glfw/lib/glext.c
2010-09-08 17:01:39 +02:00

211 lines
6.1 KiB
C

//========================================================================
// GLFW - An OpenGL framework
// Platform: Any
// API version: 3.0
// 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"
#include <string.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');
if (*ptr == '.')
{
ptr++;
for (_minor = 0; *ptr >= '0' && *ptr <= '9'; ptr++)
_minor = 10*_minor + (*ptr - '0');
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;
}
//========================================================================
// Check if a string can be found in an OpenGL extension string
//========================================================================
int _glfwStringInExtensionString(const char* string,
const GLubyte* extensions)
{
const GLubyte* start;
GLubyte* where;
GLubyte* 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;
for (;;)
{
where = (GLubyte*) strstr((const char*) start, string);
if (!where)
return GL_FALSE;
terminator = where + strlen(string);
if (where == start || *(where - 1) == ' ')
{
if (*terminator == ' ' || *terminator == '\0')
break;
}
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;
}
//========================================================================
// Get the function pointer to an OpenGL function.
// 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;
if (minor != NULL)
*minor = _glfwWin.glMinor;
if (rev != NULL)
*rev = _glfwWin.glRevision;
}