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A retro game engine for Python
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README.md

[ English | 日本語 | Other Languages ]

Pyxel is a retro game engine for Python.

Thanks to its simple specifications inspired by retro gaming consoles, such as only 16 colors can be displayed and only 4 sounds can be played back at the same time, you can feel free to enjoy making pixel art style games.

The specifications of the gaming console, APIs, and palettes of Pyxel are referring to awesome PICO-8 and TIC-80.

Pyxel is open source and free to use. Let's start making a retro game with Pyxel!

Specifications

  • Run on Windows, Mac, and Linux
  • Code writing with Python3
  • Fixed 16 color palette
  • 256x256 sized 3 image banks
  • 256x256 sized 8 tilemaps
  • 4 channels with 64 definable sounds
  • 8 musics which can combine arbitrary sounds
  • Keyboard, mouse, and gamepad inputs
  • Image and sound editor

Color Palette

How to Install

Windows

After installing Python3, the following pip command installs Pyxel:

pip install pyxel

Mac

After installing Python3 and glfw (version 3.2.1 or higher), install Pyxel with pip command.

If Homebrew package manager is ready, the following command installs all the necessary packages:

brew install python3 glfw
pip3 install pyxel

Linux

Install the required packages in a way appropriate for each distribution. glfw must be version 3.2.1 or higher.

Ubuntu / Debian:

sudo apt install python3 python3-pip libglfw3 libportaudio2
sudo pip3 install pyxel

Fedora:

sudo dnf install glfw portaudio
sudo pip3 install pyxel

When installation fails

There seems to be a case where Pyxel installation fails due to the influence of pip's previous cache. In that case, try running the pip command with the following option.

Windows:

pip install --no-cache-dir --ignore-installed pyxel

Mac:

pip3 install --no-cache-dir --ignore-installed pyxel

Linux:

sudo pip3 install --no-cache-dir --ignore-installed pyxel

Install examples

After installing Pyxel, the examples of Pyxel will be copied to the current directory with the following command:

install_pyxel_examples

The examples can be executed like normal Python code:

Windows:

cd pyxel_examples
python 01_hello_pyxel.py

Mac / Linux:

cd pyxel_examples
python3 01_hello_pyxel.py

How to Use

Create a Pyxel Application

After importing the Pyxel module in your python code, specify the window size with init function first, then starts the Pyxel application with run function.

import pyxel

pyxel.init(160, 120)

def update():
    if pyxel.btnp(pyxel.KEY_Q):
        pyxel.quit()

def draw():
    pyxel.cls(0)
    pyxel.rect(10, 10, 20, 20, 11)

pyxel.run(update, draw)

The arguments of run function are update function to update each frame and draw function to draw screen when necessary.

In an actual application, it is recommended to wrap pyxel code in a class as below:

import pyxel

class App:
    def __init__(self):
        pyxel.init(160, 120)
        self.x = 0
        pyxel.run(self.update, self.draw)

    def update(self):
        self.x = (self.x + 1) % pyxel.width

    def draw(self):
        pyxel.cls(0)
        pyxel.rect(self.x, 0, self.x + 7, 7, 9)

App()

Special Controls

The following special controls can be performed while a Pyxel application is running:

  • Alt(Option)+1
    Save the screenshot to the desktop
  • Alt(Option)+2
    Reset the recording start time of the screen capture video
  • Alt(Option)+3
    Save the screen capture video (gif) to the desktop (up to 30 seconds)
  • Alt(Option)+0
    Toggle the performance monitor (fps, update time, and draw time)
  • Alt(Option)+Enter
    Toggle full screen

Pyxel Editor

The attached Pyxel Editor can create images and sounds used in a Pyxel application.

Pyxel Editor starts with the following command:

pyxeleditor [pyxel_resource_file]

If the specified Pyxel resource file (.pyxel) exists, the file is loaded, and if it does not exist, a new file is created with the specified name. If the resource file is omitted, the name is my_resource.pyxel.

After starting Pyxel Editor, the file can be switched by dragging and dropping another resource file.

The created resource file can be loaded with the load function.

Pyxel Editor has the following edit modes.

Image Editor:

The mode to edit the image banks.

By dragging and dropping a png file onto the Image Editor screen, the image can be loaded into the currently selected image bank.

Tilemap Editor:

The mode to edit tilemaps in which images of the image banks are arranged in a tile pattern.

Sound Editor:

The mode to edit sounds.

