// example file for fltk-gl
// author: Matteo Lucarelli
// compile with:
// g++ `fltk-config --ldflags --use-gl` gl-with-fltk.cpp -o gl-with-fltk

#include <stdlib.h>

// on some system these are not equals
#include <math.h>
//#include <FL/math.h>

// on some system these are not equals
#include <GL/gl.h>
//#include <FL/gl.h>

#include <FL/Fl.H>
#include <FL/Fl_Single_Window.H>
#include <FL/Fl_Hor_Slider.H>
#include <FL/Fl_Toggle_Light_Button.H>
#include <FL/Fl_Gl_Window.H>

#define MAX_SIDES 100
#define MIN_SIDES 3

///////////////////////////////////////////////////////////////////////////////

// this should be in a header file
class gl_frame : public Fl_Gl_Window
{
public:
	gl_frame(int x,int y,int w,int h,const char *l=0);
	int sides;
	bool grow;
protected:
	void draw();
};

gl_frame::gl_frame(int x,int y,int w,int h,const char *l) :Fl_Gl_Window(x,y,w,h,l) 
{
	sides = 3;
	grow = true;
}

void gl_frame::draw() 
{
	if (!valid()) {
		valid(1);
		glLoadIdentity();
		glViewport(0,0,w(),h());
	}
	glClear(GL_COLOR_BUFFER_BIT);
	glColor3f(.5,.6,.7);
	glBegin(GL_POLYGON);
		for (int i=0; i<sides; i++) 
			glVertex3f(cos(i*2*M_PI/sides),sin(i*2*M_PI/sides),0);
	glEnd();
}

///////////////////////////////////////////////////////////////////////////////

void timer_cb(void *p) 
{
	gl_frame *glf = (gl_frame*)p;
	
	if (glf->sides==MIN_SIDES) glf->grow=true;
	if (glf->sides==MAX_SIDES) glf->grow=false;
	
	if (glf->grow) glf->sides++;
	else glf->sides--;
	
	glf->redraw();
	
	Fl::repeat_timeout((2.0/glf->sides),timer_cb,p);
}

void double_cb(Fl_Widget *o, void *p) 
{
	gl_frame *glf = (gl_frame*)p;
	glf->mode(((Fl_Button *)o)->value() ? Fl_Mode(FL_DOUBLE|FL_RGB) : FL_RGB);
}

///////////////////////////////////////////////////////////////////////////////

int main(int argc, char **argv) 
{
	gl_frame glf(10,10,280,280);
	glf.mode(FL_RGB);

	Fl_Single_Window window(300,330); 
		window.add(glf);
		window.resizable(&glf);
		Fl_Toggle_Light_Button db(10,295,window.w()-20,30,"Double Buffered");
		db.callback(double_cb,&glf);
	window.end();
	
	window.show(argc,argv);
	Fl::add_timeout(2.0/3,timer_cb,&glf);
	
	return Fl::run();
}