Drawing a Droste Effect Polygon with ggplot2 3.2.0

droste.R

library(tidyverse)

polygon_values <- tibble(
    id = 1:2,
    value = c(-2, 2)
)

polygon_positions <- tibble(
    id = c(1, 1, 1, 2, 2, 2, 2),
    x = c(1, 2, 3, 5, 6, 7, 6),
    y = c(1, 2, 1, 1.5, 2, 1.5, 1)
)

datapoly <- polygon_values %>%
    left_join(polygon_positions)
datapoly$subid <- 1

# create sub holes within polygons
for(i in 1:3) {
    holes <- datapoly %>%
        filter(subid == i) %>%
        group_by(id, value, subid) %>%
        summarise(x = list(x + 0.5 * (mean(x) - x)),
                  y = list(y + 0.5 * (mean(y) - y))) %>%
        unnest() %>%
        ungroup()
    holes$subid <- i + 1
    datapoly <- rbind(datapoly, holes)
}

p <- ggplot(datapoly, aes(x = x, y = y)) +
    geom_polygon(aes(fill = value, group = id, subgroup = subid),
                 color = "black", show.legend = FALSE) +
    scale_fill_continuous() +
    theme_void()
p