I don't think make-sphere-generator works with different axis lengths.

I haven't tested make-ball-generator, but since it relies on
make-sphere-generator, I suspect that it doesn't work with different
axis lengths, either.

Brad

On 8/3/20 10:35 PM, Bradley Lucier wrote:
> That's a very good concern.
>
> I'm including a test program here that shows that the points on an
> ellipse generated by (make-sphere-generator '#(10 2)) from sphere.scm
> are not distributed uniformly around the ellipse.  In other words,
> Arvydas's concerns are valid.
>
> If I generate 10,000 points on the ellipse, then on the top of the
> ellipse I find for points on the "top" of the ellipse, with y > 1.5,
> that the average distance between adjacent points is
>
>  > (average-distance top)
> .003781294690450104
>
> and on the "right" of the ellipse, with x > 8, the average distance
> between adjacent points is
>
>  > (average-distance right)
> .004584542133993673
>
> So I don't think (make-sphere-generator '#(10 2)) generates points
> uniformly on the ellipse.
>
> Brad
>
>
>
>
>
>
> On 7/16/20 4:14 PM, Arvydas Silanskas wrote:
>> Yes, that's how I'm picturing implementing it. But what I'm not sure
>> of is the quality of spacing between the points. Maybe unneededly, if
>> you say it's ok then it's ok, I just want to confirm you understand my
>> question. I attach a picture of my concern.
>>
>> 2020-07-16, kt, 21:33 Lucier, Bradley J <xxxxxx@purdue.edu
>> <mailto:xxxxxx@purdue.edu>> rašė:
>>
>>     Sorry, you meant standard deviation, not variance.
>>
>>      > On Jul 16, 2020, at 2:28 PM, Lucier, Bradley J <xxxxxx@purdue.edu
>>     <mailto:xxxxxx@purdue.edu>> wrote:
>>      >
>>      > I think you mean sqrt(A), etc. Brad
>>      >
>>      >> On Jul 16, 2020, at 2:14 PM, Linas Vepstas
>>     <xxxxxx@gmail.com <mailto:xxxxxx@gmail.com>> wrote:
>>      >>
>>      >> So, if the ellipse major axis lengths are A,B,C... then generate
>>     X,Y,Z with widths A,B,C..
>>
>