//-------------------------------------------------------------------
//	randwalk.cpp
//
//	This program exhibits a simple "random walk" animation that
//	shows a molecule moving left or right with equal liklihood.	
//
//		compile using:  $ g++ randwalk.cpp -o randwalk
//		execute using:  $ ./randwalk
//
//	programmer: ALLAN CRUSE
//	written on: 25 JAN 2011
//-------------------------------------------------------------------

#include <stdio.h>	// for printf() 
#include <stdlib.h>	// for random() 
#include <unistd.h>	// for usleep() 
#include <time.h>	// for time()

int main( int argc, char **argv )
{
	// prepare a blank screen with the cursor hidden 
	printf( "\e[H\e[J" );	// clear the screen 	
	printf( "\e[?25l" ); 	// hide the cursor
	fflush( stdout );

	// seed the random number generator
	srandom( time( 0 ) );

	// initialize the annimation
	int	row = 12, col = 40;	
	printf( "\e[%d;%dH%c", row, col, 'o' ); 
	fflush( stdout );
	
	// perform the random walk 
	for (int i = 0; i < 100; i++)
		{
		usleep( 200000 );	// delay 200 milliseconds 
		printf( "\e[%d;%dH%c", row, col, ' ' ); fflush( stdout );
		int	x = random() % 2;
		if ( x > 0 ) ++col; else --col;
		printf( "\e[%d;%dH%c", row, col, 'o' ); fflush( stdout );
		}

	// prepare cursor for exit and restore its visibility  
	printf( "\e[24;0H" );	// move cursor to bottom of screen
	printf( "\e[?25h" );	// show the cursor
	fflush( stdout );	
}