1. Plot

The click_pixel() function opens an interactive plot. If n_state = 3, for example, then each pixel will cycle through three states as you keep clicking it. You’re returned a matrix of these values when you hit Esc.

That was enough for {tamRgo}: I turned a binary matrix into a 1-bit sprite. But wouldn’t it be good—fundamental!—to be able to plot the matrix as an image with user-specified colours? So I made draw_pixels().

I’ve added a three-state matrix, blue, into the package as an example dataset. Let’s plot it with simple colours:

draw_pixels(
  m = pixeltrix::blue, 
  colours = c("white", "#879afb", "gray20")
)

Of course, it’s the subtly-coloured player character from Pokémon Blue (1996) as seen on the Nintendo Game Boy Color.

2. Animate

Naturally, you could use click_pixels() and draw_pixels() to generate several images and combine them as ‘frames’ of an animation. Why not have a function that does this automatically?

So that’s what I did:

• frame_pixels() calls click_pixels() and adds the output as the first element of a list, then it passes that matrix into edit_pixels() as the template for the next frame (and so on until you choose to stop making frames)
• gif_pixels() takes the list of matrices created by frame_pixels() and draws, combines and writes them to a gif

I’ve prepared pixeltrix::mario as an example of an output from frame_pixels(). It contains each of three frames that comprise Mario’s walk cycle from Super Mario Bros on the NES.

Here’s what the console output looked like when I made mario:

mario <- frame_pixels(
  n_rows   = 16,
  n_cols   = 16,
  n_states = 4  # background + 3 colours
)
# Click squares in the plot window. Press <Esc> to end.
# Add a frame? y/n: y
# Click squares in the plot window. Press <Esc> to end.
# Current frame count: 2
# Add a frame? y/n: y
# Click squares in the plot window. Press <Esc> to end.
# Current frame count: 3
# Add a frame? y/n: n
# Final frame count: 3

You can see there’s interactivity; the user is prompted to add another frame with Add a frame? y/n:, where y will let you create a new frame and n will stop the process and return the list of matrices.

And so you can see it’s a list of three matrices:

str(mario)

## List of 3
##  $ : int [1:16, 1:16] 0 0 0 0 0 0 0 0 1 1 ...
##  $ : int [1:16, 1:16] 0 0 0 0 0 0 0 0 0 0 ...
##  $ : int [1:16, 1:16] 0 0 0 0 0 0 0 0 0 0 ...

You can then convert the list to a gif with gif_pixels(), which engifs the frames using {gifski}.¹

gif_pixels(
  frames = mario,
  colours = c(
    "white",    # background
    "#FDA428",  # skin (yellowish)
    "#FC0D1B",  # overalls/hat (red)
    "#A32B2E"   # hair, eyes, shirt, boots (brown)
  ),
  file = "mario.gif",
  delay = 0.15  # passed via dots to gifski::save_gif()
)
# Inserting image 3 at 0.30s (100%)...
# Encoding to gif... done!
# [1] "mario.gif"

And if we open that file:

Yahoooooo, created entirely with R. Noice.

Pix n mix

So {pixeltrix} finally got a couple of nice-to-have (well, must-have) functions. This is enough for me to continue just messing around with it as a novelty².

I mean, come on: animated pixelart created in an interactive R plot window? Why? I mean, er… wow!

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