itgmania212121/stepmania/src/RageDisplay_OGL_Extensions.cpp

#include "global.h"

#if defined(WIN32)
#include <windows.h>
#endif

#if !defined(DARWIN)
# include <GL/gl.h>
# include <GL/glu.h>
#else
# include <OpenGL/gl.h>
# include <OpenGL/glu.h>
#endif

#undef __glext_h_
#include "glext.h"

#include "RageDisplay_OGL_Extensions.h"
#include "arch/LowLevelWindow/LowLevelWindow.h"

GLExt_t GLExt;

bool HasExtension( CString ext );

#define F(n)  { (void **) &GLExt.n , #n }

struct func_t
{
	void **p;
	const char *name;
};

static bool LoadAllOrNothing( struct func_t *funcs, LowLevelWindow *pWind )
{
	bool bGotAll = true;
	for( unsigned i = 0; funcs[i].p != NULL; ++i )
	{
		*funcs[i].p = pWind->GetProcAddress( funcs[i].name );
		if( *funcs[i].p == NULL )
		{
			bGotAll = false;
			break;
		}
	}

	if( bGotAll )
		return true;

	/* If any function in the array wasn't found, clear them all. */
	for( unsigned i = 0; funcs[i].p != NULL; ++i )
		*funcs[i].p = NULL;

	return false;
}

void GLExt_t::Load( LowLevelWindow *pWind )
{
	memset( this, 0, sizeof(*this) );

	m_bEXT_texture_env_combine = HasExtension("GL_EXT_texture_env_combine");
	m_bGL_EXT_bgra = HasExtension("GL_EXT_bgra");

#if defined(WIN32)
	if( HasExtension("WGL_EXT_swap_control") )
		wglSwapIntervalEXT = (PWSWAPINTERVALEXTPROC) pWind->GetProcAddress("wglSwapIntervalEXT");
#elif defined(DARWIN)
	wglSwapIntervalEXT = wglSwapIntervalEXT;
#endif

	if( HasExtension("GL_EXT_paletted_texture") )
	{
		glColorTableEXT = (PFNGLCOLORTABLEPROC) pWind->GetProcAddress("glColorTableEXT");
		glGetColorTableParameterivEXT = (PFNGLCOLORTABLEPARAMETERIVPROC) pWind->GetProcAddress("glGetColorTableParameterivEXT");
	}

	if( HasExtension("GL_ARB_multitexture") )
		glActiveTextureARB = (PFNGLACTIVETEXTUREARBPROC) pWind->GetProcAddress("glActiveTextureARB");

	/*
	 * Find extension functions.
	 *
	 * X11R6.7.0 (or possibly ATI's drivers) seem to be returning bogus values for glBindBufferARB
	 * if we don't actually check for GL_ARB_vertex_buffer_object. 
	 * https://sf.net/tracker/download.php?group_id=37892&atid=421366&file_id=88086&aid=958820
	 * https://sf.net/tracker/download.php?group_id=37892&atid=421366&file_id=85542&aid=944836
	 *
	 * Let's check them all, to be safe.
	 */
	if( HasExtension("GL_ARB_vertex_buffer_object") )
	{
		func_t funcs[] = {
			F( glGenBuffersARB ),
			F( glBindBufferARB ),
			F( glBufferDataARB ),
			F( glBufferSubDataARB ),
			F( glDeleteBuffersARB ),
			{ NULL, NULL },
		};

		LoadAllOrNothing( funcs, pWind );
	}

	if( HasExtension("GL_EXT_draw_range_elements") )
		GLExt.glDrawRangeElements = (PFNGLDRAWRANGEELEMENTSPROC) pWind->GetProcAddress("glDrawRangeElements");
}