OpenGL GLSL shaders on Mac does not compile

Question

When I try to compile GLSL shaders for my application on Mac, it fails with a version conflict error of the shader:

Error compiling vertex shader:
ERROR: 0:1: '' :  version '130' is not supported

Error compiling shader:
ERROR: 0:1: '' :  version '130' is not supported

The shaders are as such:

Vertex shader:

#version 130

in vec2 in_vPos;
in vec2 in_vTexCoord;

out vec2 s_vTexCoord;

void main()
{
    gl_Position = vec4(in_vPos, 0, 1);
    s_vTexCoord = (in_vTexCoord + vec2(1, 1)) / 2;
}

Fragment shader:

#version 130

in vec2 s_vTexCoord;

out vec4 s_colOut;

uniform sampler2DRect s_texSampler;
uniform vec4 s_colBlend;

void main()
{
    vec4 pixel = texture(s_texSampler, s_vTexCoord * textureSize(s_texSampler));
    s_colOut = s_colBlend * pixel;
}

This is how I initialize my SDL renderer and Glew:

  ren_pRenderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);

  SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
  SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 4);
  glEnable(GL_MULTISAMPLE);

  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
  SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
  SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE | SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);

  SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "1");

  static bool _bInitializedGlew = false;
  if(!_bInitializedGlew) {
    glewExperimental = GL_TRUE;
    GLenum err = glewInit();
    if(err != GLEW_OK) {
      printf("Glew initialization error: %d\n", err);
    }
    _bInitializedGlew = true;
  }

And this is how I compile the shaders:

unsigned int CShader::CompileShader(const char* str, int type, bool &bSuccess)
{
    // create a new shader
    GLuint iShader = glCreateShader(type);
    const GLchar* aSourceVertex[] = { str };
    glShaderSource(iShader, 1, aSourceVertex, NULL);
    glCompileShader(iShader);

    // check if compiling went okay
    GLint bShaderCompiled = GL_FALSE;
    glGetShaderiv(iShader, GL_COMPILE_STATUS, &bShaderCompiled);
    if(bShaderCompiled != GL_TRUE) {
        // it did not.
        printf("Error compiling %sshader:\n", (type == GL_VERTEX_SHADER ? "vertex " : ""));
        int iLogLength = 0;
        int iMaxLength = 0;
        glGetShaderiv(iShader, GL_INFO_LOG_LENGTH, &iMaxLength);
        char* buffer = new char[iMaxLength];
        glGetShaderInfoLog(iShader, iMaxLength, &iLogLength, buffer);
        if(iLogLength > 0) {
            printf("%s\n", buffer);
        }
        delete[] buffer;

        // report it back
        bSuccess = false;
        // and delete the shader
        glDeleteShader(iShader);
    } else {
        // it worked!
        bSuccess = true;
    }

    // return shader
    return iShader;
}

I looked around for answers before and couldn't find a conclusive Stackoverflow answer that could help me, though it did point me in the right direction with SDL_GL_SetAttribute for setting the GL version and core profile. So in above code, I set it to 3.1 Core, which, according to Wikipedia, is #version 140, but even if I use that, I get the same error:

Error compiling vertex shader:
ERROR: 0:1: '' :  version '140' is not supported

Error compiling shader:
ERROR: 0:1: '' :  version '140' is not supported

Edit: I changed the version in attributes to 3.2 Core + Forward Compat, and now using #version 150 I get the same issue, saying 150 is not supported.

When I print the result of glGetString(GL_SHADING_LANGUAGE_VERSION) I get 1.20.

Even if I explicitly create the context after creating the SDL window, it still reports 1.20:

win_pWindow = SDL_CreateWindow(strTitle, iX, iY, width, height, SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN | ulFlags);
win_pContext = SDL_GL_CreateContext(win_pWindow);
printf("GLSL version: %s\n", glGetString(GL_SHADING_LANGUAGE_VERSION));

Answer 1

Hmm, how about that error message:

Error compiling vertex shader:
ERROR: 0:1: '' :  version '130' is not supported

That's exactly what your problem is. GLSL version 1.30 relates to OpenGL-3.0; since there were not core/compatibility profiles in that version, yet, MacOS X doesn't support it.

When it comes to modern OpenGL MacOS X only supports core profile. So you need a core profile context and have to write your shaders with a core profile version. OpenGL-3 core profiles have been introduced only with OpenGL-3.2, the corresponding GLSL version is 1.50. So you have to write #version 150 there.

Answer 2

You are not creating the context version you think you are creating:

SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE | SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG)

is just invalid, the SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG does not belong into the SDL_GL_CONTEXT_PROFILE_MASK flags, but into the SDL_GL_CONTEXT_FLAGS.

Actually, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG has the same value as SDL_GL_CONTEXT_PROFILE_COMPATIBILITY, so you did request both a core and compatibility profile at the same time. I suspect that you got a legacy context with that, which is limited to GL <=2.1 on OSX.

Answer 3

• I have heard that using SDL_Renderer bumps down the OpenGL version to a compatibility profile/a version of OpenGL that doesn't use core profile (so, a OpenGL version less than 3.2)

• Make sure you make both the window and context after setting the version etc with SDL_GLSetAttribute. So your code should look like:

  SDL_GLSetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
  SDL_GLSetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
  SDL_GLSetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
  
  //create window
  
  //create context
  

This is how I managed to get a 3.3 context on my mac. From your code, I can't see if you created both the context and window after the attributes.