glfw/lib/glext.c

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//========================================================================
// GLFW - An OpenGL framework
// Platform: Any
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// API version: 3.0
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// WWW: http://www.glfw.org/
//------------------------------------------------------------------------
// Copyright (c) 2002-2006 Marcus Geelnard
// Copyright (c) 2006-2010 Camilla Berglund <elmindreda@elmindreda.org>
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would
// be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
// be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
// distribution.
//
//========================================================================
#include "internal.h"
//************************************************************************
//**** GLFW internal functions ****
//************************************************************************
#ifndef GL_VERSION_3_0
#define GL_NUM_EXTENSIONS 0x821D
#endif
//========================================================================
// Parses the OpenGL version string and extracts the version number
//========================================================================
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void _glfwParseGLVersion(int* major, int* minor, int* rev)
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{
GLuint _major, _minor = 0, _rev = 0;
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const GLubyte* version;
const GLubyte* ptr;
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// Get OpenGL version string
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version = glGetString(GL_VERSION);
if (!version)
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return;
// Parse string
ptr = version;
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for (_major = 0; *ptr >= '0' && *ptr <= '9'; ptr++)
_major = 10 * _major + (*ptr - '0');
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if (*ptr == '.')
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{
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ptr++;
for (_minor = 0; *ptr >= '0' && *ptr <= '9'; ptr++)
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_minor = 10*_minor + (*ptr - '0');
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if (*ptr == '.')
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{
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ptr++;
for (_rev = 0; *ptr >= '0' && *ptr <= '9'; ptr++)
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_rev = 10*_rev + (*ptr - '0');
}
}
// Return parsed values
*major = _major;
*minor = _minor;
*rev = _rev;
}
//========================================================================
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// Check if a string can be found in an OpenGL extension string
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//========================================================================
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int _glfwStringInExtensionString(const char* string,
const GLubyte* extensions)
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{
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const GLubyte* start;
GLubyte* where;
GLubyte* terminator;
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// It takes a bit of care to be fool-proof about parsing the
// OpenGL extensions string. Don't be fooled by sub-strings,
// etc.
start = extensions;
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for (;;)
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{
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where = (GLubyte*) strstr((const char*) start, string);
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if (!where)
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return GL_FALSE;
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terminator = where + strlen(string);
if (where == start || *(where - 1) == ' ')
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{
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if (*terminator == ' ' || *terminator == '\0')
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break;
}
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start = terminator;
}
return GL_TRUE;
}
//************************************************************************
//**** GLFW user functions ****
//************************************************************************
//========================================================================
// Check if an OpenGL extension is available at runtime
//========================================================================
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GLFWAPI int glfwExtensionSupported(const char* extension)
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{
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const GLubyte* extensions;
GLubyte* where;
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GLint count;
int i;
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if (!_glfwInitialized || !_glfwWin.opened)
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return GL_FALSE;
// Extension names should not have spaces
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where = (GLubyte*) strchr(extension, ' ');
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if (where || *extension == '\0')
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return GL_FALSE;
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if (_glfwWin.glMajor < 3)
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{
// Check if extension is in the old style OpenGL extensions string
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extensions = glGetString(GL_EXTENSIONS);
if (extensions != NULL)
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{
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if (_glfwStringInExtensionString(extension, extensions))
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return GL_TRUE;
}
}
else
{
// Check if extension is in the modern OpenGL extensions string list
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glGetIntegerv(GL_NUM_EXTENSIONS, &count);
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for (i = 0; i < count; i++)
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{
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if (strcmp((const char*) _glfwWin.GetStringi(GL_EXTENSIONS, i),
extension) == 0)
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{
return GL_TRUE;
}
}
}
// Additional platform specific extension checking (e.g. WGL)
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if (_glfwPlatformExtensionSupported(extension))
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return GL_TRUE;
return GL_FALSE;
}
//========================================================================
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// Get the function pointer to an OpenGL function.
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// This function can be used to get access to extended OpenGL functions.
//========================================================================
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GLFWAPI void* glfwGetProcAddress(const char* procname)
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{
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if (!_glfwInitialized || !_glfwWin.opened)
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return NULL;
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return _glfwPlatformGetProcAddress(procname);
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}
//========================================================================
// Returns the OpenGL version
//========================================================================
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GLFWAPI void glfwGetGLVersion(int* major, int* minor, int* rev)
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{
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if (!_glfwInitialized || !_glfwWin.opened)
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return;
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if (major != NULL)
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*major = _glfwWin.glMajor;
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if (minor != NULL)
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*minor = _glfwWin.glMinor;
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if (rev != NULL)
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*rev = _glfwWin.glRevision;
}