R script for generating animated Clifford attractors

clifford_attractor_animation.R

library(Rcpp)
library(ggplot2)
library(dplyr)
library(foreach)
library(doParallel)
registerDoParallel(parallel::detectCores())

pic_dir <- "pics"
output_video <- "output.mp4"

opt = theme(legend.position  = "none",
            panel.background = element_rect(fill="black"),
            plot.margin = margin(0, 0, -8, -8, unit = "pt"),
            axis.ticks       = element_blank(),
            panel.grid       = element_blank(),
            axis.title       = element_blank(),
            axis.text        = element_blank())

cppFunction('DataFrame createTrajectory(int n, double x0, double y0, 
            double a, double b, double c, double d) {
            // create the columns
            NumericVector x(n);
            NumericVector y(n);
            x[0]=x0;
            y[0]=y0;
            for(int i = 1; i < n; ++i) {
            x[i] = sin(a*y[i-1])+c*cos(a*x[i-1]);
            y[i] = sin(b*x[i-1])+d*cos(b*y[i-1]);
            }
            // return a new data frame
            return DataFrame::create(_["x"]= x, _["y"]= y);
            }
            ')

# attractor parameters
a=-1.24458046630025
b=-1.25191834103316 
c=-1.81590817030519 
d=-1.90866735205054

# video settings
fps <- 60
duration_secs <- 30
frac_change <- 2 # fractional change in "a" param over course of video

max_a <- a + (a*frac_change/2)
min_a <- a - (a*frac_change/2)

a_vec <- seq(from = min_a, to = max_a, by = (a*frac_change)/((fps-1)*duration_secs)) 

# loop over parameter, write out png
foreach (i = 1:length(a_vec)) %dopar% {
  filename <- file.path(pic_dir, paste0("pic_", i, ".png"))
  df = createTrajectory(10000000, 0, 0, a_vec[i], b, c, d)
  p <- ggplot(df, aes(x, y)) + geom_point(color = "white", shape = 46, alpha = .3) + opt
  
  ggsave(plot = p, filename = filename, width = 10.8, height = 10.8, dpi = 100)
}

#### FFMPEG ####
command <- paste0("ffmpeg -y -r ", fps, " -f image2 -s 1080x1080 -i ", pic_dir,
                  "/pic_%d.png -vcodec libx264 -crf 25 -pix_fmt yuv420p ", output_video)
system(command = command)

# unlink(pic_dir, recursive = TRUE) # tidy up

pic_606.png

clifford_attractor_animation.R

Inspired by this blog post. Above script creates this video.

(Pic_606.png is one frame of the video)