I use the glsl syntax highlighting file, it works the first time I load a shader, after that, no highlight, why?

Question

I've a project where I work on OpenGL Shaders.

I downloaded the glsl syntax file and installed it on my computer (a personal folder) and then added the following auto-load line to my .vimrc:

au BufNewFile,BufReadPost   *.shader,*.frag,*.vert,*.fp,*.vp,*.glsl   so $HOME/vim/glsl.vim

When I first load one of my '*.shader' file, I get the syntax highlighting as expect. The second time (i.e. say I loaded two files, I do :n and then :N), the highlighting is non-existent.

The syntax variable is properly set, syntax=glsl, but the text is just plain black on white.

The glsl.vim file has just two things that could cause a problem:

" near the start
if exists("b:current_syntax") && b:current_syntax == "glsl"
  finish
endif

...

" near the end
if !exists("b:current_syntax")
  let b:current_syntax = "glsl"
endif

I tried to remove the && b:current_syntax == "glsl", because other syntax files do not have that. No difference.

Then I tried to remove the if !exists("b:current_syntax") near the end, and again, no difference.

All my other syntax files work as expected, so I'm not too sure why this one would have such a problem. Everything get colors (my .h and .cpp files, CMakeLists.txt, .sh, etc.) except those *.shader files outside of the first load.

Answer 1

I downloaded the glsl syntax file and installed it on my computer (a personal folder)

Where did you install the syntax file? Make sure it's located in your ~/.vim/syntax/ directory.

and then added the following auto-load line to my .vimrc:

The :source command is wrong in this context:

au BufNewFile,BufReadPost   *.shader,*.frag,*.vert,*.fp,*.vp,*.glsl   so $HOME/vim/glsl.vim
                                                                      ^-------------------^
                                                                                ✘

It should be a :setfiletype command:

au BufNewFile,BufReadPost   *.shader,*.frag,*.vert,*.fp,*.vp,*.glsl   setf glsl
                                                                      ^-------^
                                                                          ✔

Have a look at the $VIMRUNTIME/filetype.vim file.