Nyan

Nyan - a fork of Python Play - is an open-source code library for the Python programming language that makes it as easy as possible to start making games. Here's the code to make a simple game using Nyan:

import nyan

cat = nyan.new_text('=^.^=', font_size=70)

@nyan.repeat_forever
async def move_cat():
    cat.x = nyan.random_number(-200, 200)
    cat.y = nyan.random_number(-200, 200)
    cat.color = nyan.random_color()

    cat.show()

    await nyan.sleep(seconds=0.4)

    cat.hide()

    await nyan.sleep(seconds=0.4)

@cat.when_clicked
def win_function():
    cat.show()
    cat.text = 'You won!'

nyan.start_program()

The code above makes a game where you have to click the cat to win:

Nyan is an excellent choice for beginner programmers to get started with graphics programming. It was designed to have similar commands and simplicity to MIT's Scratch and is distinguished from such projects as Pygame, Arcade, or Pygame Zero because of its lack of boiler plate code, its easy-to-understand plain-english commands, and intuitive API.

How to install Nyan

Make sure that you have Python 3.7 or greater. Run the following command in your terminal:

pip install nyan

How to use Nyan

All Nyan programs start with import nyan and end with nyan.start_program(), like this:

import nyan # this is the first line in the program

nyan.start_program() # this is the last line in the program

All other commands go between those two commands.

Commands

The rest of this document is divided into the following sections:

• Basic Commands - Getting graphics, shapes, and text on the screen. Also changing the backdrop.
• Animation and Control Commands - Animating and controlling graphics, shapes, and text.
• Sprite Commands - Controlling sprites.
• Mouse Commands - Detecting mouse actions (clicks, movement).
• Keyboard Commands - Detecting keyboard actions.
• Audio Commands - Playing sounds and music.
• Other Useful Commands - General commands.
• Packaging Nyan Programs - Creating an executable that can be shared with other people.

Basic Commands

To get images or text on the screen, use the following commands. (Copy and paste the code below to try it out.)

nyan.new_rect()

box = nyan.new_rect(
        color='black',
        x=0,
        y=0,
        width=100,
        height=200,
        border_color="light blue",
        border_width=10
    )

This will put a tall, black Rectangle in the middle of the screen.

If you want to change where the image is on the screen, try changing x=0 (horizontal position) and y=0 (vertical position). Just like Scratch, the middle of the screen is x=0, y=0. Increasing x moves the image right and decreasing x moves the image left. Likeswise, increasing y moves the image up and decreasing y moves the image down. You can also change the color by changing 'black' to another color name, like 'orange'.

nyan.new_image()

character = nyan.new_image(
        image='character.png', 
        x=0, 
        y=0, 
        size=100
    )

This will place an image in the middle of the screen. Make sure you have a file named character.png in a folder named assets inside your project for the code above to work. You can find images online at sites like OpenGameArt, or you can make your own using an online sprite editor like Piskel.

nyan.new_text()

greeting = nyan.new_text(
        text='hi there', 
        x=0, 
        y=0, 
        font=None, 
        font_size=50, 
        color='black'
    )

This will put some text on the screen.

If you want to change the font, you'll need a font file (usually named something like Arial.ttf) in your assets folder. Then you can change font=None to font='Arial.ttf'. You can find font files at sites like DaFont.

nyan.new_circle()

ball = nyan.new_circle(
        color='black', 
        x=0, 
        y=0, 
        radius=100, 
        border_color="light blue", 
        border_width=10
    )

This will put a black circle in the middle of the screen.

nyan.set_backdrop()

You can change the background color with the nyan.set_backdrop() command:

nyan.set_backdrop('light blue')

There are lots of named colors to choose from. Additionally, if you want to set colors by RGB (Red Green Blue) values, you can do that like this:

# Sets the background to white. Each number can go from 0 to 255
nyan.set_backdrop((255, 255, 255))

Anywhere you can set a color in Nyan, you can do it using a named color like 'red' or an RGB value above like (255, 255, 255) or even an RGBA value like (0, 0, 0, 127) (the fourth number is transparency from 0 to 255).

Animation and Control Commands

@nyan.repeat_forever

To make things move around, you can start by using @nyan.repeat_forever, like this:

cat = nyan.new_text('=^.^=')

@nyan.repeat_forever
def do():
    cat.turn(10)  

The above code will make the cat turn around forever. Sprites have other commands that you can see in the next section called Sprite Commands.