Music Editor:

The mode to edit musics in which the sounds are arranged in order of playback.

Other resource creation methods

Pyxel images and tilemaps can also be created in the following way:

  • Create an image from a list of strings with Image.set or Tilemap.set function
  • Load a png file in Pyxel palette with Image.load function

Because Pyxel uses the same palette as PICO-8, when creating png images for Pyxel, it is recommended to use Aseprite in PICO-8 palette mode.

Pyxel sounds can also be created in the following way:

  • Create a sound from strings with Sound.set or Music.set function

Please refer to the API reference for usage of these functions.

API Reference

System

  • width, height
    The width and height of the screen

  • frame_count
    The number of the elapsed frames

  • init(width, height, [caption], [scale], [palette], [fps], [border_width], [border_color])
    Initialize the Pyxel application with screen size (width, height). The maximum width and height of the screen is 255
    It is also possible to specify the window title with caption, the display magnification with scale, the palette color with palette, the frame rate with fps, and the margin width and color outside the screen with border_width and border_color. palette is specified as a list of 16 elements of 24 bit color, border_color as 24 bit color

  • run(update, draw)
    Start the Pyxel application and call update function for frame update and draw function for drawing

  • run_with_profiler(update, draw)
    Start the Pyxel application with profiler and call update function for frame update and draw function for drawing. Then output processing time of each function when the application is finished

  • quit()
    Quit the Pyxel application at the end of the current frame

Resource

  • save(filename)
    Save the resource file (.pyxel) to the directory of the execution script

  • load(filename)
    Read the resource file (.pyxel) from the directory of the execution script

Input

  • mouse_x, mouse_y
    The current position of the mouse cursor

  • btn(key)
    Return True if key is pressed, otherwise return False (key definition list)

  • btnp(key, [hold], [period])
    Return True if key is pressed at that frame, otherwise return False. When hold and period are specified, True will be returned at the period frame interval when the key is held down for more than hold frames

  • btnr(key)
    Return True if key is released at that frame, otherwise return False

  • mouse(visible)
    If visible is True, show the mouse cursor. If False, hide it. Even if the mouse cursor is not displayed, its position is updated.

Graphics

  • image(img, [system])
    Operate the image bank img(0-2) (see the Image class). If system is True, the image bank 3 for system can be accessed
    e.g. pyxel.image(0).load(0, 0, 'title.png')

  • tilemap(tm)
    Operate the tilemap tm(0-7) (see the Tilemap class)

  • clip(x1, y1, x2, y2)
    Set the drawing area of the screen to (x1, y1)-(x2, y2). Reset the drawing area with clip()

  • pal(col1, col2)
    Replace color col1 with col2 at drawing. pal() to reset to the initial palette

  • cls(col)
    Clear screen with color col

  • pix(x, y, col)
    Draw a pixel of color col at (x, y)

  • line(x1, y1, x2, y2, col)
    Draw a line of color col from (x1, y1) to (x2, y2)

  • rect(x1, y1, x2, y2, col)
    Draw a rectangle of color col from (x1, y1) to (x2, y2)

  • rectb(x1, y1, x2, y2, col)
    Draw the outline of a rectangle of color col from (x1, y1) to (x2, y2)

  • circ(x, y, r, col)
    Draw a circle of radius r and color col at (x, y)

  • circb(x, y, r, col)
    Draw the outline of a circle of radius r and color col at (x, y)

  • blt(x, y, img, u, v, w, h, [colkey])
    Copy the region of size (w, h) from (u, v) of the image bank img(0-2) to (x, y). If negative value is set for w and/or h, it will reverse horizontally and/or vertically. If colkey is specified, treated as transparent color

  • bltm(x, y, tm, u, v, w, h, [colkey])
    Draw the tilemap tm(0-7) to (x, y) according to the tile information of size (w, h) from (u, v). If colkey is specified, treated as transparent color. A tile of the tilemap is drawn with a size of 8x8, and if the tile number is 0, indicates the region (0, 0)-(7, 7) of the image bank, if 1, indicates (8, 0)-(15, 0)

  • text(x, y, s, col)
    Draw a string s of color col at (x, y)

Audio

  • sound(snd, [system])
    Operate the sound snd(0-63) (see the Sound class). If system is True, the sound 64 for system can be accessed
    e.g. pyxel.sound(0).speed = 60

  • music(msc)
    Operate the music msc(0-7) (see the Music class)

