/*  Plot2.cpp

    Revised version of Plot1.cpp.
  
    Bruce M. Bolden
    October 23, 2006 
 *  --------------------------------------------------- 
 */

#include <iostream>
#include <iomanip>
#include <fstream>
#include <cstdlib>
#include <cmath>

using namespace std;

  //  Prototypes
void PlotLine( ofstream& fOut );
void Plot( ofstream& fOut, double x, double y, double yMin, double yMax );


int main()
{
   ofstream fOut( "plot1.out", ios::out ) ;
   if( !fOut )
   {
       cout << "Unable to open: \"plot1.out\"" << endl;
       exit( -1 );
   }

   PlotLine( fOut );     // draw a simple line

   fOut.close();

   return 0;
}


/*  PlotLine
 *
 *  Display the plot of a line.
 */
void PlotLine( ofstream& fOut )
{
   double  xMin  = -2.0;   //  range variables
   double  xMax  =  2.0;
   double  xStep = 0.5;

   double  yMin = -2.0;    //  plot scale
   double  yMax =  3.0;

   double  x, y;

   fOut << " Plot of y = x + 1\n" << endl;

   for( x = xMin ; x <= xMax ; x += xStep )
   {
       y = 1.0 * x + 1.0;

       Plot( fOut, x, y, yMin, yMax );
   }
}


/*  Plot
 *
 *  Display a value (y) if it lies between the minimum and maximum
 *  values (yMin and yMax).
 *  Output is written to the output stream referred to by fOut.
 */

void Plot( ofstream& fOut, double x, double y, double yMin, double yMax )
{
   const int bShowNumbers = 1;  //  show numbers on plot

   const int MAX_LINE   = 60;   //  total line length ~80 chars
   const int OFFSET     = 20;   //  offset from beginning of line
   const int DEC_PLACES =  3;   //  number of decimal places

   const char AXIS_SYMBOL = '|';
   const char PLOT_SYMBOL = '*';

   char  line[MAX_LINE+1];
   int index;                   //  location of "point" in line

       //  clear line
   for( int i = 0 ; i < MAX_LINE ; i++ )
       line[i] = ' ';
   line[MAX_LINE] = '\0';       //  "seal off" line 

       //  x-axis
   index = (int)(MAX_LINE * ((0.0-yMin)/(yMax-yMin)));
   if( index >= 0 && index < MAX_LINE )
   {
       line[index] = AXIS_SYMBOL;
   }

       //  scale and "plot" data point
   index = (int)(MAX_LINE * ((y-yMin)/(yMax-yMin)));
   //cout << index << endl;     //  testing aid

   if( index >= 0 && index < MAX_LINE )
   {
       line[index] = PLOT_SYMBOL; 
   }

       //  output
   if( !bShowNumbers )
   {
       fOut << setw(OFFSET);    //  this is unreachable 
   }
   else
   {
       fOut.setf( ios::fixed );
       fOut << setw(OFFSET/2) << setprecision(DEC_PLACES) << x;
       fOut << setw(OFFSET/2) << setprecision(DEC_PLACES) << y;
   }
   fOut << " | ";
   fOut << line << endl;        //  plot "line"
}