tiling.R

library(grid)

rect <- function(size, rot_deg) {
  theta <- (c(1 / 4, 3 / 4, 5 / 4, 7 / 4) - rot_deg / 360) * pi
  rectGrob(x = size * sqrt(2) * sin(theta),
           y = size * sqrt(2) * cos(theta))
}

size <- unit(100, "points")
x_orig <- unit(0.5, "npc")
y_orig <- unit(0.5, "npc")

gp1 <- gpar(col = "darkgreen", lwd = 2.7)
gp2 <- gpar(col = "blue",
            fill = "blue",
            alpha = 0.2)

draw <- function(angle) {
  angle <- angle %% 180

  # flip when angle is larger than 45
  if (angle <= 45) {
    d <- size / cos(pi * angle / 180)     # distance between two rectangles
    size1 <- size                         # size of main rectangles
    size2 <- size * tan(pi * angle / 180) # size of complement rectangles
  } else {
    d <- size / cos(pi * (90 - angle) / 180)
    size1 <- size / tan(pi * angle / 180)
    size2 <- size
  }
  
  d1 <- d     # distance between main rectangles
  d2 <- d / 2 # distance between complement rectangles
  
  grid.newpage()
  
  # draw main rectangles
  
  idx <- expand.grid(x = -2:2, y = -2:2)
  for (i in seq_len(nrow(idx))) {
    vp <- viewport(
      x = x_orig + d1 * idx[i, "x"],
      y = y_orig + d1 * idx[i, "y"],
      width = size1,
      height = size1,
      angle = angle
    )
    
    grid.draw(rectGrob(gp = gp1, vp = vp))
  }
  
  # draw complement rectangles
  
  idx2 <- expand.grid(x = c(-5L, -3L, -1L, 1L, 3L, 5L), y = c(-5L, -3L, -1L, 1L, 3L, 5L))
  for (i in seq_len(nrow(idx2))) {
    vp <- viewport(
      x = x_orig + d2 * idx2[i, "x"],
      y = y_orig + d2 * idx2[i, "y"],
      width = size2,
      height = size2,
      angle = angle
    )
    
    grid.draw(rectGrob(gp = gp2, vp = vp))
  }
  
}

d <- tempfile()
dir.create(d)
ragg::agg_png(file.path(d, "plot%03d.png"))

for (i in 0:180) {
  draw(i * 1.0)
}
dev.off()

gifski::gifski(list.files(d, full.names = TRUE), delay = 0.01)