rgl displays not showing up #85
Description
I just had a report that the vignettes in rgl are not displaying the graphics properly. They were using R Markdown and markdown::html_format as the output driver, and that stopped working with this commit rstudio/markdown@b4c328d to that package.
For example, this vignette: https://github.com/dmurdoch/rgl/blob/8e12a29031f2b0e52fc204cc1b947fcdabd6bdf0/vignettes/transparency.Rmd should display movable shapes, but it just displays blank blocks now.
Of course, markdown is no longer being maintained so I can't post an issue there, and I tried to follow the instructions to use litedown::html_format instead, with no luck.
I can switch rgl back to using rmarkdown::html_vignette; it still works, but I liked avoiding Pandoc with markdown::html_format, and from the design goals, it seems like litedown should suit me if I can figure out how to get it to work.
I think the things I need to know are necessary changes to knit_print methods and sew methods to work in litedown (and maybe changes to code to detect that I'm in litedown). Are those documented anywhere?