// (c) Dinko Korunic, 36355514, kreator@fly.srk.fer.hr
// Zadatak broj 2 iz predmeta Racunalna grafika

#include <iostream.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.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, winsx, winsy;
	public:
		Display *disp;
		Window win;
		GC gc;
		XEvent ev;
		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;
}

struct Node_t
{
	int x, y;	// node type
};

struct Poly_t
{
	int CoordCount;		// broj koordinata poligona
	Node_t *PolyPtr;	// pokazivac na matricu sa koordinatama poligona
	Node_t *PointPtr;	// pokazivac na matricu sa koordinatama tocke
}; 

class MyDraw2 : public MyDisplay
{
	Poly_t MyPolyPtr;
	long *a, *b, *c;
	int xmin, xmax, ymin, ymax;
	void MyInit(void);
	void MyCalcCoef(void);
	void MyCheckPointPoly(void);
	void MyPolyFill(void);
	void MyWait(void);
	void MyDrawPoly(void);
	public:
		MyDraw2(Poly_t tmpSrc);
};

MyDraw2::MyDraw2(Poly_t tmpSrc) : MyPolyPtr(tmpSrc)
{
	MyInit();
	MyDrawPoly();
	MyCalcCoef();
	MyCheckPointPoly();
	XFlush(disp);
	MyWait();
	MyPolyFill();
	XFlush(disp);
	MyWait();
}

void MyDraw2::MyInit(void)
{
	// nadjemo ymin, ymax, xmin, xmax
	int i, tmpP;

	xmin=xmax=MyPolyPtr.PolyPtr[0].x;
	ymin=ymax=MyPolyPtr.PolyPtr[0].y;
	for(i=0; i<MyPolyPtr.CoordCount; i++)
	{
		if ((tmpP=MyPolyPtr.PolyPtr[i].x)>xmax) xmax=tmpP;
		if (tmpP<xmin) xmin=tmpP;
		if ((tmpP=MyPolyPtr.PolyPtr[i].y)>ymax) ymax=tmpP;
		if (tmpP<ymin) ymin=tmpP;
	}
}

void MyDraw2::MyCalcCoef(void)
{
	// izracunavanje koeficijenata jednadzbi bridova
	int crdcnt=MyPolyPtr.CoordCount;
	a=new long[crdcnt];
	b=new long[crdcnt];
	c=new long[crdcnt];
	for(int i=0; i<crdcnt; ++i)
	{
		a[i]=MyPolyPtr.PolyPtr[i].y-MyPolyPtr.PolyPtr[i+1].y;
		b[i]=-MyPolyPtr.PolyPtr[i].x+MyPolyPtr.PolyPtr[i+1].x;
		c[i]=MyPolyPtr.PolyPtr[i].x*MyPolyPtr.PolyPtr[i+1].y-
			MyPolyPtr.PolyPtr[i+1].x*MyPolyPtr.PolyPtr[i].y;
	}
}

void MyDraw2::MyCheckPointPoly(void)
{
	// provjera polozaja tocke V
	int x1=MyPolyPtr.PointPtr[0].x, y1=MyPolyPtr.PointPtr[0].y, i;
	for (i=0; i<MyPolyPtr.CoordCount; ++i)
	{
		if (x1*a[i]+y1*b[i]+c[i]>0)
		{
			cout << "Tocka V je izvan poligona" << endl;
			break;
		}
	}
	if (i==MyPolyPtr.CoordCount)
		cout << "Tocka V je unutar poligona" << endl;
	// i nacrtaj tocku!
	XDrawPoint(disp, win, gc, x1, y1);
}

void MyDraw2::MyPolyFill(void)
{
	// punjenje poligona
	int L, D, x11, y0, i;
	for (y0=ymin; y0<=ymax; ++y0)
	{
		L=xmin;
		D=xmax;
		for (i=0; i<MyPolyPtr.CoordCount; ++i)
		{
			if(a[i])
			{
				x11=-b[i]*y0/a[i]-c[i]/a[i];
				if (MyPolyPtr.PolyPtr[i].y
					<MyPolyPtr.PolyPtr[i+1].y
						&& x11>L)
					L=x11;
				if (MyPolyPtr.PolyPtr[i].y
					>=MyPolyPtr.PolyPtr[i+1].y
						&& x11<D)
					D=x11;
			}
		}
		if (L<D)
			XDrawLine(disp, win, gc, L, y0, D, y0);
	}
}

void MyDraw2::MyWait(void)
{
	// postavi wait na keypress
	XSelectInput(disp, win, KeyPressMask | ExposureMask);
	while(1)
	{
		XNextEvent(disp, &ev);
		if (ev.type==KeyPress) break;
	}
}

void MyDraw2::MyDrawPoly(void)
{
	int i;
	for (i=0; i<MyPolyPtr.CoordCount; i++)
	{
		XDrawLine(disp, win, gc, MyPolyPtr.PolyPtr[i].x,
			MyPolyPtr.PolyPtr[i].y, MyPolyPtr.PolyPtr[i+1].x,
			MyPolyPtr.PolyPtr[i+1].y);
	}
}

Poly_t MyAllInput(void)
{
	Poly_t tmpPolyPtr;
	// unos broja koordinata
	do
	{
		cout << "Unesi broj vrhova n konveksnog poligona ";
		cin >> tmpPolyPtr.CoordCount;
	} while (tmpPolyPtr.CoordCount<3);
	// alociraj prostor za n vrhova
	tmpPolyPtr.PolyPtr=new Node_t[tmpPolyPtr.CoordCount+1];
	int i;
	for (i=0; i<tmpPolyPtr.CoordCount; i++)
	{
		cout << "Unesi x,y tocke #" << i+1 << " ";
		cin >> tmpPolyPtr.PolyPtr[i].x;
		cin >> tmpPolyPtr.PolyPtr[i].y;
	}
	tmpPolyPtr.PolyPtr[i]=tmpPolyPtr.PolyPtr[0];
	tmpPolyPtr.PointPtr=new Node_t[1];	
	cout << "Unesi x,y koordinate tocke V(x1,y1) ";
	cin >> tmpPolyPtr.PointPtr[0].x;
	cin >> tmpPolyPtr.PointPtr[0].y;
	return tmpPolyPtr;
}

int main(void)
{
	MyDraw2 MyDraw2Object(MyAllInput());
	return EXIT_SUCCESS;
}