R/fading.R

In nrennie/aRt: Generative Art with R

#' Fading
#'
#' This function generates a coloured generative art ggplot object using
#' voronoi tiles.
#'
#' @param n_layers Number of layers. Default 6.
#' @param n_points Number of points per layer area. Default 10.
#' @param col_palette Vector of colours. Default "SunsetDark" colour palette
#' from rcartocolor.
#' @param s Seed value. Default 1234.
#' @return A ggplot object.
#' @examples
#' fading()
#' @export

fading <- function(n_layers = 6,
                   n_points = 10,
                   col_palette = rcartocolor::carto_pal(n = 7, "SunsetDark"),
                   s = 1234) {
  plot_data <- withr::with_seed(
    seed = s,
    code = {
      n_points <- n_points * (n_layers:1)
      x_widths <- 2 * (n_layers:1)
      x_lower <- cumsum(2 * (n_layers:1))
      x_upper <- x_lower + x_widths
      y_widths <- 4 * (n_layers:1)
      y_lower <- cumsum(4 * (n_layers:1))
      y_upper <- y_lower + y_widths
      y <- unlist(
        lapply(1:n_layers, function(i) {
          round(
            stats::runif(n_points[i], y_lower[i], y_upper[i]), 1
          )
        })
      )
      x <- round(-0.5 * y + unlist(
        lapply(1:n_layers, function(i) {
          round(
            stats::runif(n_points[i], x_lower[i], x_upper[i]), 1
          )
        })
      ), 1)
      z <- y + stats::rnorm(length(x), 0, 0.5)
      df <- tibble::tibble(x = x, y = y, z = z)
      plot_data <- dplyr::filter(df, !is.na(.data$y))
      plot_data
    }
  )
  p <- ggplot2::ggplot(
    data = plot_data,
    mapping = ggplot2::aes(x = .data$x, y = .data$y, group = -1L)
  ) +
    ggforce::geom_voronoi_tile(ggplot2::aes(fill = z)) +
    ggplot2::coord_cartesian(expand = FALSE) +
    ggplot2::scale_fill_gradientn(colours = rev(col_palette)) +
    theme_aRt("transparent", -0.5)
  return(suppressWarnings(print(p)))
}