/**

 * $Id: video_gl.c,v 1.2 2007-01-15 12:57:12 nkeynes Exp $

 *

 * Common GL code that doesn't depend on a specific implementation

 *

 * Copyright (c) 2005 Nathan Keynes.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 */

#include "dream.h"

#include "drivers/video_gl.h"

#include <GL/gl.h>

char *required_extensions[] = { "GL_EXT_framebuffer_object", NULL };

/**

 * Test if a specific extension is supported. From opengl.org

 * @param extension extension name to check for

 * @return TRUE if supported, otherwise FALSE.

 */

gboolean isGLExtensionSupported( const char *extension )

{

    const GLubyte *extensions = NULL;

    const GLubyte *start;

    GLubyte *where, *terminator;

    /* Extension names should not have spaces. */

    where = (GLubyte *) strchr(extension, ' ');

    if (where || *extension == '\0')

	return 0;

    extensions = glGetString(GL_EXTENSIONS);

    /* 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, extension);

	if (!where)

	    break;

	terminator = where + strlen(extension);

	if (where == start || *(where - 1) == ' ')

	    if (*terminator == ' ' || *terminator == '\0')

		return TRUE;

	start = terminator;

    }

    return FALSE;

}

gboolean hasRequiredGLExtensions( ) 

{

    int i;

    gboolean isOK = TRUE;

    for( i=0; required_extensions[i] != NULL; i++ ) {

	if( !isGLExtensionSupported(required_extensions[i]) ) {

	    ERROR( "Required OpenGL extension not supported: %s", required_extensions[i] );

	    isOK = FALSE;

	}

    }

    return isOK;

}