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/* name: dots.c */
/* author: J. Michael Word (port from dcr and mez fortran code) */
/* date written: 2/20/96 */
/* purpose: generate points on a sphere */
/*****************************************************************/
/* NOTICE: This is free software and the source code is freely */
/* available. You are free to redistribute or modify under the */
/* conditions that (1) this notice is not removed or modified */
/* in any way and (2) any modified versions of the program are */
/* also available for free. */
/* ** Absolutely no Warranty ** */
/* Copyright (C) 1999 J. Michael Word */
/*****************************************************************/
#include <stdlib.h>
#include <math.h>
#include "dots.h"
#define PI 3.14159265359
void dotSphere(pointSet *set, float radius, float density) {
int m;
if (set) {
m = estNumDots(radius, density);
set->n = 0;
set->p = (point3d *)malloc(m*sizeof(point3d));
if (set->p) {
set->n = makeDots(radius, set->p, m);
}
}
}
void freeDotSphere(pointSet *set){
if (set) {
set->n = 0;
if (set->p) {
free(set->p);
set->p = NULL;
}
}
}
int estNumDots(float radius, float density) {
float sizefact = 1.0;
/* overestimate of the number of dots */
return (int)floor(4.0 * PI * density * sizefact * (radius * radius));
}
int makeDots(float radius, point3d points[], int maxpnts) {
float offset = 0.2;
double ang, cosang, sinang, phi, theta, xy0, x0, y0, z0;
int i, j, k, odd, nequator, nvert, nhoriz;
nequator = (int)floor(sqrt(maxpnts * PI));
odd = 1;
ang = 5.0 * PI / 360.0;
cosang = cos(ang);
sinang = sin(ang);
i = 0;
nvert = nequator / 2;
for (j = 0; j <= nvert; j++) {
phi = (PI * j) / nvert;
z0 = cos(phi) * radius;
xy0= sin(phi) * radius;
nhoriz = (int)floor(nequator * sin(phi));
if (nhoriz < 1) nhoriz = 1;
for (k = 0; k < nhoriz; k++) {
if(odd) {theta = (2.0 * PI * k + offset)/nhoriz; }
else {theta = (2.0 * PI * k )/nhoriz; }
x0 = cos(theta) * xy0;
y0 = sin(theta) * xy0;
if (i >= maxpnts) return i;
points[i].x = x0;
points[i].y = y0*cosang - z0*sinang;
points[i].z = y0*sinang + z0*cosang;
i++;
}
odd = !odd;
}
return i;
}
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