R6 Fractal Tree

r6_fractal_tree.R

library(R6)
library(ggplot2)
library(uuid)
options(stringsAsFactors = FALSE)

branch_base = R6Class('branch_base',
                      public = list(
                          start_x = NA_integer_,
                          start_y = NA_integer_,
                          end_x = NA_integer_,
                          end_y = NA_integer_,
                          type = NA_character_,
                          id = NA_character_,
                          branch_color = NA_character_
                        ),  # public
                      
                      active = list(
                        df = function() {
                            x = c(self$start_x, self$end_x)
                            y = c(self$start_y, self$end_y)
                            
                            data.frame(x = x, y = y, 
                                       type = self$type, 
                                       id = self$id,
                                       branch_color = self$branch_color)
                          }
                        )  # active
                      )  # branch_base

trunk = R6Class('trunk',
                inherit = branch_base,
                public = list(
                  initialize = function(len = 10, branch_color = '#000000') {
                      self$start_x = 0
                      self$start_y = 0
                      self$end_x = 0
                      self$end_y = len
                      self$type = 'trunk'
                      self$branch_color = branch_color
                      
                      self$id = uuid::UUIDgenerate()
                    }
                  )  # public 
                )  # trunk

branch = R6Class('branch',
                 inherit = branch_base,
                 public = list(
                   initialize = function(x, y, len = 5, theta = 45, 
                                         type = NA_character_, branch_color='#000000') {
                       dy = sin(theta) * len
                       dx = cos(theta) * len
                       
                       self$start_x = x
                       self$start_y = y
                       self$end_x = x + dx
                       self$end_y = y + dy
                       
                       self$type = type
                       self$id = uuid::UUIDgenerate()
                       self$branch_color = branch_color
                     }
                   )  # public
                 )  # branch

fractal_tree = R6Class('fractal_tree',
                       public = list(
                         delta_angle = NA_real_,
                         len_decay = NA_real_,
                         min_len = NA_real_,
                         branches = data.frame(),
                         branch_left_color = NA_character_,
                         branch_right_color = NA_character_,
                         
                         initialize = function(trunk_len = 10,
                                               delta_angle = pi / 8,
                                               len_decay = 0.7,
                                               min_len = 0.25,
                                               trunk_color = '#000000',
                                               branch_left_color = '#000000',
                                               branch_right_color = '#adadad') {
                             self$delta_angle = delta_angle
                             self$len_decay = len_decay
                             self$min_len = min_len
                             self$branch_left_color = branch_left_color
                             self$branch_right_color = branch_right_color
                             
                             self$branches = trunk$new(trunk_len, trunk_color)$df
                             
                             private$grow_branches(0, trunk_len,
                                                   len = trunk_len * len_decay,
                                                   angle_in = pi / 2)
                           },  # initialize
                         
                         plot = function() {
                             ggplot(tree$branches, aes(x, y, group = id, color=branch_color)) +
                               geom_line() +
                               geom_point(color = 'darkgreen', size=0.5) +
                               scale_color_identity() +
                               guides(color = FALSE, linetype = FALSE) +
                               theme_void()
                           }
                         ), # public
                       
                       private = list(
                         grow_branches = function(start_x, start_y, 
                                                  len = 1,
                                                  angle_in = pi / 2,
                                                  parent_type = NA, 
                                                  parent_color = NA) {
                             if (len >= self$min_len) {
                               l_type = if (!is.na(parent_type)) parent_type else 'left'
                               r_type = if (!is.na(parent_type)) parent_type else 'right'
                               l_color = if (!is.na(parent_color)) parent_color else self$branch_left_color
                               r_color = if (!is.na(parent_color)) parent_color else self$branch_right_color
                               
                               branch_left  = branch$new(start_x, start_y, len, angle_in + self$delta_angle, l_type, l_color)
                               branch_right = branch$new(start_x, start_y, len, angle_in - self$delta_angle, r_type, r_color)
                               
                               self$branches = rbind(self$branches, branch_left$df, branch_right$df)
                               
                               private$grow_branches(branch_left$end_x, 
                                                     branch_left$end_y,
                                                     angle_in = angle_in + self$delta_angle,
                                                     len = len * self$len_decay,
                                                     parent_type = branch_left$type,
                                                     parent_color = branch_left$branch_color)
                               
                               private$grow_branches(branch_right$end_x, 
                                                     branch_right$end_y,
                                                     angle_in = angle_in - self$delta_angle,
                                                     len = len * self$len_decay,
                                                     parent_type =  branch_right$type,
                                                     parent_color = branch_right$branch_color)
                             }
                           }  # grow_branches
                         )  # private
                       )  # fractal_tree

tree = fractal_tree$new()
tree$plot()