//////////////////////////////////////////////////////////////////
//
//	sierpinski.cpp
//
//	Started in Pascal by Jeff Ondich on 2/19/96
//	Last modified 11/10/99
//
//	This program uses the g2 graphics library,
//	and should be compiled like so:
//
//	g++ -o sierpinski sierpinski.cpp -L/usr/X11R6/lib -lm -lX11 -lgd -lg2
//	
///////////////////////////////////////////////////////////////////

#include <iostream>
#include <g2++.h>
#include <g2_X11++.h>

const int windowHeight= 800;
const int windowWidth = 800;

void DrawTriangle( int window, double left, double bottom, double legLength );
void DrawPicture( int window, double x, double y, int depth, double legLength );

int main()
{
	int window = g2_open_X11( windowWidth, windowHeight );

	int black_ink = g2_ink( window, 0, 0, 0 );
	int white_ink = g2_ink( window, 1, 1, 1 );

	g2_set_background( window, white_ink );
	g2_pen( window, black_ink );


	int			howDeep = 6;
	double		howWide = 200;
	double		startingX = 300;
	double		startingY = 300;
	
	DrawPicture( window, startingX, startingY, howDeep, howWide );
	
	cin.ignore();
	
	return( 0 );
}


 
///////////////////////////////////////////////////////////////////
//	DrawTriangle draws the 45-45-90 triangle whose legs
//	have length legLength and extend left and down from
//	the point upperRight.
///////////////////////////////////////////////////////////////////

void DrawTriangle( int window, double left, double bottom, double legLength )
{
	g2_move( window, left, bottom );
	g2_line_to( window, left + legLength, bottom );
	g2_line_to( window, left, bottom + legLength );
	g2_line_to( window, left, bottom );
}



///////////////////////////////////////////////////////////////////
//	DrawPicture draws a picture.  Note the recursion.
///////////////////////////////////////////////////////////////////

void DrawPicture( int window, double x, double y, int depth, double legLength )
{

	if( depth > 0 )
	{
		DrawTriangle( window, x, y, legLength ); // LINE A

		double			halfLeg = legLength / 2;
		double			newX, newY;

		newX = x - halfLeg;
		newY = y + halfLeg;
		DrawPicture( window, newX, newY, depth-1, halfLeg );
		
		newX = x + halfLeg;
		newY = y - halfLeg;
		DrawPicture( window, newX, newY, depth-1, halfLeg );

		newX = x + halfLeg;
		newY = y + halfLeg;		
		DrawPicture( window, newX, newY, depth-1, halfLeg );

		// LINE B
	}
}