Shady

#pragma shady: import(shader_name)
#pragma shady: import(shader_name.identifier_name)

#pragma shady: macro_begin MACRO_NAME
#pragma shady: macro_end
#pragma shady: inline(shader_name.MACRO_NAME)

#pragma shady: variant(shader_name, [KEYWORD_NAME1], [KEYWORD_NAME2], ...)

The tool is integrated into the compilation process via compiler scripts so you can write reusable shaders inside standard GameMaker shader files with built-in or any other code editor.