A sandbox framework to fast-prototype tile-based games

Pixelbox takes inspiration from fantasy consoles like PICO8 and game creation frameworks like Unity3D.

Install

From version 2, the Pixelbox package no longer includes the editor. Instead, the editor is now a standalone application that can be downloaded on Itch.io.

Use

A Pixelbox project has the following structure:

assets/
 ├── tilesheet.png
 ├── palette.png
 └── maps.json
audio/
build/
src/
 └── main.js
tools/
node_modules/
project.pixelbox
package.json
index.html

• assets/ is where game assets go (images, text files, JSON)
• audio/ is where sounds and music go
• src/ is the source code folder, and main.js is the entry file of the game

Programming with pixelbox

Program structure

The game entry point is the src/main.js file. If you provide an exports.update function, Pixelbox will call it every frame.

Building is done using browserify which gives you access to require (or import) and exports to easily modularize your project.

Assets

Pixelbox automatically loads all assets at startup, before executing the game code. All supported files added inside the assets/ directory will be available in the assets global object. The structure follows the structure of the directory. For instance, the file located in assets/sprites/player.png will be accessible with assets.sprites.player.

Supported files include:

• images (.png, .jpg)
• JSON formatted data (.json)
• plain text files (.txt, .css, .vert, .frag)

You have direct access to the content of JSON files.

Because files are loaded inside the assets object and refered wthout their extension, you cannot have a file and a directory with the same name inside the same directory.

Pixelbox API

Pixelbox exposes the following methods directly on the global scope:

Drawing graphics

• cls() clear screen with paper color
• sprite(n, x, y [,flipH [,flipV [, flipR]]]) draw sprite number n on screen at pixel position (x, y) flipH and flipV can be used to flip sprites horizontally or vertically, flipR adds a 90 degree clockwise rotation
• draw(image, x, y [,flipH [,flipV [, flipR]]]) draw an Image, Texture or TileMap on screen at pixel position (x, y)
• tilesheet(image) change image used as default tilesheet
• rect(x, y, w, h) stroke a rectangle with pen color
• rectf(x, y, w, h) fill a rectangle with paper color
• camera(x, y) scroll add further drawing by provided position

Printing text

Pixelbox has a predefined "minitext" bitmap font that you can use to print text on screen or in textures. Minitext is available by default, but can be disabled in the project settings.

• print(text, [x, y]) if x, y is provided, print text at pixel position (x, y); else print text at cursor current position
• println(text) print text and feed new line; when the cursor reaches the bottom of the screen, vertical scroll is applied (just like it would happen in a terminal)
• locate(i, j) set cursor position at column i line j
• pen(colorId) set text color to colorId in color palette
• paper(colorId) set paper color to colorId in color palette

User controls

• btn state of the buttons — by default, available buttons are: up, down, left, right, A, B (buttons names and binding can be configured in the project settings)
• btnp whether button has been pressed during current frame
• btnr whether button has been released during current frame

Playing sound

• sfx('sound'); play the sound.mp3 file in audio/ folder
• music('bgm'); play the bgm.mp3 file in loop; if another music is already playing, it will cross fade to the new music; if no soundId is provided, music stops

AudioManager is the module that handles audio loading and playback. You have access to its instance on audioManager.

Other utility functions

• clamp(value, min, max) clip a value between min and max
• chr$(n) return a character from code n
• random(n) return a random integer between 0 and n
• inherits(Child, Parent) make class Child inherit from class Parent

Pixelbox components

Texture

Texture is a canvas that can be drawn, and inside which things can be drawn. In Canvas2D mode, it is implemented with a HTML canvas. In WebGL mode, it is implemented with a GLTexture2D.

The main screen (accessible by the global variable $screen) is an instance of Texture and most of its methods are accessible from the global scope.

To create new texture, you need to require the Texture module:

var Texture = require('pixelbox/Texture');
var texture = new Texture(128, 128); // create a new texture of 128 by 128 pixels

Texture settings

texture.resize(width, height);
texture.setPalette(palette);
texture.pen(colorIndex); // set PEN color index from palette (pen is used for text and stroke)
texture.paper(colorIndex); // set PAPER color index from palette (paper is used for fill)
texture.setTilesheet(tilesheet); // set tilesheet used for this texture

A tilesheet is an Image containing 256 sprites organized in a 16 x 16 grid (the size of the tilesheet depend of the sprite size you set for your game).

Rendering

texture.clear(); // clear texture (it becomes transparent)
texture.cls(); // clear screen (the whole texture is filled with the PAPER color)
texture.sprite(sprite, x, y, flipH, flipV, flipR); // draw a sprite from current tilesheet in the texture
texture.draw((img, x, y, flipH, flipV, flipR); // draw an image (or Texture or Map) in the texture
texture.rect(x, y, width, height); // stroke a rectangle
texture.rectf(x, y, width, height); // fill a rectangle

Printing text

texture.locate(i, j); // set text cursor to specified location
texture.print(text, x, y); // print some text
texture.println(text); // print some text and feed a new line

Tile Maps

Pixelbox has a built-in TileMap component. A TileMap consist of:

• A name
• A tilesheet — when the tilesheet is changed, the whole map will be redrawn with the new tilesheet
• A grid of sprites from the tilesheet plus few flags to flip or rotate sprites

Once created, a tile map is rendered in one draw call only.

