POV-Ray : Newsgroups : povray.general : Precision problems? : Re: Precision problems? Server Time14 Apr 2024 04:34:30 EDT (-0400)
 Re: Precision problems?
 From: kurtz le pirate Date: 26 Jan 2024 12:54:18 Message: <65b3f1ca\$1@news.povray.org>
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"headline": "Re: Precision problems?",
"dateCreated": "2024-01-26T17:54:18+00:00",
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On 26/01/2024 17:01, Cousin Ricky wrote:
> Ilya Razmanov <ily### [at] gmailcom> wrote:
>> I have a weird problems with some prisms. Please see the file attached,
>> it's tiny example. As you can see, both hexagonal prisms and their
>> translations are calculated using school math; moreover, when it comes
>> to irrational floats, the same values are used whenever possible via
>> declaring the variable, so it have no choice but match. Still, there is
>> a gap between objects in vertical direction.
>>
>> I'm out of ideas regarding the cause of it. Any inspiration?
>
> The geometry of the hexagons is off.  Replacing all occurrences of 0.25 with
> revsqrtof3/2 will fix it.
>
>

Yes, som error in yours points.

Assuming that the first point of the prism is good : <-0.5,0.25>

We can easily calculate the radius of the center containing the hexagon

sqrt(-0.50*-0.50 + 0.25*0.25) = 0.559017 = r

Calculating all the points gives :
< 0.0000,  0.5590>
< 0.4841,  0.2795>
< 0.4841, -0.2795>
< 0.0000, -0.5590>
<-0.4841, -0.2795>
<-0.4841,  0.2795>

with :
x = r*sin(radians(a));
z = r*cos(radians(a));

'a' is the angle : 0, 60, 120, 180, 240, 300

Drawing these points near your prism give the attached image where the
different positions of the points are clearly visible.

Hope that help

--
Kurtz le pirate
Compagnie de la Banquise
```

Attachments:
Download 'prizm test 3.png' (3 KB)

Preview of image 'prizm test 3.png'