/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  Sam Lantinga

    This library is free software; you can redistribute it and/or

    modify it under the terms of the GNU Library General Public

    License as published by the Free Software Foundation; either

    version 2 of the License, or (at your option) any later version.

    This library 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

    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public

    License along with this library; if not, write to the Free

    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga

    slouken@libsdl.org

*/

#ifdef SAVE_RCSID

static char rcsid =

 "@(#) $Id$";

#endif

#include <stdlib.h>	/* For getenv() prototype */

#include <string.h>

#include "SDL_events_c.h"

#include "SDL_error.h"

#include "SDL_x11video.h"

#include "SDL_x11dga_c.h"

#include "SDL_x11gl_c.h"

#define DEFAULT_OPENGL	"libGL.so.1"

/* return the preferred visual to use for openGL graphics */

XVisualInfo *X11_GL_GetVisual(_THIS)

{

#ifdef HAVE_OPENGL

	/* 64 seems nice. */

	int attribs[64];

	int i;

	/* load the gl driver from a default path */

	if ( ! this->gl_config.driver_loaded ) {

	        /* no driver has been loaded, use default (ourselves) */

	        if ( X11_GL_LoadLibrary(this, NULL) < 0 ) {

		        return NULL;

		}

	}

	/* See if we already have a window which we must use */

	if ( SDL_windowid ) {

		XWindowAttributes a;

		XVisualInfo vi_in;

		int out_count;

		XGetWindowAttributes(SDL_Display, SDL_Window, &a);

		vi_in.screen = SDL_Screen;

		vi_in.visualid = XVisualIDFromVisual(a.visual);

		glx_visualinfo = XGetVisualInfo(SDL_Display,

	                     VisualScreenMask|VisualIDMask, &vi_in, &out_count);

		return glx_visualinfo;

	}

        /* Setup our GLX attributes according to the gl_config. */

	i = 0;

	attribs[i++] = GLX_RGBA;

	attribs[i++] = GLX_RED_SIZE;

	attribs[i++] = this->gl_config.red_size;

	attribs[i++] = GLX_GREEN_SIZE;

	attribs[i++] = this->gl_config.green_size;

	attribs[i++] = GLX_BLUE_SIZE;

	attribs[i++] = this->gl_config.blue_size;

	if( this->gl_config.alpha_size ) {

		attribs[i++] = GLX_ALPHA_SIZE;

		attribs[i++] = this->gl_config.alpha_size;

	}

	if( this->gl_config.buffer_size ) {

		attribs[i++] = GLX_BUFFER_SIZE;

		attribs[i++] = this->gl_config.buffer_size;

	}

	if( this->gl_config.double_buffer ) {

		attribs[i++] = GLX_DOUBLEBUFFER;

	}

	attribs[i++] = GLX_DEPTH_SIZE;

	attribs[i++] = this->gl_config.depth_size;

	if( this->gl_config.stencil_size ) {

		attribs[i++] = GLX_STENCIL_SIZE;

		attribs[i++] = this->gl_config.stencil_size;

	}

	if( this->gl_config.accum_red_size ) {

		attribs[i++] = GLX_ACCUM_RED_SIZE;

		attribs[i++] = this->gl_config.accum_red_size;

	}

	if( this->gl_config.accum_green_size ) {

		attribs[i++] = GLX_ACCUM_GREEN_SIZE;

		attribs[i++] = this->gl_config.accum_green_size;

	}

	if( this->gl_config.accum_blue_size ) {

		attribs[i++] = GLX_ACCUM_BLUE_SIZE;

		attribs[i++] = this->gl_config.accum_blue_size;

	}

	if( this->gl_config.accum_alpha_size ) {

		attribs[i++] = GLX_ACCUM_ALPHA_SIZE;

		attribs[i++] = this->gl_config.accum_alpha_size;

	}

	if( this->gl_config.stereo ) {

		attribs[i++] = GLX_STEREO;

		attribs[i++] = this->gl_config.stereo;

	}

	if( this->gl_config.multisamplebuffers ) {

		attribs[i++] = GLX_SAMPLE_BUFFERS_ARB;

		attribs[i++] = this->gl_config.multisamplebuffers;