@nyan.when_program_starts

To make some code run just at the beginning of your project, use @nyan.when_program_starts, like this:

cat = nyan.new_text('=^.^=')

@nyan.when_program_starts
def do():
    cat.turn(180)  

This will make the cat turn upside down instantly when the program starts.

await nyan.sleep(seconds=1)

To run code after a waiting period, you can use the await nyan.sleep() command like this:

cat = nyan.new_text('=^.^=')

@nyan.when_program_starts
async def do():
    cat.turn(180)  
    await nyan.sleep(seconds=2)
    cat.turn(180)  

This will make the cat turn upside down instantly when the program starts, wait 2 seconds, then turn back up again.

nyan.broadcast()

You can use nyan.broadcast() to broadcast an event that can be picked up by an event listener.

@nyan.repeat_forever
def do():
    nyan.broadcast('marco')

@nyan.when_event_recieved()

To run code in response to a broadcasted event, use @nyan.when_event_recieved(), like this

@nyan.when_event_recieved('marco')
def do():
    print('polo')

@nyan.foreach_sprite()

attaches a script to each sprite passed or in the case a tag is passed, for each sprite that has the given tag. Should be used in conjunction with @nyan.repeat_forever and @nyan.when_program_starts decorators. Example:

@nyan.repeat_forever
@nyan.foreach_sprite(player1, player2, player3, player4)
async def animate_player(player):
    next_frame(player)
    await nyan.sleep(player.frameTime)

@nyan.repeat_forever
@nyan.foreach_sprite(tag='player-missile')
async def propel_missile(missile):
    missile.move(25)

Sprite Commands

Simple commands

Sprites (images and text) have a few simple commands:

• sprite.move(10) — moves the sprite 10 pixels in the direction it's facing (starts facing right). Use negative numbers (-10) to go backward.
• sprite.move(10, direction=45) — moves the sprite 10 pixels at an angle specified by the direction.
• sprite.turn(20) — Turns the sprite 20 degrees counter-clockwise. Use negative numbers (-20) to turn the other way.
• sprite.go_to(other_sprite) — Makes sprite jump to another sprite named other_sprite's position on the screen. Can also be used to make the sprite follow the mouse: sprite.go_to(nyan.mouse).
• sprite.go_to(x=100, y=50) — Makes sprite jump to x=100, y=50 (right and up a little).
• sprite.point_towards(other_sprite) — Turns sprite so it points at another sprite called other_sprite.
• sprite.point_towards(x=100, y=50) — Turns sprite so it points toward x=100, y=50 (right and up a little).
• sprite.hide() — Hides sprite. It can't be clicked when it's hidden.
• sprite.show() — Shows sprite if it's hidden.
• sprite.add_tag('car') — Adds a tag named car to the sprite. Tagging a sprite adds it to a group that can be fetched later by other functions.
• sprite.remove_tag('car') — removes the car tag from the sprite
• sprite.clone() — Makes a copy or clone of the sprite and returns it.
• sprite.remove() — Removes a sprite from the screen permanently. Calling sprite commands on a removed sprite won't do anything.

Properties

Sprites also have properties that can be changed to change how the sprite looks. Here they are:

• sprite.x — The sprite's horizontal position on the screen. Positive numbers are right, negative numbers are left. The default is 0.
• sprite.y — The sprite's vertical position on the screen. Positive numbers are up, negative numbers are down. The default is 0.
• sprite.size — How big the sprite is. The default is 100, but it can be made bigger or smaller.
• sprite.angle — How much the sprite is turned. Positive numbers are counter-clockwise. The default is 0 degrees (pointed to the right).
• sprite.transparency — How see-through the sprite is from 0 to 100. 0 is completely see-through, 100 is not see-through at all. The default is 100.
• sprite.brightness - How bright or dim the sprite is from -100 to 100. -100 is completely dark, 100 is white. The default is 0.
• sprite.is_hidden — True if the sprite has been hidden with the sprite.hide() command. Otherwise False.
• sprite.is_shown — True if the sprite has not been hidden with the sprite.hide() command. Otherwise False.
• sprite.left — The x position of the left-most part of the sprite.
• sprite.right — The x position of the right-most part of the sprite.
• sprite.top — The y position of the top-most part of the sprite.
• sprite.bottom — The y position of the bottom-most part of the sprite.

Image-sprite-only properties:

• sprite.image — The filename of the image shown.

