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
attribu         


        

Answer 1

An alternative approach: include a header file, but with a .glsl extension.

For example, I have a file called bar.h.glsl. It exposes my vertex and fragment shader code as raw literals:

#pragma once

namespace bar {

static const char vertex[] = R"(#version 410 core


// ----- vertex shader start -----
layout( location = 0 ) in vec4 vPosition;

uniform float Time;
uniform float Width;

void main()
{
    float x = vPosition.x;
    float y = vPosition.y * Width;
    float yOffset = mix(sin(Time), sin(Time * 0.75), x * 0.5 + 0.5);
    gl_Position = vec4(x, y + yOffset, vPosition.z, vPosition.w);
}
// ------ vertex shader end ------


)";
static const char fragment[] = R"(#version 410 core


// ----- fragment shader start ----
out vec4 fragColor;

void main()
{
    fragColor = vec4(1.0, 1.0, 1.0, 1.0);
}
// ------ fragment shader end -----


)";

}

Then in my source, I simply include the file:

#include "bar.h.glsl"

and access the glsl strings like so:

bool success = barShader.Compile( bar::vertex, bar::fragment );

This way, although I need to overlook a bit of C code in my glsl files, I get the best of glsl syntax highlighting without having to dynamically load the file.

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 );
    }
);

Answer 3

To achieve this purpose I used sed. I have seperate files with GLSL which I edit (with proper syntax highlighting), and in the same time GLSL in inlined in C++. Not very cross platform, but with msys it works under windows.

In C++ code:

const GLchar* vert = 
#include "shader_processed.vert"
;

In Makefile:

shader_processed.vert: shader.vert
    sed -f shader.sed shader.vert > shader_processed.vert

programm: shader_processed.vert main.cpp
    g++ ...

shader.sed

s|\\|\\\\|g
s|"|\\"|g
s|$|\\n"|g
s|^|"|g

Answer 4

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 5

The problem is due to gcc preprocessing macros meant for GLSL. Using standard stringify and escaping preprocessor directives with new lines in GLSL code worked for me.

#define STRINGIFY(A)  #A

const GLchar* vert = STRINGIFY(

\n#version 120\n
\n#define MY_MACRO 999\n

attribute vec2 position;
void main()
{
    gl_Position = vec4( position, 0.0, 1.0 );
}
);