	}

	if( this->gl_config.multisamplesamples ) {

		attribs[i++] = GLX_SAMPLES_ARB;

		attribs[i++] = this->gl_config.multisamplesamples;

	}

#ifdef GLX_DIRECT_COLOR /* Try for a DirectColor visual for gamma support */

	attribs[i++] = GLX_X_VISUAL_TYPE;

	attribs[i++] = GLX_DIRECT_COLOR;

#endif

	attribs[i++] = None;

 	glx_visualinfo = this->gl_data->glXChooseVisual(GFX_Display, 

						  SDL_Screen, attribs);

#ifdef GLX_DIRECT_COLOR

	if( !glx_visualinfo ) { /* No DirectColor visual?  Try again.. */

		attribs[i-3] = None;

 		glx_visualinfo = this->gl_data->glXChooseVisual(GFX_Display, 

						  SDL_Screen, attribs);

	}

#endif

	if( !glx_visualinfo ) {

		SDL_SetError( "Couldn't find matching GLX visual");

		return NULL;

	}

	return glx_visualinfo;

#else

	SDL_SetError("X11 driver not configured with OpenGL");

	return NULL;

#endif

}

int X11_GL_CreateWindow(_THIS, int w, int h)

{

	int retval;

#ifdef HAVE_OPENGL

	XSetWindowAttributes attributes;

	unsigned long mask;

	unsigned long black;

	black = (glx_visualinfo->visual == DefaultVisual(SDL_Display,

						 	SDL_Screen))

	       	? BlackPixel(SDL_Display, SDL_Screen) : 0;

	attributes.background_pixel = black;

	attributes.border_pixel = black;

	attributes.colormap = SDL_XColorMap;

	mask = CWBackPixel | CWBorderPixel | CWColormap;

	SDL_Window = XCreateWindow(SDL_Display, WMwindow,

			0, 0, w, h, 0, glx_visualinfo->depth,

			InputOutput, glx_visualinfo->visual,

			mask, &attributes);

	if ( !SDL_Window ) {

		SDL_SetError("Could not create window");

		return -1;

	}

	retval = 0;

#else

	SDL_SetError("X11 driver not configured with OpenGL");

	retval = -1;

#endif

	return(retval);

}

int X11_GL_CreateContext(_THIS)

{

	int retval;

#ifdef HAVE_OPENGL

	/* We do this to create a clean separation between X and GLX errors. */

	XSync( SDL_Display, False );

	glx_context = this->gl_data->glXCreateContext(GFX_Display, 

				     glx_visualinfo, NULL, True);

	XSync( GFX_Display, False );

	if (glx_context == NULL) {

		SDL_SetError("Could not create GL context");

		return -1;

	}

	gl_active = 1;

#else

	SDL_SetError("X11 driver not configured with OpenGL");

#endif

	if ( gl_active ) {

		retval = 0;

	} else {

		retval = -1;

	}

	return(retval);

}

void X11_GL_Shutdown(_THIS)

{

#ifdef HAVE_OPENGL

	/* Clean up OpenGL */

	if( glx_context ) {

		this->gl_data->glXMakeCurrent(GFX_Display, None, NULL);

		if (glx_context != NULL)

			this->gl_data->glXDestroyContext(GFX_Display, glx_context);

		if( this->gl_data->glXReleaseBuffersMESA ) {

		    this->gl_data->glXReleaseBuffersMESA(GFX_Display,SDL_Window);

		}

		glx_context = NULL;

	}

	gl_active = 0;

#endif /* HAVE_OPENGL */

}

#ifdef HAVE_OPENGL

static int ExtensionSupported(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 = current_video->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 1;

		start = terminator;

	}

	return 0;

}

/* Make the current context active */

int X11_GL_MakeCurrent(_THIS)

{

	int retval;

	retval = 0;

	if ( ! this->gl_data->glXMakeCurrent(GFX_Display,

	                                     SDL_Window, glx_context) ) {

		SDL_SetError("Unable to make GL context current");

		retval = -1;

	}

	XSync( GFX_Display, False );

	/* 

	 * The context is now current, check for glXReleaseBuffersMESA() 

	 * extension. If extension is _not_ supported, destroy the pointer 

	 * (to make sure it will not be called in X11_GL_Shutdown() ).

