/* compile with : valac --pkg gtkgl-3.0 .... */

using Gtk;
using GL;


void on_glarea_realize_event (Widget widget)
{
	print ("GTK+ version : %d.%d.%d\n", MAJOR_VERSION,
					    MINOR_VERSION,
					    MICRO_VERSION);

	var glarea = widget as GLArea;
	if (glarea.make_current () == true)
	{
		glViewport (0,0,
			    glarea.get_allocated_width (),
			    glarea.get_allocated_height ());

		glMatrixMode (GL_PROJECTION);
		glLoadIdentity ();
		glOrtho (0,100, 100,0, -1,1);
		glMatrixMode (GL_MODELVIEW);
	}
}

bool on_glarea_draw_event (Widget widget, Cairo.Context cr)
{
	var glarea = widget as GLArea;
	if (glarea.make_current () == true)
	{
		glViewport (0,0,
			    glarea.get_allocated_width (),
			    glarea.get_allocated_height ());

		 // Draw simple triangle
		glClearColor (0,0,0,1);
		glClear (GL_COLOR_BUFFER_BIT);
		glColor3f (1,1,1);
		glBegin (GL_TRIANGLES);
		glVertex2f (10,10);
		glVertex2f (10,90);
		glVertex2f (90,90);
		glEnd ();

		 // Swap backbuffer to front
		glarea.swap_buffers ();
	}

	return true;
}


int main (string[] args)
{
	int[] attrlist = { };
	attrlist += Gdk.GLConfigAttrib.RGBA;
	attrlist += Gdk.GLConfigAttrib.RED_SIZE;
	attrlist += 1;
	attrlist += Gdk.GLConfigAttrib.GREEN_SIZE;
	attrlist += 1;
	attrlist += Gdk.GLConfigAttrib.BLUE_SIZE;
	attrlist += 1;
	attrlist += Gdk.GLConfigAttrib.DOUBLEBUFFER;
	attrlist += 1;
	attrlist += Gdk.GLConfigAttrib.NONE;

	Gtk.init (ref args);

	 // test if OpenGL is available
	if (Gdk.gl_query () == false)
	{
		print ("OpenGL not supported \n");
		return -1;
	}

	var window = new Window (WindowType.TOPLEVEL);
	window.title = "Simple";
	window.destroy.connect (Gtk.main_quit);

	var box = new Box (Orientation.VERTICAL, 0);

	var glarea = new GLArea (attrlist);
	glarea.set_size_request (100, 100);
	glarea.realize.connect (on_glarea_realize_event);
	glarea.draw.connect (on_glarea_draw_event);

	var button = new Button.with_label ("Quit");
	button.clicked.connect (Gtk.main_quit);

	box.pack_start (glarea, true, true);
	box.pack_start (button, false, false);
	window.add (box);
	window.show_all ();

	Gtk.main ();

	return 0;
}