Text-sprite-only properties:

• text.text — The displayed text content.
• text.font — The filename of the font e.g. 'Arial.ttf'. The default is None, which will use a built-in font.
• text.font_size — The text's size. The default is 50 (pt).
• text.color — The text's color. The default is black.

Box-sprite-only properties:

• box.color — The color filling the box. The default is black.
• box.width — The width of the box. The default is 100 pixels.
• box.height — The height of the box. The default is 200 pixels.
• box.border_width — The width of the box's border, the line around it. The default is 0.
• box.border_color — The color of the box's border. The default is 'light blue'.

If the box has a border, the box's total width, including the border, will be the width defined by the width property.

Circle-sprite-only properties:

• circle.color — The color filling the circle. The default is black.
• circle.radius — How big the circle is, measured from the middle to the outside. The default is 100 pixels, making a 200-pixel-wide circle.
• circle.border_width — The width of the circle's border, the line around it. The default is 0.
• circle.border_color — The color of the circle's border. The default is 'light blue'.

If the circle has a border, the circle's total width, including the border, will be the width defined by the radius property.

These properties can changed to do the same things as the sprite commands above. For example,

sprite.go_to(other_sprite)

# the line above is the same as the two lines below
sprite.x = other_sprite.x
sprite.y = other_sprite.y

You can change the properties to animate the sprites. The code below makes the cat turn around.

cat = nyan.new_text('=^.^=')

@nyan.repeat_forever
def do():
    cat.angle += 1
    # the line above is the same as cat.turn(1)

Other info

Sprites also have some other useful info:

• sprite.width — Gets how wide the sprite is in pixels.
• sprite.height — Gets how tall the sprite is in pixels.
• sprite.distance_to(other_sprite) — Gets the distance in pixels to other_sprite.
• sprite.distance_to(x=100, y=100) — Gets the distance to the point x=100, y=100.
• sprite.is_touching(other_sprite) — Returns True if sprite is touching the other_sprite. Otherwise False.
• sprite.is_touching(point) — Returns True if the sprite is touching the point (anything with an x and y coordinate). For example: sprite.is_touching(nyan.mouse)

Mouse Commands

Working with the mouse in Nyan is easy. Here's a simple program that points a sprite at the mouse:

arrow = nyan.new_text('-->', font_size=100)

@nyan.repeat_forever
def do():
    arrow.point_towards(nyan.mouse)

nyan.mouse has the following properties:

• nyan.mouse.x — The horizontal x position of the mouse.
• nyan.mouse.y — The vertical y position of the mouse.
• nyan.mouse.is_clicked — True if the mouse is clicked down, or False if it's not.
• nyan.mouse.is_touching(sprite) — Returns True if the mouse is touching a sprite, or False if it's not.

@sprite.when_clicked

Probably the easiest way to detect clicks is to use @sprite.when_clicked.

In the program below, when the face is clicked it changes for 1 second then turns back to normal:

face = nyan.new_text('^.^', font_size=100)

@face.when_clicked
async def do():
    face.text = '*o*'
    await nyan.sleep(seconds=1)
    face.text = '^.^'

@nyan.when_sprite_clicked()

If you wanted to run the same code when multiple sprites are clicked, you can use @nyan.when_sprite_clicked():

face1 = nyan.new_text('^.^', x=-100, font_size=100)
face2 = nyan.new_text('^_^', x=100, font_size=100)

@nyan.when_sprite_clicked(face1, face2) # takes as many sprites as you want
async def do(sprite):
    starting_words = sprite.text
    sprite.text = '*o*'
    await play.sleep(seconds=1)
    sprite.text = starting_words

@nyan.mouse.when_clicked or @nyan.when_mouse_clicked

To run code when the mouse is clicked anywhere, use @nyan.mouse.when_clicked or @nyan.when_mouse_clicked (they do the same exact thing).

In the code below, when a click is detected, the text will move to the click location and the coordinates will be shown:

text = nyan.new_text('0, 0')

@nyan.mouse.when_clicked
def do():
    text.text = f'{nyan.mouse.x}, {nyan.mouse.y}'
    text.go_to(nyan.mouse)

@nyan.mouse.when_click_released or @nyan.when_mouse_click_released

To run code when the mouse button is released, use @nyan.mouse.when_click_released @nyan.when_mouse_click_released (they do the same exact thing).

