Rcnode.R

library(silicate)

data("wrld_simpl", package = "maptools")
#edges are unique segments (undirected)
#segments are directed instances of edges, belonging to arcs/ways or feature boundaries
library(silicate)
library(sf)
x <- PATH(st_as_sf(wrld_simpl))
#x <- PATH(minimal_mesh)


arcs <- sc_arc(x)

## we now need a generic PATH constructor
## we have unique vertices
xarc <- x
xarc$path_link_vertex <- transmute(arcs, vertex_, path_ = arc_)
xarc$path <- distinct(xarc$path_link_vertex, path_) %>% 
  mutate(object_ = path_)
xarc$object <- tibble(object_ = xarc$path$object_)

## now we want segments, so we have the path_identifier
## (the segments are already normalized in arc form)
edges <- sc_segment(xarc)
from <- edges %>% transmute(vertex_ = .vertex0) %>% 
  inner_join(x[["vertex"]]) %>% 
  transmute(xfr  = x_, yfr = y_)
to <- edges %>% transmute(vertex_ = .vertex1, path_) %>% 
  inner_join(x[["vertex"]]) %>% 
  transmute(xto  = x_, yto = y_, col = stringr::str_sub(viridis::viridis(nrow(xarc$path))[factor(path_)], 1, 7), lwd = 0.5) 

scale <- 4
offset <- 180
svgplot_lines(bind_cols(from, to) %>% mutate(xfr = offset + xfr * scale, 
                                             yfr = offset + yfr * scale, 
                                             xto = offset + xto * scale, 
                                             yto = offset + yto * scale), "b.html")