// (c) Dinko Korunic, 36355514, kreator@fly.srk.fer.hr
// Zadatak broj 5 iz predmeta Racunalna grafika

#include <iostream.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <math.h>

class MyDisplay
{
	// klasa MyDisplay u kojoj se nalaze inicijalizacijske xlib
	// rutine, kao i postavljanje background i foreground boje, itd.
	XGCValues gcv;
	unsigned long wp, bp;
	int screen, winx, winy;
	public:
		Display *disp;
		Window win;
		GC gc;
		XEvent ev;
		void MyWait(void);
		int winsx, winsy;
		MyDisplay(int _winx, int _winy, int _winsx,
				int _winsy);
		~MyDisplay();
};

MyDisplay::MyDisplay(int _winx=0, int _winy=0, 
	int _winsx=400, int _winsy=400) :
	winx(_winx), winy(_winy), winsx(_winsx), winsy(_winsy)
{

	// konstruktor koji sluzi za misc. inicijalizaciju
	cout << "Initialising graphic subsystem.." << endl;
	// otvaranje displaya
	if ((disp=XOpenDisplay(NULL))==NULL)
	{
		cerr << "I can't open display." << endl;
		exit(EXIT_FAILURE);
	}
	screen=DefaultScreen(disp);
	// stvaranje prototipnog prozora
	win=XCreateSimpleWindow(disp, DefaultRootWindow(disp),
		winx, winy, winsx, winsy, 1, wp=WhitePixel(disp, screen),
		bp=BlackPixel(disp, screen));
	XSelectInput(disp, win, StructureNotifyMask | KeyPressMask
		| ExposureMask);
	// mapiranje prozora
	XMapWindow(disp, win);
	while(1)
	{
		// cekaj dok nije gotovo
		XNextEvent(disp, &ev);
		if (ev.type==MapNotify) break;
	}
	gcv.foreground=wp;
	gcv.background=bp;
	// stvori gc
	gc=XCreateGC(disp, win, GCForeground | GCBackground, &gcv);
	cout << "done." << endl;
}

MyDisplay::~MyDisplay()
{
	// destruktor za graficki engine
	cout << "Shutting graphic subsystem.." << endl;
	XFreeGC(disp, gc);
	XDestroyWindow(disp, win);
	XCloseDisplay(disp);
	cout << "done." << endl;
}

void MyDisplay::MyWait(void)
{
	// postavi wait na keypress
	XSelectInput(disp, win, KeyPressMask | ExposureMask);
	while(1)
	{
		XNextEvent(disp, &ev);
		if (ev.type==KeyPress) break;
	}
}

struct Vrh
{
// vrh poligona
	int x, y, z; // koordinate u sustavu scene
	double xo, yo, zo; // koordinate u sustavu oka
	int xp, yp; // koordinate prikaza
};

struct Polig
{
// poligon
	int n; // broj vrhova poligona
	Vrh *Polje; // polje vrhova poligona orijentirane u smjeru
			// kazaljke na satu
	float A, B, C, D; // koeficijenti ravnine u kojoj lezi poligon
};

class MyDraw5 : public MyDisplay
{
	Vrh Ociste;
	Vrh Glediste;
	Polig Poligon;
	public:
		void TransformView(Vrh *);
		void Projection(Vrh *);
		void Input(void);
		MyDraw5();
};

MyDraw5::MyDraw5()
{
	Input();
	int i;
	for (i=0; i<Poligon.n; ++i)
	{
		TransformView(&Poligon.Polje[i]);
		Projection(&Poligon.Polje[i]);
	}
//ispis -- koordinatni sustav treba postaviti na sredinu ekrana
	for (i=0; i<Poligon.n; ++i)
	{
		XDrawLine(disp, win, gc, winsx/2+Poligon.Polje[i].xp,
			winsy/2+Poligon.Polje[i].yp, 
			winsx/2+Poligon.Polje[(i+1)%Poligon.n].xp,
			winsy/2+Poligon.Polje[(i+1)%Poligon.n].yp);
	}
	XFlush(disp);
	MyWait();
}

void MyDraw5::TransformView(Vrh *tmpV)
{
	double cosa, sina, cosb, sinb, xg1, yg1, zg1, xg2;
	xg1=Glediste.x-Ociste.x;
	yg1=Glediste.y-Ociste.y;
	zg1=Glediste.z-Ociste.z;
	xg2=sqrt(xg1*xg1+yg1*yg1);
	sina=yg1/xg2;
	cosa=xg1/xg2;
	sinb=xg2/sqrt(xg1*xg1+yg1*yg1+zg1*zg1);
	cosb=zg1/sqrt(xg1*xg1+yg1*yg1+zg1*zg1);
	tmpV->xo=tmpV->x*sina-tmpV->y*cosa-Ociste.x*sina+Ociste.y*cosa;
	tmpV->yo=-tmpV->x*cosa*cosb-tmpV->y*sina*cosb+tmpV->z*sinb
		+Ociste.x*cosa*cosb+Ociste.y*sina*cosb-Ociste.z*sinb;
	tmpV->zo=tmpV->x*cosa*sinb+tmpV->y*sina*sinb+tmpV->z*cosb
		-Ociste.x*cosa*sinb-Ociste.y*sina*sinb-Ociste.z*cosb;
	Glediste.xo=Glediste.yo=0;
	Glediste.zo=sqrt(xg1*xg1+yg1*yg1+zg1*zg1);
}

void MyDraw5::Projection(Vrh *tmpV)
{
	tmpV->xp=tmpV->xo/tmpV->zo*Glediste.zo;
	tmpV->yp=tmpV->yo/tmpV->zo*Glediste.zo;
}

void MyDraw5::Input(void)
{
// procitaj koordinate ocista i gledista
	cout << "Koordinate ocista" << endl;
	cin >> Ociste.x;
	cin >> Ociste.y;
	cin >> Ociste.z;
	cout << "Koordinate gledista" << endl;
	cin >> Glediste.x;
	cin >> Glediste.y;
	cin >> Glediste.z;
// procitati broj vrhova poligona
	cout << "Broj vrhova poligona" << endl;
	cin >> Poligon.n;
	Poligon.Polje=new Vrh[Poligon.n];
	int i;
	cout << "Unos koordinata" << endl;
	for (i=0; i<Poligon.n; ++i)
	{
		cin >> Poligon.Polje[i].x;
		cin >> Poligon.Polje[i].y;
		cin >> Poligon.Polje[i].z;
	}
}

int main(void)
{
	MyDraw5 MyOb;
	return EXIT_SUCCESS;
}