  • play(ch, snd, loop=False)
    Play the sound snd(0-63) on channel ch(0-3). Play in order when snd is a list

  • playm(msc, loop=False)
    Play the music msc(0-7)

  • stop([ch])
    Stop playback of all channels. If ch(0-3) is specified, stop the corresponding channel only

Image Class

  • width, height
    The width and height of the image

  • data
    The data of the image (NumPy array)

  • get(x, y)
    Retrieve the data of the image at (x, y)

  • set(x, y, data)
    Set the data of the image at (x, y) by a value or a list of strings
    e.g. pyxel.image(0).set(10, 10, ['1234', '5678', '9abc', 'defg'])

  • load(x, y, filename)
    Read the png image from the directory of the execution script at (x, y)

  • copy(x, y, img, u, v, w, h)
    Copy the region of size (w, h) from (u, v) of the image bank img(0-2) to (x, y)

Tilemap Class

  • width, height
    The width and height of the tilemap

  • data
    The data of the tilemap (NumPy array)

  • refimg
    The image bank referenced by the tilemap

  • get(x, y)
    Retrieve the data of the tilemap at (x, y)

  • set(x, y, data, [refimg])
    Set the data of the tilemap at (x, y) by a value or a list of strings. If refimg is specified, the image bank referenced by the tilemap is also set
    e.g. pyxel.tilemap(0).set(0, 0, ['000102', '202122', 'a0a1a2', 'b0b1b2'], 1)

  • copy(x, y, tm, u, v, w, h)
    Copy the region of size (w, h) from (u, v) of the tilemap tm(0-7) to (x, y)

Sound Class

  • note
    List of note(0-127) (33 = 'A2' = 440Hz)

  • tone
    List of tone(0:Triangle / 1:Square / 2:Pulse / 3:Noise)

  • volume
    List of volume(0-7)

  • effect
    List of effects(0:None / 1:Slide / 2:Vibrato / 3:FadeOut)

  • speed
    The length of one note(120 = 1 second per tone)

  • set(note, tone, volume, effect, speed)
    Set a note, tone, volume, and effect with a string. If the tone, volume, and effect length are shorter than the note, it is repeated from the beginning

  • set_note(note)
    Set the note with a string made of 'CDEFGAB'+'#-'+'0123' or 'R'. Case-insensitive and whitespace is ignored
    e.g. pyxel.sound(0).set_note('G2B-2D3R RF3F3F3')

  • set_tone(tone)
    Set the tone with a string made of 'TSPN'. Case-insensitive and whitespace is ignored
    e.g. pyxel.sound(0).set_tone('TTSS PPPN')

  • set_volume(volume)
    Set the volume with a string made of '01234567'. Case-insensitive and whitespace is ignored
    e.g. pyxel.sound(0).set_volume('7777 7531')

  • set_effect(effect)
    Set the effect with a string made of 'NSVF'. Case-insensitive and whitespace is ignored
    e.g. pyxel.sound(0).set_effect('NFNF NVVS')

Music Class

  • ch0
    List of sound(0-63) play on channel 0

  • ch1
    List of sound(0-63) play on channel 1

  • ch2
    List of sound(0-63) play on channel 2

  • ch3
    List of sound(0-63) play on channel 3

  • set(ch0, ch1, ch2, ch3)
    Set the list of sound(0-63) of all channels
    e.g. pyxel.music(0).set([0, 1], [2, 3], [4], [])

  • set_ch0(data)
    Set the list of sound(0-63) of channel 0

  • set_ch1(data)
    Set the list of sound(0-63) of channel 1

  • set_ch2(data)
    Set the list of sound(0-63) of channel 2

  • set_ch3(data)
    Set the list of sound(0-63) of channel 3

How to Contribute

Submitting an issue

Use the issue tracker to submit bug reports and feature/enhancement requests. Before submitting a new issue, search the issue tracker to ensure that there is no similar open issue.

When submitting a report, select the appropriate template from this link.

Manual testing

Anyone manually testing the code and reporting bugs or suggestions for enhancements in the issue tracker are very welcome!

Submitting a pull request

Patches/fixes are accepted in form of pull requests (PRs). Make sure the issue the pull request addresses is open in the issue tracker.

Submitted pull request is deemed to have agreed to publish under MIT license.

Other Information

License

Pyxel is under MIT license. It can be reused within proprietary software provided that all copies of the licensed software include a copy of the MIT License terms and the copyright notice.

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