful!

⁴

"Javascript object".

⁵

See the Primum Mobile

⁶

A German prefix meaning primitive, original, or earliest.

⁷

Read-eval-print loop

⁸

Constant database

⁹

current working directory