Based on fnord's answer, here is a Unity3D version with added ranges :
Code :
// golden angle in radians
static float Phi = Mathf.PI * ( 3f - Mathf.Sqrt( 5f ) );
static float Pi2 = Mathf.PI * 2;
public static Vector3 Point( float radius , int index , int total , float min = 0f, float max = 1f , float angleStartDeg = 0f, float angleRangeDeg = 360 )
{
// y goes from min (-) to max (+)
var y = ( ( index / ( total - 1f ) ) * ( max - min ) + min ) * 2f - 1f;
// golden angle increment
var theta = Phi * index ;
if( angleStartDeg != 0 || angleRangeDeg != 360 )
{
theta = ( theta % ( Pi2 ) ) ;
theta = theta < 0 ? theta + Pi2 : theta ;
var a1 = angleStartDeg * Mathf.Deg2Rad;
var a2 = angleRangeDeg * Mathf.Deg2Rad;
theta = theta * a2 / Pi2 + a1;
}
// https://stackoverflow.com/a/26127012/2496170
// radius at y
var rY = Mathf.Sqrt( 1 - y * y );
var x = Mathf.Cos( theta ) * rY;
var z = Mathf.Sin( theta ) * rY;
return new Vector3( x, y, z ) * radius;
}
Gist : https://gist.github.com/nukadelic/7449f0872f708065bc1afeb19df666f7/edit
Preview: