A bit of fun experimenting with tile-based 'gravity' in R

droplet-physics.R

m <- matrix(rep(".", 30), 5, 6)
m[4, c(2:4, 6)] <- "X"
m[3, 2] <- "X"
m[5, 4:6] <- "X"
m[1, 4] <- "o"

matrix(1:140, 20, 7)
m <- pixeltrix::click_pixels(20, 7)
m[which(m == 0)] <- "."
m[which(m == 1)] <- "X"
attributes(m)["colours"] <- NULL
m[1, 4] <- "o"
m

repeat {
  
  cat("\014")
  
  for (row in seq(nrow(m))) {
    cat(m[row, ], "\n", sep = "")
  }
  
  Sys.sleep(1)
  
  droplet_i <- which(m == "o")
  droplet_i_save <- droplet_i
  below_i   <- droplet_i + 1
  
  if (m[below_i] == ".") {
    m[droplet_i] <- "."
    m[below_i]   <- "o"
  }
  
  if (m[below_i] == "X") {
    
    left_i  <- droplet_i - nrow(m)
    right_i <- droplet_i + nrow(m)
    
    is_left_open  <- FALSE
    is_right_open <- FALSE
    
    if (m[left_i] == ".")  is_left_open  <- TRUE
    if (m[right_i] == ".") is_right_open <- TRUE
    
    if (is_left_open & is_right_open) {
      sampled_direction_i <- sample(c(left_i, right_i), 1)
      m[droplet_i] <- "."
      m[sampled_direction_i]   <- "o"
    }
    
    if (is_left_open & !is_right_open) {
      m[droplet_i] <- "."
      m[left_i]    <- "o"
    }
    
    if (!is_left_open & is_right_open) {
      m[droplet_i] <- "."
      m[right_i]   <- "o"
    }
    
  }

  droplet_i <- which(m == "o")
  if (droplet_i == droplet_i_save) break
  
}