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Subject: 
Re: Is it possible to use LDView as POV-Ray previewer?
Newsgroups: 
lugnet.cad.ray
Date: 
Tue, 6 Dec 2005 16:04:44 GMT
Viewed: 
15039 times
  
In lugnet.cad.ray, Travis Cobbs wrote:
> In lugnet.cad.ray, Lars C. Hassing wrote:
> > But perhaps it would be more convenient to have a -matrix option
> > to directly specify the camera matrix ?
> > I know POV supports the matrix keyword inside the camera.
> 
> I did some investigation (read: experimentation), and came to the conclusion
> that I'm not going to be able to produce a camera matrix that POV will accept.
> The problem is that I use floats in my matrix, and they're not accurate enough
> to produce results that POV will accept.  (It complains about things not being
> perpendicular.  It won't do this if you manually turn off the Vista buffer, but
> I get the impression that doing so will slow rendering down, and disable certain
> features.)
> 
> I was able to successfully generate a camera with the following settings,
> though:
> 
> location
> direction
> up
> right
> angle
> 
> I cheated and made small adjustments to my up and right vectors to force them to
> be perpendicular to my direction vector in double precision.  Fortunately, up
> and right don't have to be perpendicular to each other, since having all three
> vectors be perpendicular in double precision would have been a lot more
> difficult.
> 
> You already support angle and location.  Is there any chance you can support
> command-line specification of the direction, up, and right vectors?

Well, yes, but could you try generating these parameters in stead:
   location
   sky
   look_at
   angle
These should be adequate to fully describe the camera.
ldglite uses them http://ldglite.sourceforge.net/ldglitepov.html
and I have already made a -csky option.

My impression has always been that you should not tamper with
the up and right vectors, only for changing the aspect radio.
I have already added an option for aspect ratio that modifies
the right vector.
So, if you could generate the sky vector that would be great.
/Lars
Good links:
http://library.thinkquest.org/3285/language/camera.html
http://www.nada.kth.se/hacks/doc/PoVRay/pov114.html



Message has 2 Replies:
  Re: Is it possible to use LDView as POV-Ray previewer?
 
(...) I can do that. Unless I'm badly mistaken, my existing up will work fine as a sky vector. (...) Reading between the lines of the descriptions of the various camera settings, it really looks like POV-Ray automatically generates direction, up, (...) (21 years ago, 6-Dec-05, to lugnet.cad.ray)
  Re: Is it possible to use LDView as POV-Ray previewer?
 
In lugnet.cad.ray, Lars C. Hassing wrote: > Well, yes, but could you try generating these parameters in stead: > location > sky > lookat > angle OK, I got it working. Here's my camera: camera #declare ASPECT = 4/3; location < (...) (21 years ago, 9-Dec-05, to lugnet.cad.ray, FTX)

Message is in Reply To:
  Re: Is it possible to use LDView as POV-Ray previewer?
 
(...) I did some investigation (read: experimentation), and came to the conclusion that I'm not going to be able to produce a camera matrix that POV will accept. The problem is that I use floats in my matrix, and they're not accurate enough to (...) (21 years ago, 6-Dec-05, to lugnet.cad.ray)

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