/*************************************
*                                    *
*   Some skeletal graphics commands  *
*   J. Mallinckrodt, Oct. 1999       *
*                                    *
************************************/
								// Header files
#include <graphics.h>
								// Prototypes
int initialize_graphics(void);				// Go into graphics mode
void setup_graphics(void)					// Set up graphics variables
void plot(void);							// Do the plotting
int xscr(float x);						// x screen conversion
int yscr(float y);						// y screen conversion

								// Global variables
int maxx,maxy;							// Set by initialize_graphics
int  xminscr,xrangescr,yminscr,yrangescr;			// Pixel range values
float xmin,xrange,ymin,yrange;				// Physical range values
float x_old,y_old,x_new,y_new					// Physical values to plot

int main(void)                  			// Start of main routine
{
...
	initialize_graphics();
	setup_graphics();
...
	outtextxy(0,140,"Press any key");
	outtextxy(0,150,"   to exit");
	getch();
	closegraph();
}								// End of main routine

								// Functions

/****************************************************************/

int initialize_graphics(void)
{
  int graphdriver=DETECT,graphmode,error_code;	// Local variable declarations
								// The primary graphics init call
  initgraph(&graphdriver,&graphmode,"c:/tc3/bgi");
  error_code=graphresult();       			// Set error code

								//See if there were any problems
  if(error_code != grOk)            		// and if so ...
  return -1;                      			// ... set error return value

								// See if an EGA or VGA graphics
								// driver was found and if not ...
  if ((graphdriver != EGA) && (graphdriver != VGA))
  {
    closegraph();              			// ... close graphics
    return 0;                     			// ... and return error code
  }

  maxx=getmaxx(),              		     	// Otherwise set screen size
  maxy=getmaxy();
  return 1;                       		 	// and return "O.K."
}


/****************************************************************/

void setup_graphics(void)
{
  xminscr= ... ;					// Minimum horizontal pixel
  xrangescr= ...;					// Horizontal pixel range 
  xmin= ...;					// Minimum physical "x" value
  xrange= ...;					// Range of physical "x" values
  yminscr= ...;					// Minimum vertical pixel
  yrangescr= ...;					// Vertical pixel range 
  ymin= ...;					// Minimum physical "y" value
  yrange= ...;					// Range of physical "y" values

  // Plus any other graphics commands to draw and label axes, 
  // print titles or legends, etc.  E.g.,

  setcolor(15)
  sprintf(text,"T = %5.2f",T);
  outtextxy(90,60,text);

}

/****************************************************************/

void plot(void)
{
  setcolor(plotcolor);
  line(xscr(x_old),yscr(y_old),xscr(x_new),yscr(y_new));

// or

  putpixel(xscr(x_new),yscr(y_new),plotcolor);

}

/****************************************************************/

int xscr(float x)
{
  return xminscr + xrangescr * (x-xmin)/xrange;
}

/****************************************************************/

int yscr(float y)
{
  return yminscr - yrangescr * (y-ymin)/yrange;
}