/************************************************************************************/
/*  Lathe city                                                                      */
/*  calculating the slicing of spherical (ball) shapes for manual lathe operations  */
/*                                      (c) U. Burghaus, 2010                       */
/* shown here is a program skelleton and not a complete and user friedly code       */
/* add graphics and data input/output procedures depending on the "C" compiler used */
/* or get the windows exe version from our on-line shop                             */
/**Start*****************************************************************************/

/* Header for graphic part of the program */
...

/* Header for numeric part of the program */
...
 

// stock parameters
float StockLength = 3.0;
float StockDiameter = 1.0;

// circle parameters
float x0 = 1.0; 
float y0 = 3.0;
float r=0.5;

// process parameters
float SliceThickness=0.02;
float StopAt=0.6;			// stop position for cuts, last slice
// the numbers given here are just an example, the program works for various geometries

// program parameters
float alfa;				// parameter for the circle
float AlfaStart;		// starting angle / starting (first) slice position
float alfa_sl;		    // current angle corresponding to the current slice
float alfa_sl_end;		// for inside geometries
float xcor;				// current positing of the slice
float CircleX[400];		// for plotting the circle
float CircleY[400];
float SlicePlot[100];   // plotting the slices
float SlicePlotEnd[100];// for inside geometries
float SlicePlotStart[100];// for inside geometries   
float SliceLength[100]; // calculated slice length for cuts with the lathe 
int   scaling;          // auto scaling on/off for graphics
int   NumberOfSlices;

// storr last slice table****************************************************
int CVICALLBACK save (...)
{
    int j,i; 
    FILE *fd; 
    char buffer[150];   														   
					  
    for (j=1;j<NumberOfSlices;j++) {
        strcat(buffer,"");												   
        sprintf(buffer, "#%d %10.3f",j,SliceLength[j]);
        fprintf(fd,"%s\n",buffer);
    }
            													
    ...
    return 0;
}


// print stock and cutting shape on screen**************************************************** 
int CVICALLBACK update (...)
{
int  i;
char message[20];  

	// plot stock/work piece
	GetCtrlVal(...); // get parameters  			
        PlotRectangle (...StockDiameter,  StockLength, ...);			 
	// plot center line
	PlotLine (...StockDiameter/2.0, 0, StockDiameter/2.0, StockLength, ...);			
	//plot circle
 	GetCtrlVal(...); // get parameters  
	PlotPoint (...x0, y0, ...); // mark center			 
	for (i=0; i<=359; i++) {
		alfa=(float)(i)*2*3.1415/360.0;
		CircleY[i]=y0+r*sin(alfa);
		CircleX[i]=x0+r*cos(alfa);  
	}

	PlotXY (...CircleX, CircleY ...);

	return 0;
}


// calculate slice table**************************************************** 
int CVICALLBACK slicing (...)
// one can also save the coordinates in a table and look up the slice length
{

int i; // slice number
int j;
								
   	// read parameters from user interface
   	...							    
	xcor = StockDiameter; // start sclicing from outside
	AlfaStart = 270.0/360.0*2*3.1415;  // start angle for quarter circle geometry    
	i=0; // data index																					   
				
	// simpler geometries
	if (y0 >= StockLength) {  // circle overlaps with the edge of stock piece
		while ((xcor > StopAt) & (((SliceThickness*i+(x0-StockDiameter))/r) < 1))										  
		{	
			// calculate angle for slice
			if (x0==StockDiameter) alfa_sl=asin(SliceThickness*i/r);  // quarter circle geometry
			if (x0>StockDiameter) alfa_sl=asin( (SliceThickness*i+(x0-StockDiameter))/r ); // circle segment 
			// calculate position on circle for the slice
			SlicePlot[i]=y0+r*sin(AlfaStart-alfa_sl);
			SliceLength[i]=StockLength-SlicePlot[i];
			// screen plot
			PlotRectangle (...
			 	StockDiameter-SliceThickness*i, StockLength, 	   // upper corner
			 	StockDiameter-SliceThickness*(i+1), SlicePlot[i],  // lower corner
			 	  ...);
			// go to next slice position
			xcor = xcor-SliceThickness;
			i++;
		}// end of while loop
	};// end of if statement
	// this section may be more tricky to understand
	// always the angles are used to calculate the slice positions since a circle is given by
	// a parameterization with the angle
	// most of these shapes are, however, nearly impossible to cut manually
	if (y0 < StockLength) {	   // circle entirely inside of stock piece, section cuts
				  // this is practical only for shallow cuts
		while ((xcor > StopAt) & (((SliceThickness*i+(x0-StockDiameter))/r) < 1))										  
		{																	 
			if (x0==StockDiameter) alfa_sl=asin(SliceThickness*i/r);
			if (x0>StockDiameter) alfa_sl=asin( (SliceThickness*i+(x0-StockDiameter))/r ); 
			SlicePlotStart[i]=y0+r*sin(AlfaStart-alfa_sl);
			// circle center at edge of stock, half circle geometry
			if (x0==StockDiameter) { alfa_sl_end =asin(SliceThickness*i/r)+3.1415;   
				     	         SlicePlotEnd[i]= y0+r*sin(AlfaStart-alfa_sl_end);
				     	       }
			// circle center outside of stock piece, circle section
			if (x0>StockDiameter) { alfa_sl_end=asin( (SliceThickness*i+(x0-StockDiameter))/r ) +3.1415; 
				     	                          SlicePlotEnd[i]= y0+r*sin(AlfaStart-alfa_sl_end);
				     	                          }                         
			SliceLength[i]=SlicePlotEnd[i]-SlicePlotStart[i];
		        PlotRectangle (...);
			xcor = xcor-SliceThickness;
			i++;
		}// wile end
	}; // if end
	// we may have overlooked some kind of odd geometry but the program should catch most of them		 															 	   
	NumberOfSlices = i;										 		  
																  
	return 0;													 	    
}

/**end*****************************************************************************/