gl.cc

/*===========================================================================*\
 *                                                                           *
 *                              OpenFlipper                                  *
 *           Copyright (c) 2001-2015, RWTH-Aachen University                 *
 *           Department of Computer Graphics and Multimedia                  *
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 *                            www.openflipper.org                            *
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 * This file is part of OpenFlipper.                                         *
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\*===========================================================================*/

#include <ACG/GL/acg_glew.hh>
#include "gl.hh"

#include <cstdlib>
#include <sstream>
#include <iostream>



//=============================================================================
namespace ACG {
//=============================================================================
namespace {
inline const char *_getExtensionString() {

  // glGetString(GL_EXTENSIONS) is deprecated and not available in core profile
    if(!openGLVersion(3,0))
    {
        return (const char*) glGetString(GL_EXTENSIONS);
    }

  // enumerate extensions with glGetStringi(GL_EXTENSIONS, id) instead
#ifndef __APPLE__
  if (!glGetStringi)
    glewInit();
#endif
  static std::string supported_str;

  if (supported_str.empty()) {
    GLint extensions = 0;
    glGetIntegerv(GL_NUM_EXTENSIONS, &extensions);

    for (int i = 0; i < extensions; ++i) {

      const char *supported_cstr = reinterpret_cast<const char*>(glGetStringi(GL_EXTENSIONS, i));
    
      if (supported_cstr == 0) {
        std::cerr << "\x1b[1;31mACG::checkExtensionsSupported: "
          "glGetStringi(GL_EXTENSIONS, "<<i<<") call failed.\x1b[0m\n";
        return "";
      }

      supported_str += supported_cstr;
      if (i + 1 < extensions)
        supported_str += " ";
    }
  }

  return supported_str.c_str();
}
}

std::string getExtensionString()
{
    return _getExtensionString();
}

bool checkExtensionSupported( const std::string& _extension )  {
    static const std::string supported_str(_getExtensionString());

    /*
     * supported_str is a space delimited list. Tokenize it. Simply searching
     * for _extension within supported_str yields false positives if the
     * requested extension is a substring of a supported one.
     */
    for (std::istringstream supported(supported_str); !supported.eof(); ) {
        std::string feature;
        supported >> feature;
        if (feature == _extension) return true;
    }
    return false;
}

bool openGLVersion( const int _major, const int _minor, bool _verbose  )  {

  // Read OpenGL Version string
  std::string glVersionString = (const char*)glGetString(GL_VERSION);

  // Use string stream to parse
  std::istringstream stream;
  stream.str(glVersionString);

  // Buffer for the dot between major and minor
  char dot;

  // Read Major version number
  int major ;
  stream >> major;
  stream >> dot;

  // Read minor version number
  int minor;
  stream >> minor;

  if ( (_major > major) || ( (_major == major) && (_minor > minor))  ) {
    if(_verbose)
    {
      std::cerr << "OpenGL Version check failed. Required  : " << _major << "." << _minor << std::endl;
      std::cerr << "OpenGL Version check failed. Available : " << major << "." << minor << std::endl;
    }
    return false;
  }

  return true;
}

static bool compatibilityProfile_ = false;

void compatibilityProfile( bool _enableCoreProfile ) {
  compatibilityProfile_ = _enableCoreProfile;
}

bool compatibilityProfile( ) {
  return compatibilityProfile_;
}

//=============================================================================
}  // namespace ACG
//=============================================================================