TileMap can be used to render a level made of sprites, or just to store game data.

You can create tile maps from your game code; But usually, you will be using Pixelbox's tools (see the Tools section below) to create and manage your maps as game assets. A map can then be retrieved by its name with Pixelbox's getMap function. The tile map can then be drawn on screen (or in another Texture), modified, copied, pasted, resized, etc.

When stored in assets, the map is compressed to Pixelbox format to reduce file size.

Get tile map

var map = getMap('mapName'); // get a tile map by its name

To create new maps, you need to require the Map module:

var TileMap = require('pixelbox/TileMap');
var map = new TileMap(16, 16); // create a new tile map of 16 by 16 tiles

Draw map

map.draw(x, y);  // draw map on screen at [x, y] position
draw(map, x, y); // idem, using the global draw function
texture.draw(map, x, y); // draw a map in another texture
map.setTilesheet(tilesheet); // set tilesheet to use for this map
                             // The whole map is redrawn when calling this function

Access map content

map.get(x, y); // returns the Tile at position [x, y]. null if empty
map.set(x, y, tile, flipH, flipV, flipR, flagA, flagB); // add a tile
map.remove(x, y); // remove tile at position [x, y]. (set it to null)
map.find(tile, flagA, flagB); // find all tiles with specified properties

Modifying maps programatically

map.resize(width, height); // resize the map (size unit is tiles)
map.clear(); // Reset the whole map content by setting all its tiles to null
var mapCopy = map.copy(x, y, width, height); // copy this map to a new one
               // x, y, width, height can be specified to copy only a rectangular part of the map
map.paste(mapCopy, x, y, merge); // paste map data in the map at position offset [x, y]
               // if 'merge' flag is set, then null tiles will not overwrite current map tile

Gamepad

The gamepad module allows for easy access to gamepads if the browser supports it. When the gamepad feature is enabled in the project settings, you get access to these objects on the global scope:

gamepads[id]; // get gamepad state. id is a number in the range [0..4] (4 is computer keyboard)
gamepad; // Merge states of all gamepads and return a global gamepad state.

Gamepad state works like keyboard controls: You get the state of each button, button presses and button releases, plus the values of analog controls.

var state = gamepads[0]; // get state of gamepad id 0

// buttons:
state.btn.A; // state of A button
state.btn.B; // state of B button
state.btn.X; // state of X button
state.btn.Y; // state of Y button
state.btn.start; // state of 'start' button
state.btn.back;  // state of 'back' button
state.btn.up;    // directionnal pad's up button
state.btn.down;  // directionnal pad's down button
state.btn.left;  // directionnal pad's left button
state.btn.right; // directionnal pad's right button
state.btn.lb; // left bumper button
state.btn.rb; // right bumper button
state.btn.lt; // left trigger button
state.btn.rt; // right trigger button

// button press and release.
// the structure is the same as state.btn but the values are true only
// on button press or release.
state.btnp; // button press
state.btnr; // button release

// analog values
state.x  // x axe value (first stick horizontal)
state.y  // y axe value (first stick vertical)
state.z  // z axe value (second stick horizontal)
state.w  // w axe value (second stick vertical)
state.lt // left trigger analog value
state.rt // right trigger analog value

PataTracker

Pixelbox editor is bundled with a music tracker called PataTracker. The tracker player must be enabled in the project settings. Player allows to directly plays the songs in the json formatted tracker files.

PataTracker player is exposed as a patatracker global variable.

patatracker.playSong(songNumber);
patatracker.stop();

PataTracker automatically loads the project's album data (assets/patatracker.json). If you need to load a different album, you can do it with the following API:

patatracker.loadData(data);

Bleeper

Bleeper is the sound effect editor of Pixelbox. Like for PataTracker, it must be enabled in the project settings. Note that Bleeper depends on the AudioManager component.

There are several ways to play Bleeper sounds:

Named sounds

If the sound is named, it is accessible on the assets global, and automatically added to AudioManager.

// from assets global
assets.bleeper.mySound.play(volume, panoramic, pitch); // all parameters optional

// using audioManager
sfx('mySound', volume, panoramic, pitch); // using default channel
audioManager.playSound('sfx', 'mySound', volume, panoramic, pitch);

Using bleeper module

The Bleeper module exposes an array of all sounds defined in the program.

var bleeper = require('pixelbox/bleeper');
bleeper.sounds[3].play(volume, panoramic, pitch);