gganimate with sprites

Sprites

A sprite is a 2d bitmap often used by games to represent objects. A number of sprites displayed in sequence creates an animation.

Puzzle bobble sprite extraction

• Grab a sprite sheet for your favourite game from spriters resource
• I will be using a Bubble Bobble dinosaur
• Work out how to cut out sprites by subsetting the sheet of sprites

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Not going to directly link in to script to avoid hitting server
# https://www.spriters-resource.com/resources/sheets/12/12593.png
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sprite_sheet <- png::readPNG("12593.png")

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Set up the extraction parameters
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Nframes       <- 16      # number of frames to extract
width         <- 28      # width of a frame
sprite_frames <- list()  # storage for the extracted frames

# Not equal sized frames in the sprite sheet. Need to compensate for each frame
offset <- c(3, 4, 6, 7, 7, 6, 5, 5, 6, 6, 7, 7, 7, 6, 7, 8)

# Manually extract each frame
for (i in seq(Nframes)) {
  sprite_frames[[i]] <- sprite_sheet[13:40, (width*(i-1)) + (1:width) + offset[i], 1:3]
}

# Test plot
plot(as.raster(sprite_frames[[15]]), interpolate=FALSE)

Convert sprites to data.frames

• Convert the sprite to a data.frame of values for geom_tile()
• Remove the background colour
• Calculate a lookup table of colours to use with scale_fill_manual
• Stack all the individual frames together

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Function to convert a sprite frame to a data.frame
# and remove any background pixels i.e. #82ABE7
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sprite_frame_to_df <- function(frame) {
  plot_df <- data_frame(
    fill  = as.vector(as.raster(frame)),
    x = rep(1:width, width),
    y = rep(width:1, each=width)
  ) %>%
    filter(fill != '#82ABE7')
}

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Convert all sprite frames to sprite data.frames
# and set the 'idx' column to the frame number
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sprite_dfs <- sprite_frames %>%
  map(sprite_frame_to_df) %>%
  imap(~mutate(.x, idx=.y))

Warning: `data_frame()` is deprecated, use `tibble()`.
This warning is displayed once per session.

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Work out the spirte colours for scale_fill_manual
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fill_manual_values <- unique(sprite_dfs[[1]]$fill)
fill_manual_values <- setNames(fill_manual_values, fill_manual_values)


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Stack all the sprites into a mega data.frame
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mega_df <- dplyr::bind_rows(sprite_dfs)

ggplot - facet-in-space

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Create the basic ggplot object
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p <- ggplot(mega_df, aes(x, y, fill=fill)) +
  geom_tile(width=0.9, height=0.9) +
  coord_equal(xlim=c(1, width), ylim=c(1, width)) +
  scale_fill_manual(values = fill_manual_values) +
  theme_bw() +
  theme(legend.position = 'none')


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Facet by time
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
p +
  facet_wrap(~idx)

gganimate - facet-in-time

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Facet by time with gganimate
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
panim <- p +
  transition_manual(idx, seq_along(sprite_frames)) +
  labs(title = "gganimate bubble bobble")


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Create and save animation
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gganimate::animate(panim, fps=8, width=400, height=400)

nframes and fps adjusted to match transition

# gganimate::anim_save("bubble_bobble.gif")