In the code below, the cat can be dragged around when it's clicked by the mouse:

cat = nyan.new_text('=^.^= drag me!')
cat.is_being_dragged = False

@cat.when_clicked
def do():
    cat.is_being_dragged = True

@nyan.mouse.when_click_released
def do():
    cat.is_being_dragged = False

@nyan.repeat_forever
def do():
    if cat.is_being_dragged:
        cat.go_to(nyan.mouse)

Keyboard Commands

nyan.key_is_pressed()

You can use nyan.key_is_pressed() to detect keypresses.

In the code below, pressing the arrow keys or w/a/s/d will make the cat go in the desired direction.

cat = nyan.new_text('=^.^=')

@nyan.repeat_forever
def do():
    if nyan.key_is_pressed('up', 'w'):
        cat.y += 15
    if nyan.key_is_pressed('down', 's'):
        cat.y -= 15

    if nyan.key_is_pressed('right', 'd'):
        cat.x += 15
    if nyan.key_is_pressed('left', 'a'):
        cat.x -= 15

@nyan.when_key_pressed()

You can use @nyan.when_key_pressed() to run code when specific keys are pressed.

In the code below, pressing the space key will change the cat's face, and pressing the enter key will change it to a different face.

cat = nyan.new_text('=^.^=')

@nyan.when_key_pressed('space', 'enter') # if either the space key or enter key are pressed...
def do(key):
    if key == 'enter':
        cat.text = '=-.-='
    if key == 'space':
        cat.text = '=*_*='

@nyan.when_any_key_pressed

If you just want to detect when any key is pressed, you can use @nyan.when_any_key_pressed.

In the code below, any key you press will be displayed on the screen:

text = nyan.new_text('')

@nyan.when_any_key_pressed
def do(key):
    text.text = f'{key} pressed!'

@nyan.when_key_released()

Exactly like @nyan.when_key_pressed() but runs the code when specific keys are released.

In the code below, text will appear on screen only if the up arrow is pressed.

text = nyan.new_text('')

@nyan.when_key_released('up')
async def do(key):
    text.text = 'up arrow released!'
    await nyan.sleep(seconds=1)
    text.text = ''

@nyan.when_any_key_released

Exactly like @nyan.when_any_key_pressed but runs the code when any key is released.

In the code below, the name of the most recently released key will show up on screen.

text = nyan.new_text('')

@nyan.when_any_key_pressed
def do(key):
    text.text = f'{key} key released!''

Audio Commands

nyan.new_sound()

meow = nyan.new_sound(sound='meow.wav')

This will load a sound file with .wav extension and makes it ready to be played. This function should be mainly used for sound effects. You can get sounds from online sites like Freesound or you can generate your own using Bfxr.

meow.play()

This will play the loaded sound file.

meow = nyan.new_sound(sound='meow.wav')

@nyan.when_key_pressed('space')
def do():
    meow.play()

nyan.music.play()

To play an mp3 file in the background, use nyan.music.play(), like this

nyan.music.play('William Tell Overture Finale.mp3', loop=True)

await nyan.music.play_until_done()

This is the same as nyan.music.play(), but waits for the music to finish before continuing

@nyan.when_program_starts
async def do():
    await nyan.music.play_until_done('William Tell Overture Finale.mp3')
    print('music has ended')

nyan.music.pause()

Pauses the currently playing music

@nyan.when_program_starts
async def do():
    nyan.music.play('William Tell Overture Finale.mp3')
    await nyan.sleep(seconds=5)
    nyan.music.pause()

nyan.music.unpause()

Resumes the paused music

@nyan.when_program_starts
async def do():
    nyan.music.play('William Tell Overture Finale.mp3')
    await nyan.sleep(seconds=5)
    nyan.music.pause()
    await nyan.sleep(seconds=5)
    nyan.music.unpause()

nyan.music.stop()

Stops the currently playing music

@nyan.when_program_starts
async def do():
    nyan.music.play('William Tell Overture Finale.mp3')
    await nyan.sleep(seconds=5)
    nyan.music.stop()

nyan.music.volume

You can use nyan.music.volume to get or set the current volume which ranges from 0 to 100. The default is 100

@nyan.when_program_starts
async def do():
    nyan.music.play('William Tell Overture Finale.mp3')
    await nyan.sleep(seconds=5)
    nyan.music.volume = 70

Other Useful Commands

nyan.screen

The way to get information about the screen. nyan.screen has these properties:

