On 11/6/24 10:51, Bald Eagle wrote:

Hi.

> So - you've got a central cubelet surrounded by 26 other neighbor cubelets.
> Is the central cubelet (off)set at <2, 2, 2>?
> 

The evaluation point is in the center cubelet of a larger 5x5x5 cube(*) 
of cubelets. The center point of all cubelets is offset by a random-ish 
still within each cubelet as the 'Voronoi' points.

(*) Official POV-Ray does an optimization to calculate only 81 cubelet 
offset vectors & yuqk might later adopt something similar (**). The 
current yuqk crackle is set up for up to 7x7x7 as I wanted to experiment 
with other crackle options at some point.

(**) - I think OK to a high probability & for our crackle pattern, but 
not quite completely "right".

> 
> Recalling some of your other posts - the pattern looks very "cubic" - rather
> than a typical Voronoi pattern.
> 

Allowing for some tuning differences, both the official POV-Ray and yuqk 
methods are cubelets forming a cube based (not pure Voronoi, points 
anywhere implementations), so yes this underlying structure is noticeable.

I suspect you are more noticing yuqk's new ip_strength vector multiplier 
for the offsets, which can be <1.0 for any of the components. At a 
strength of 0.0 the cube of cublets structure is completely on display.

> Also, have you thought about allowing user-defined distance metrics (Euclidean,
> Manhattan, Minkowski, etc.) for generating the underlying pattern?

Sure, the first two are already implemented as metrics 2 and 1 (***). 
I'm not completely sure what you mean by minkowski. I'm familiar with 
minkowski sum and difference with respect to shapes. Some options today 
give a similar look, but the devil is in the details.

(***) The official POV-Ray code both implements a power metric and 
defined the exponent for it by using metrics values other than 1 or 2. I 
thought this ugly, especially given I wanted to add more metrics.

So in yuqk there is an ip_metric 0, which means use a power metric with 
which a new ip_exponent keyword for the exponent to use. This allows 
ip_metric to be extended. I've only added one in (3) for four total in 
0,1,2,3 - but there are plans to try others.

User defined. The ip_form vector offers some control. Each component is 
a +- distance multiplier for the three distance measures taken (The 
three closest points to the evaluation point).

Bill P.

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