POV-Ray : Newsgroups : povray.general : PoV-Ray 3.5: Sin() works incorrect Server Time
25 Dec 2024 01:33:00 EST (-0500)
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From: The Brain
Subject: PoV-Ray 3.5: Sin() works incorrect
Date: 24 May 2003 04:54:06
Message: <3ecf332e@news.povray.org>
Hi.

This is my first Message to news.povray, so be nice ;). I use Pov-Ray for
Windows 98 3.5 and try to make my first animations. My Plan is to rotate the
cap point of a cylinder around the z-axis, while the base point is <0, 0, 0>
Because I want to know the new coordinates of the cap point, i can't simply
use the rotate-command, right?

However, I have to work with the sin()-Function. But my PoV-Ray caculates
the most stupid coordinates I ever seen when I use it. I checked my formulas
100 times, and so I'm shure that it is correct.

Now to my question(s):
How can i rotate a cylinder manually without the sin()-command?
And (because the answer of the first question will be: its impossible) can I
detect the new coordinates of the cap point when I use the rotate-command?


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From: Micha Riser
Subject: Re: PoV-Ray 3.5: Sin() works incorrect
Date: 24 May 2003 05:07:28
Message: <3ecf3650@news.povray.org>
I have the strong feeling that you are working with angles in degree while
POV-Ray wants them in radians for the sin() function!

- Micha

-- 
POV-Ray Objects Collection: http://objects.povworld.org


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From: ingo
Subject: Re: PoV-Ray 3.5: Sin() works incorrect
Date: 24 May 2003 05:12:48
Message: <Xns93857295E1104seed7@povray.org>
in news:3ecf332e@news.povray.org The Brain wrote:

> can I
> detect the new coordinates of the cap point when I use the
> rotate-command? 
> 

have a look at the vector function vrotate(A,B) in "6.1.4.6  Vector 
Functions"

Ingo


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From: The Brain
Subject: Re: PoV-Ray 3.5: Sin() works incorrect
Date: 24 May 2003 05:15:30
Message: <3ecf3832@news.povray.org>
Oops, right ^^

Thanks


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From: The Brain
Subject: Re: PoV-Ray 3.5: Sin() works incorrect
Date: 24 May 2003 05:42:44
Message: <3ecf3e94@news.povray.org>
aah, this is is exactly that what I need. Thx.


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From: The Brain
Subject: What if...
Date: 24 May 2003 06:11:20
Message: <3ecf4548@news.povray.org>
And what if I use the Rotate_Around_Trans macro instead of the simple
rotate?


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From: ingo
Subject: Re: What if...
Date: 24 May 2003 06:41:17
Message: <Xns9385819674110seed7@povray.org>
in news:3ecf4548@news.povray.org The Brain wrote:

> And what if I use the Rotate_Around_Trans macro instead of the simple
> rotate?
> 

Brain,

If you take a look at the actual macro, you'll see that it is just a 
'simple' rotate plus two translations.

Actually, I'm starting to wonder what it is you want to acheive? In 
youre first post you want to rotate a cylinder, with one cap in the 
origin, around the z-axis:

cylinder {
  <0,0,0>, <cap_somewhere>, 1
  rotate <0,0,clock*360>
}

Then you want to know the position of the other cap after rotation:

#declare CapPosition = vrotate(<cap_somewhere>,<0,0,clock*360>)

Now you want to use Rotate_Around_Trans, so ...?

Ingo


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From: The Brain
Subject: Re: What if...
Date: 24 May 2003 06:46:39
Message: <3ecf4d8f@news.povray.org>
Thx. As from now I wont ask stupid questions.
I want to make several clinders, linked with spheres.


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From: ingo
Subject: Re: What if...
Date: 24 May 2003 06:55:08
Message: <Xns938583EFA4929seed7@povray.org>
in news:3ecf4d8f@news.povray.org The Brain wrote:

> Thx. As from now I wont ask stupid questions.

There are no stupid questions. It's just sometimes difficult to 
interpret what's going on in someone others brain through a line in a 
message.

> I want to make several clinders, linked with spheres.

You could put a sphere and a cylinder in a union, that way you don't 
have to use vrotate.

union {
  cylinder {
    <0,0,0>, <other_cap>,1
  }
  sphere {
    <somewhere_and_related_to_other_cap>,1
  }
  rotate <0,0,360*clock>
}

Ingo


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From: Hughes, B 
Subject: Re: What if...
Date: 24 May 2003 07:03:38
Message: <3ecf518a$1@news.povray.org>
"The Brain" <rag### [at] univalde> wrote in message
news:3ecf4d8f@news.povray.org...
> Thx. As from now I wont ask stupid questions.
> I want to make several cylinders, linked with spheres.

Gee, try not to get paranoid or anything  ;-)  ingo was just wondering, I'm
sure.

But anyway, stupid questions belong in the povray.newusers group. Only
joking! Second time within a matter of minutes. Seriously though, it seems
you might have actually overlooked that group so thought I'd point it out.
And if you believe the question merits asking in povray.general instead
anyway, at least you didn't post it to povray.advanced. :-)

Bob H.


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