Sorry if this is a "duh" question, but I'd like to use a custom OSL shader, but I'd like it to be sourced from an objective location on my hard drive. How exactly would I go about this in the most efficient manner?
Select the External mode on the script node and set the filepath to your .osl source file or a compiled .oso file. Or, if you put your shaders under the shader search path (see below), you can simply specify the filename.
From the documentation:
The External mode can be used to specify a .osl file from a drive, and this will then be automatically compiled into a .oso file in the same directory. It is also possible to specify a path to a .oso file, which will then be used directly, with compilation done manually by the user. The third option is to specify just the module name, which will be looked up in the shader search path.
The shader search path is located in the same place as the scripts or configuration path, under: