/************************************************************************
     File:        simple2.cpp

     Author:     
                  Michael L Gleicher, gleicher@cs.wisc.edu
     Modifier
                  Yu-Chi Lai, yu-chi@cs.wisc.edu
     
     Comment:     written 10/16/99, Michael L Gleicher
		              For demoing the basic operation in OpenGL
   
     Platform:    Visio Studio.Net 2003
*************************************************************************/

#include <FL/Fl_Gl_Window.h>
#include <Fl/Fl.h>
#include <windows.h>
#include <GL/gl.h>
#include <Fl/Fl_Double_Window.h>
#include <Fl/Fl_Button.h>

// make a Gl window that draws something:
class MyGlWindow : public Fl_Gl_Window {
public:
	float r,g,b;
	MyGlWindow(int x, int y, int w, int h) :
	  Fl_Gl_Window(x,y,w,h,"My GL Window")   {
		  r = g = 1;
		  b = 0;
	  }

private:
	void draw() {	// the draw method must be private
		glMatrixMode(GL_PROJECTION);	// set up coord system
		glLoadIdentity();			// reset it
		glOrtho(-1,1,-1,1,-1,1);	// set it to be -1 to 1 in each axis
		glMatrixMode(GL_MODELVIEW);	// back to normal mode
		glLoadIdentity();			// clear what anyone else did

		glClearColor(0,0,0,0);		// clear the window to black
		glClear(GL_COLOR_BUFFER_BIT);	// clear the window

		glColor3f(r,g,b);			// draw in yellow
		glRectf(-.5,-.5,.5,.5);		// draw a filled rectangle
	};
};

//********************************************************************************
//
// * A simple callback to do something
//================================================================================
void changeColor(Fl_Widget* /*button*/, MyGlWindow* myWind)
//================================================================================
{
	myWind->r = 1 - myWind->r;
	myWind->g = 1 - myWind->g;
	myWind->b = 1 - myWind->b;
	myWind->damage(1);
}

// the main routine makes the window, and then runs an even loop
// until the window is closed
main()
{
	Fl_Double_Window* wind = new Fl_Double_Window(100,100,400,300,"GL Sample");

	wind->begin();		// put widgets inside of the window
		MyGlWindow* gl = new MyGlWindow(10,10,280,280);
		Fl_Button* bt = new Fl_Button(300,10,70,25,"Color");
		bt->callback((Fl_Callback*) changeColor, gl);
	wind->end();

	wind->show();	// this actually opens the window

	Fl::run();
	delete gl;

	return 1;
}