POV-Ray : Newsgroups : povray.general : ImageWidth not declared? : Re: ImageWidth not declared? Server Time
15 Jul 2025 00:07:12 EDT (-0400)
  Re: ImageWidth not declared?  
From: clipka
Date: 16 Jan 2018 03:24:05
Message: <5a5db6a5$1@news.povray.org>
Am 15.01.2018 um 18:56 schrieb William F Pokorny:

> Unsure the 3.6 docs will be touched at this point. The 3.7/3.8
> equivalent page:
> 
> http://wiki.povray.org/content/Knowledgebase:Language_Questions_and_Tips#Topic_19
> 
> 
> has been updated with the correct keywords. It also strongly discourages
> use of the keywords to a degree with which I don't agree.

You're not the only one.

That's why POV-Ray 3.8.0-alpha will even use `right
x*image_width/image_height` as the default (provided you specify
`#version 3.8` at the very start of the file).


The reasons stated do have their merit, but I think they warrant no more
than to just advise some caution.

It should also be noted that scene authors worried about the issues can
use a construct like the following to enforce the intended aspect ratio:

    #if (image_width/image_height != 4/3)
      #error "Scene is designed for 4:3 aspect ratio!\n"
    #end

Users who may need to render to a non-square pixel format should indeed
opt for a fixed aspect ratio, and use a variation of the above test to
warn rather than abort:

    camera {
      right x*4/3
    }
    #if (image_width/image_height != 4/3)
      #warning "Scene is designed for 4:3 aspect ratio!\n"
      #warning "Rendering for non-square pixels.\n"
    #end


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