Appendix D — Magic Eye

Setup

library(tidyverse) # for data wrangling
library(MetBrewer) # for colour themes
library(ggforce)   # for the stereogram
library(sf)        # for finding the points in a frame

I used to be obsessed with those MagicEye pictures and would waste so much time in the mall staring at them. This one is a bit chaotic, but I like it :)

Code

set.seed(8675309)
t <- seq(0, 2*pi, by=0.1)
t <- c(t, t[[1]]) # append starting value
x = 16*sin(t)^3
y = 13*cos(t)-5*cos(2*t)-2*cos(3*t)-cos(4*t)
frame <- cbind(x, y)

frame_sf <- frame %>%
  list() %>% 
  sf::st_polygon()

cols <- met.brewer("Klimt", 6)

n = 4000
points <- data.frame(
  x = runif(n, min = min(x)-5, max = max(x)+5),
  y = runif(n, min = min(y)-5, max = max(y)+5),
  depth = 0,
  col = sample(cols, n, T)
)

points_sf <- sf::st_as_sf(points, coords = c("x","y"))

## Keeps only the random points that are within the frame
contained <- sf::st_contains(frame_sf, points_sf)
points$depth[contained[[1]]] <- 4

ggplot(points, aes(x, y, depth = depth, color = I(col))) + 
  geom_point(size = 3) +
  facet_stereo(panel.size = 200) +
  theme_void() +
  theme(panel.background = element_rect(color = "black", size = 3))