	 * 

	 * DRI/Mesa drivers include glXReleaseBuffersMESA() in the libGL.so, 

	 * but there's no need to call it (is is only needed for some old 

	 * non-DRI drivers).

	 * 

	 * When using for example glew (http://glew.sf.net), dlsym() for

	 * glXReleaseBuffersMESA() returns the pointer from the glew library

	 * (namespace conflict).

	 *

	 * The glXReleaseBuffersMESA() pointer in the glew is NULL, if the 

	 * driver doesn't support this extension. So blindly calling it will

	 * cause segfault with DRI/Mesa drivers!

	 * 

	 */

	if ( ! ExtensionSupported("glXReleaseBuffersMESA") ) {

		this->gl_data->glXReleaseBuffersMESA = NULL;

	}

	/* More Voodoo X server workarounds... Grr... */

	SDL_Lock_EventThread();

	X11_CheckDGAMouse(this);

	SDL_Unlock_EventThread();

	return(retval);

}

/* Get attribute data from glX. */

int X11_GL_GetAttribute(_THIS, SDL_GLattr attrib, int* value)

{

	int retval;

	int glx_attrib = None;

	switch( attrib ) {

	    case SDL_GL_RED_SIZE:

		glx_attrib = GLX_RED_SIZE;

		break;

	    case SDL_GL_GREEN_SIZE:

		glx_attrib = GLX_GREEN_SIZE;

		break;

	    case SDL_GL_BLUE_SIZE:

		glx_attrib = GLX_BLUE_SIZE;

		break;

	    case SDL_GL_ALPHA_SIZE:

		glx_attrib = GLX_ALPHA_SIZE;

		break;

	    case SDL_GL_DOUBLEBUFFER:

		glx_attrib = GLX_DOUBLEBUFFER;

		break;

	    case SDL_GL_BUFFER_SIZE:

		glx_attrib = GLX_BUFFER_SIZE;

		break;

	    case SDL_GL_DEPTH_SIZE:

		glx_attrib = GLX_DEPTH_SIZE;

		break;

	    case SDL_GL_STENCIL_SIZE:

		glx_attrib = GLX_STENCIL_SIZE;

		break;

	    case SDL_GL_ACCUM_RED_SIZE:

		glx_attrib = GLX_ACCUM_RED_SIZE;

		break;

	    case SDL_GL_ACCUM_GREEN_SIZE:

		glx_attrib = GLX_ACCUM_GREEN_SIZE;

		break;

	    case SDL_GL_ACCUM_BLUE_SIZE:

		glx_attrib = GLX_ACCUM_BLUE_SIZE;

		break;

	    case SDL_GL_ACCUM_ALPHA_SIZE:

		glx_attrib = GLX_ACCUM_ALPHA_SIZE;

		break;

	    case SDL_GL_STEREO:

		glx_attrib = GLX_STEREO;

		break;

 	    case SDL_GL_MULTISAMPLEBUFFERS:

 		glx_attrib = GLX_SAMPLE_BUFFERS_ARB;

 		break;

 	    case SDL_GL_MULTISAMPLESAMPLES:

 		glx_attrib = GLX_SAMPLES_ARB;

 		break;

	    default:

		return(-1);

	}

	retval = this->gl_data->glXGetConfig(GFX_Display, glx_visualinfo, glx_attrib, value);

	return retval;

}

void X11_GL_SwapBuffers(_THIS)

{

	this->gl_data->glXSwapBuffers(GFX_Display, SDL_Window);

}

#endif /* HAVE_OPENGL */

void X11_GL_UnloadLibrary(_THIS)

{

#ifdef HAVE_OPENGL

	if ( this->gl_config.driver_loaded ) {

		dlclose(this->gl_config.dll_handle);

		this->gl_data->glXGetProcAddress = NULL;

		this->gl_data->glXChooseVisual = NULL;

		this->gl_data->glXCreateContext = NULL;

		this->gl_data->glXDestroyContext = NULL;

		this->gl_data->glXMakeCurrent = NULL;

		this->gl_data->glXSwapBuffers = NULL;

		this->gl_config.dll_handle = NULL;

		this->gl_config.driver_loaded = 0;

