GCC, stringification, and inline GLSL?

Question

I'd like to declare GLSL shader strings inline using macro stringification:

#define STRINGIFY(A)  #A const GLchar* vert = STRINGIFY( #version 120\n attribute vec2 position; void main() {     gl_Position = vec4( position, 0.0, 1.0 ); } ); 

This builds and runs fine using VS2010 but fails to compile on gcc with:

error: invalid preprocessing directive #version 

Is there a way to use stringification like this in a portable manner?

I'm trying to avoid per-line quotes:

const GLchar* vert =  "#version 120\n" "attribute vec2 position;" "void main()" "{" "    gl_Position = vec4( position, 0.0, 1.0 );" "}" ; 

...and/or line continuation:

const GLchar* vert = "\ #version 120\n                                 \ attribute vec2 position;                       \ void main()                                    \ {                                              \     gl_Position = vec4( position, 0.0, 1.0 );  \ }                                              \ "; 

Answer 1

Can you use C++11? If so you could use raw string literals:

const GLchar* vert = R"END( #version 120 attribute vec2 position; void main() {     gl_Position = vec4( position, 0.0, 1.0 ); } )END"; 

No need for escapes or explicit newlines. These strings start with an R (or r). You need a delimiter (I chose END) between the quote and the first parenthesis to escape parenthesis which you have in the code snippet.

Answer 2

Unfortunately, having preprocessor directives in the argument of a macro is undefined, so you can't do this directly. But as long as none of your shaders need preprocessor directives other than #version, you could do something like:

#define GLSL(version, shader)  "#version " #version "\n" #shader  const GLchar* vert = GLSL(120,     attribute vec2 position;     void main()     {         gl_Position = vec4( position, 0.0, 1.0 );     } );