Error(s) in re-building vignettes:
--- re-building 'models-from-other.Rmd' using rmarkdown
trying URL 'http://ryantimpe.com/files/mf_unicorn.PNG'
Warning in download.file("http://ryantimpe.com/files/mf_unicorn.PNG", demo_img,  :
  InternetOpenUrl failed: 'The server name or address could not be resolved'
Quitting from lines 34-41 (models-from-other.Rmd) 
Error: processing vignette 'models-from-other.Rmd' failed with diagnostics:
cannot open URL 'http://ryantimpe.com/files/mf_unicorn.PNG'
--- failed re-building 'models-from-other.Rmd'

--- re-building 'models-from-program.Rmd' using rmarkdown
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
--- finished re-building 'models-from-program.Rmd'

--- re-building 'models-from-tables.Rmd' using rmarkdown
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
--- finished re-building 'models-from-tables.Rmd'

--- re-building 'models-piece-type.Rmd' using rmarkdown
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
--- finished re-building 'models-piece-type.Rmd'

--- re-building 'mosaics.Rmd' using rmarkdown
trying URL 'http://ryantimpe.com/files/mf_unicorn.PNG'
Content type 'image/png' length 277758 bytes (271 KB)
==================================================
downloaded 271 KB

Warning in snapshot3d(paste0(name, ".png")) :
  webshot = TRUE requires the webshot2 package; using rgl.snapshot() instead
--- finished re-building 'mosaics.Rmd'

SUMMARY: processing the following file failed:
  'models-from-other.Rmd'

Error: Vignette re-building failed.
Execution halted