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
//========================================================================
void _glfwParseGLVersion( int *major, int *minor, int *rev )
{
GLuint _major, _minor = 0, _rev = 0;
const GLubyte *version;
const GLubyte *ptr;
// Get OpenGL version string
version = glGetString( GL_VERSION );
if( !version )
return;
// Parse string
ptr = version;
for( _major = 0; *ptr >= '0' && *ptr <= '9'; ptr ++ )
_major = 10*_major + (*ptr - '0');
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if( *ptr == '.' )
{
ptr ++;
for( _minor = 0; *ptr >= '0' && *ptr <= '9'; ptr ++ )
_minor = 10*_minor + (*ptr - '0');
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if( *ptr == '.' )
{
ptr ++;
for( _rev = 0; *ptr >= '0' && *ptr <= '9'; ptr ++ )
_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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//========================================================================
int _glfwStringInExtensionString( const char *string,
const GLubyte *extensions )
{
const GLubyte *start;
GLubyte *where, *terminator;
// 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;
while( 1 )
{
where = (GLubyte *) strstr( (const char *) start, string );
if( !where )
return GL_FALSE;
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terminator = where + strlen( string );
if( where == start || *(where - 1) == ' ' )
{
if( *terminator == ' ' || *terminator == '\0' )
break;
}
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start = terminator;
}
return GL_TRUE;
}
//************************************************************************
//**** GLFW user functions ****
//************************************************************************
//========================================================================
// Check if an OpenGL extension is available at runtime
//========================================================================
GLFWAPI int glfwExtensionSupported( const char *extension )
{
const GLubyte *extensions;
GLubyte *where;
GLint count;
int i;
if( !_glfwInitialized || !_glfwWin.opened )
return GL_FALSE;
// Extension names should not have spaces
where = (GLubyte *) strchr( extension, ' ' );
if( where || *extension == '\0' )
return GL_FALSE;
if( _glfwWin.glMajor < 3 )
{
// Check if extension is in the old style OpenGL extensions string
extensions = glGetString( GL_EXTENSIONS );
if( extensions != NULL )
{
if( _glfwStringInExtensionString( extension, extensions ) )
return GL_TRUE;
}
}
else
{
// Check if extension is in the modern OpenGL extensions string list
glGetIntegerv( GL_NUM_EXTENSIONS, &count );
for( i = 0; i < count; i++ )
{
if( strcmp( (const char*) _glfwWin.GetStringi( GL_EXTENSIONS, i ),
extension ) == 0 )
{
return GL_TRUE;
}
}
}
// Additional platform specific extension checking (e.g. WGL)
if( _glfwPlatformExtensionSupported( extension ) )
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.
//========================================================================
GLFWAPI void * glfwGetProcAddress( const char *procname )
{
if( !_glfwInitialized || !_glfwWin.opened )
return NULL;
return _glfwPlatformGetProcAddress( procname );
}
//========================================================================
// Returns the OpenGL version
//========================================================================
GLFWAPI void glfwGetGLVersion( int *major, int *minor, int *rev )
{
if( !_glfwInitialized || !_glfwWin.opened )
return;
if( major != NULL )
*major = _glfwWin.glMajor;
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if( minor != NULL )
*minor = _glfwWin.glMinor;
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if( rev != NULL )
*rev = _glfwWin.glRevision;
}