/**
 * @file        sphere.c
 * @author      Robert S Laramee
 * @version     1.0
 * @see         build_mr_v3.c, expand.c
 * <P>
 * start date   Sat 29 May 1999
 * finish date
 * <P>
 * Description  This program generates an isosurface(s) in the shape of a 
 *              sphere.  It outputs the data in a format suitable for input
 * for build_mr_v3.c
 * compile using:
 * gcc -Wall sphere.c -o sphere.exe -lm
 */

#include <stdio.h>
#include <math.h>  /*  for pow(), sqrt()  */

double pow(double x, double y);

/*  dimensions constants  */  
#define XROWS    65
#define YCOLUMNS 65
#define ZLAYERS  65

/**
 * note: 
 * 8 x 8 x 8    = 512
 * 9 x 9 x 9    = 729
 * 16 x 16 x 16 = 4096
 * 32 x 32 x 32 = 32,768
 * 33 x 33 x 33 = 35,937
 */
int main(int argc, char *argv[]) {

    int i   = 0;
    int sum = 0;
    int x,y,z;
    float data[XROWS * YCOLUMNS * ZLAYERS];
    
    /*  initialize the data set to 0  */
    for(z = 0; z < ZLAYERS; z++) {
	for(y = 0; y < YCOLUMNS; y++) {
	    for(x = 0; x < XROWS; x++) {

		data[i] = 0.0;
		i++;        /*  i++ --> "Bus error"  */
	    }
	}
    }

    i = 0;
    /*  populate the data set  */
    for(z = 0; z < ZLAYERS; z++) {
	for(y = 0; y < YCOLUMNS; y++) {
	    for(x = 0; x < XROWS; x++) {

		sum = ( (x - (XROWS   /2)) * (x - (XROWS   /2)) + 
			(y - (YCOLUMNS/2)) * (y - (YCOLUMNS/2)) + 
			(z - (ZLAYERS /2)) * (z - (ZLAYERS /2))   
		      );

		if ( sum < (XROWS/2)*(XROWS/2) ) {
		    data[i] = 1.0;
		}
		i++;
	    }
	}
    }

    i = 0;
    /*  print the data set  */
    for(z = 0; z < ZLAYERS; z++) {
	for(y = 0; y < YCOLUMNS; y++) {
	    for(x = 0; x < XROWS; x++) {

		printf("%f\n", data[i]);
		i++;
	    }
	}
    }
    return 0;
}