In coolbutuseless/ggthreed: Threed Geoms and Stats for Ggplot2

suppressPackageStartupMessages({
  library(dplyr)
  library(ggplot2)
  library(threed)
  library(ggthreed)
})


knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

In this vignette, threed is used to generate multiple anaglyph images which are then stitched together into an animation.

Configure plot

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Set up plotting parameters
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
obj             <- threed::mesh3dobj$icosahedron
nframes         <- 60
angles          <- seq(0, 2*pi, length.out = nframes + 1) %>% head(-1)
camera_to_world <- threed::look_at_matrix(eye = c(5, 0, 0), at = c(0, 0, 0))
world_to_camera <- threed::invert_matrix(camera_to_world)

Helper function

Helper function

1. Rotates given object
2. Transforms to camera space and performs perspective projection
3. Convert to data.frame and add shading
4. Creates plot using ggplot + geom_polygon

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#' Create a plot of a rotated object
#'
#' @param obj object to rotate
#' @param world_to_camera  World-to-camera transformation
#' @param xangle,yangle,zangle Angle of rotation around the x,y,z axes
#' @param view_size adjust plot view size
#'
#' @return rotated + projected data.frame of object
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
plot_rotated_obj <- function(obj, world_to_camera, xangle = 0, yangle = xangle + pi/2, zangle = xangle * 2, view_size = 0.3) {

  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # Rotate the object and apply transformations
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  obj_rot <- obj %>%
    rotate_by(angle = xangle, v = vec3(x = 1)) %>%
    rotate_by(angle = yangle, v = vec3(y = 1)) %>%
    rotate_by(angle = zangle, v = vec3(z = 1)) %>%
    transform_by(world_to_camera) %>%
    perspective_projection(n=1, f=5) %>%
    identity()

  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # Explicitly convert to a data.frame and apply some easy face shading to
  # mimic a light source above and to the right of the object
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  obj_df <- as.data.frame(obj_rot) %>% 
    subset(!hidden) %>%
    transform(shade = (fny + fnx) / 2)

  # print(sort(obj_df$z))

  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  # ggplot of the object
  #~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  p <- ggplot(obj_df, aes(x, y)) +
    geom_polygon(aes(group = zorder, z = z), fill = NA, alpha = 0.5,
                 stat = 'anaglyph', zscale = 0.03, zoffset = -1.9, zinvert = FALSE) +
    theme_void() +
    theme(legend.position = 'none') +
    coord_equal(xlim = c(-view_size, view_size), y = c(-view_size, view_size)) +
    NULL

  p
}

Test Plot of a Single Frame

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Test plot
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
plot_rotated_obj(obj, world_to_camera, xangle = angles[1], view_size = 0.25)

Create Plot for Every Angle and Combine into GIF

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Create a png_file for every angle
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
png_files <- seq_along(angles) %>% purrr::map_chr(function(i) {
  cat("."); flush.console()
  p        <- plot_rotated_obj(obj, world_to_camera, xangle = angles[i], view_size = 0.25)
  png_file <- glue::glue("{tempdir()}/{i}.png")
  ggsave(png_file, p, width=8, height=8, dpi = 75)
  png_file
})


#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Use {gifski} to create the animation
#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
gif_file <- gifski::gifski(
  png_files, gif_file = "vignettes/gif/animated-anaglyph.gif",
  width = 400, height = 400, delay = 0.1
)

coolbutuseless/ggthreed documentation built on May 16, 2019, 7:14 p.m.