	}

#endif

}

#ifdef HAVE_OPENGL

/* Passing a NULL path means load pointers from the application */

int X11_GL_LoadLibrary(_THIS, const char* path) 

{

	void* handle;

	int dlopen_flags;

 	if ( gl_active ) {

 		SDL_SetError("OpenGL context already created");

 		return -1;

 	}

#ifdef RTLD_GLOBAL

	dlopen_flags = RTLD_LAZY | RTLD_GLOBAL;

#else

	dlopen_flags = RTLD_LAZY;

#endif

	handle = dlopen(path, dlopen_flags);

	/* Catch the case where the application isn't linked with GL */

	if ( (dlsym(handle, "glXChooseVisual") == NULL) && (path == NULL) ) {

		dlclose(handle);

		path = getenv("SDL_VIDEO_GL_DRIVER");

		if ( path == NULL ) {

			path = DEFAULT_OPENGL;

		}

		handle = dlopen(path, dlopen_flags);

	}

	if ( handle == NULL ) {

		SDL_SetError("Could not load OpenGL library");

		return -1;

	}

	/* Unload the old driver and reset the pointers */

	X11_GL_UnloadLibrary(this);

	/* Load new function pointers */

	this->gl_data->glXGetProcAddress =

		(void *(*)(const GLubyte *)) dlsym(handle, "glXGetProcAddressARB");

	this->gl_data->glXChooseVisual =

		(XVisualInfo *(*)(Display *, int, int *)) dlsym(handle, "glXChooseVisual");

	this->gl_data->glXCreateContext =

		(GLXContext (*)(Display *, XVisualInfo *, GLXContext, int)) dlsym(handle, "glXCreateContext");

	this->gl_data->glXDestroyContext =

		(void (*)(Display *, GLXContext)) dlsym(handle, "glXDestroyContext");

	this->gl_data->glXMakeCurrent =

		(int (*)(Display *, GLXDrawable, GLXContext)) dlsym(handle, "glXMakeCurrent");

	this->gl_data->glXSwapBuffers =

		(void (*)(Display *, GLXDrawable)) dlsym(handle, "glXSwapBuffers");

	this->gl_data->glXGetConfig =

		(int (*)(Display *, XVisualInfo *, int, int *)) dlsym(handle, "glXGetConfig");

	this->gl_data->glXQueryExtensionsString =

		(const char *(*)(Display *, int)) dlsym(handle, "glXQueryExtensionsString");

	/* We don't compare below for this in case we're not using Mesa. */

	this->gl_data->glXReleaseBuffersMESA =

		(void (*)(Display *, GLXDrawable)) dlsym( handle, "glXReleaseBuffersMESA" );

	if ( (this->gl_data->glXChooseVisual == NULL) || 

	     (this->gl_data->glXCreateContext == NULL) ||

	     (this->gl_data->glXDestroyContext == NULL) ||

	     (this->gl_data->glXMakeCurrent == NULL) ||

	     (this->gl_data->glXSwapBuffers == NULL) ||

	     (this->gl_data->glXGetConfig == NULL) ||

	     (this->gl_data->glXQueryExtensionsString == NULL)) {

		SDL_SetError("Could not retrieve OpenGL functions");

		return -1;

	}

	this->gl_config.dll_handle = handle;

	this->gl_config.driver_loaded = 1;

	if ( path ) {

		strncpy(this->gl_config.driver_path, path,

			sizeof(this->gl_config.driver_path)-1);

	} else {

		strcpy(this->gl_config.driver_path, "");

	}

	return 0;

}

void *X11_GL_GetProcAddress(_THIS, const char* proc)

{

	static char procname[1024];

	void* handle;

	void* retval;

	handle = this->gl_config.dll_handle;

	if ( this->gl_data->glXGetProcAddress ) {

		return this->gl_data->glXGetProcAddress(proc);

	}

#if defined(__OpenBSD__) && !defined(__ELF__)

#undef dlsym(x,y);

#endif

	retval = dlsym(handle, proc);

	if (!retval && strlen(proc) <= 1022) {

		procname[0] = '_';

		strcpy(procname + 1, proc);

		retval = dlsym(handle, procname);

	}

	return retval;

}

#endif /* HAVE_OPENGL */