[vim] Implement fast switching between source/header & shaders

vimrc

@@ -196,6 +196,8 @@ for prefix in ['i', 'n', 'v']
         execute prefix . "noremap " . key . " <Nop>"
     endfor
 endfor
+"[Switch quickly between source and header]"
+nnoremap <leader>f :e <C-r>=SwapExtension()<CR><CR>
 
 
 
@@ -242,6 +244,22 @@ function! ChangeScriptMode()
         endif
     endif
 endfunction
+"[Swap file extensions, for example cpp/h]"
+"https://stackoverflow.com/a/22145246"
+function! SwapExtension()
+    let [rest, ext] = [expand('%:r'), expand('%:e')]
+    if ext ==? 'h'
+        let ext = 'cpp'
+    elseif ext ==? 'cpp'
+        let ext = 'h'
+    "swap between vertex and fragment shader"
+    elseif ext ==? 'vsh'
+        let ext = 'fsh'
+    elseif ext ==? 'fsh'
+        let ext = 'vsh'
+    endif
+    return rest . '.' . ext
+endfunction
 
 " Only do this part when compiled with support for autocommands.
 if has("autocmd")