• nyan.screen.width - Defaults to 800 (pixels total). Changing this will change the screen's size.
• nyan.screen.height - Defaults to 600 (pixels total). Changing this will change the screen's size.
• nyan.screen.left - The x coordinate for the left edge of the screen.
• nyan.screen.right - The x coordinate for the right edge of the screen.
• nyan.screen.top - The y coordinate for the top of the screen.
• nyan.screen.bottom - The y coordinate for the bottom of the screen.

nyan.get_sprites()

Returns a list of all the sprites (images, shapes, text) in the program. Takes an optional tag parameter that can be used to get all sprites that have a give tag.

nyan.random_number()

A function that makes random numbers.

If two whole numbers are given, nyan.random_number() will give a whole number back:

nyan.random_number(lowest=0, highest=100)

# example return value: 42

(You can also do nyan.random_number(0, 100) without lowest and highest.)

If non-whole numbers are given, non-whole numbers are given back:

nyan.random_number(0, 1.0)
# example return value: 0.84

nyan.random_number() is also inclusive, which means nyan.random_number(0,1) will return 0 and 1.

nyan.random_color()

Returns a random RGB color, including white and black.

nyan.random_color()
# example return value: (201, 17, 142)

Each value varies from 0 to 255.

nyan.random_position()

Returns a random position on the screen. A position object has an x and y component.

text = nyan.text('WOO')
@nyan.repeat_forever
def do():
    text.go_to(nyan.random_position())

    # the above is equivalent to:
    position = nyan.random_position()
    text.x = position.x
    text.y = position.y

nyan.random_item()

Picks a random item from a list. The passed list should contain at least one item.

text = nyan.text('WOO')
@nyan.repeat_forever
def do():
    random_angle = nyan.random_item([0, 90, 180, 270])
    text.angle = random_angle

nyan.new_timer()

Creates a timer. Useful for keeping track of time and for doing animations.

timer = new_timer()

Once a timer is created, it will have the following commands and properties:

• timer.reset() — resets the timer
• timer.seconds — time elapsed in seconds since creation or last reset
• timer.milliseconds — time elapsed in milliseconds since creation or last reset

nyan.clamp()

Keeps a number between two values. Useful for constraining a sprite to a limited area.

player = nyan.text('>')

@nyan.repeat_forever
def do():
    if nyan.key_is_pressed('right'):
        player.x += 1
    if nyan.key_is_pressed('left'):
        player.x -= 1
    if nyan.key_is_pressed('up'):
        player.y += 1
    if nyan.key_is_pressed('down'):
        player.y -= 1

    player.x = clamp(player.x, -400, 400)
    player.x = clamp(player.y, -300, 300)

Packaging Nyan Programs

Nyan comes with a packager that can be used to create stand-alone executables that can be shared with other people without them having to install Python on their computers. To use it, run the following in your terminal

nyan-packager python_file

This will create an executable file with other stuff in a dist folder inside your project. You can change the icon of the executable with --icon icon_file option. If you would like to have a less cluttered output, you can use --onefile flag to create a single executable + your assets folder.

What's with all this async/await stuff? Is this Python?

Yes, this is Python! Python added async and await as special keywords in Python 3.7. It's part of the asyncio module.

Using async functions means we can use the await nyan.sleep() function, which makes some code a lot simpler and appear to run in-parallel, which new programmers find intuitive.

import nyan

cat = nyan.new_text('=^.^=')

# this code block uses async so it can use the 'await nyan.sleep()' function
@nyan.repeat_forever
async def change_bg():
    nyan.set_backdrop('pink')
    await nyan.sleep(seconds=1)

    nyan.set_backdrop('purple')
    await nyan.sleep(seconds=1)

    nyan.set_backdrop('light blue')
    await nyan.sleep(seconds=1)

# this code block doesn't need async because it doesn't have `await nyan.sleep()`
@nyan.repeat_forever
def do():
    cat.turn(1)

nyan.start_program()

In the above program, the backdrop will change and the cat will appear to turn at the same time even though the code is running single-threaded.

The async keyword isn't necessary to write unless you want to use await functions. If you try to use an await command inside a non-async function, Python will show you an error like this:

  File "example.py", line 31
    await nyan.sleep(seconds=1)
    ^
SyntaxError: 'await' outside async function

To fix that error, just put async before def.

If you don't understand any of this, it's generally safe to just include async before def.