POV-Ray : Newsgroups : povray.documentation.inbuilt : Errors in light attenuation and height field documentation : Re: Errors in light attenuation and height field documentation Server Time
26 Jan 2022 11:31:45 EST (-0500)
  Re: Errors in light attenuation and height field documentation  
From: James Holsenback
Date: 24 Mar 2013 10:25:49
Message: <514f0ced$1@news.povray.org>
On 03/24/2013 02:01 AM, Cousin Ricky wrote:
> I have found a couple of errors in the 3.7 documentation.
>
> At http://wiki.povray.org/content/Reference:Light_Source#Light_Fading in the
> wiki and in section 3.4.4.1.9 of the 3.7 off-line documentation, an example
> function is given to determine the brightness of a light source:
>
>    #declare Intensity_Factor = function (LD,FD,FP) {pow(1+(LD/FD),FP)/2};
>
> This should be:
>
>    #declare Intensity_Factor = function (LD,FD,FP) {(1+pow(LD/FD,FP))/2};

Indeed I added (well ... plagiarized) it from a NG discussion, that I 
couldn't find to check if a mistake was made. I did however find and 
check my own personal notes from when was putting the entry together and 
it appears that I at least got it right. I couldn't comment of the 
correctness of the math. Care to elaborate? Oh ... IIRC Trevor Quayle 
was the author.

> At http://wiki.povray.org/content/Reference:Height_Field in the wiki and in
> section 3.4.5.1.5 of the 3.7 off-line documentation, the syntax statement for a
> height field function reads:
>
>    HF_FUNCTION:
>      function FieldResolution_X, FieldResolution_Y ( UserDefined_Function )
>
> The parentheses should be curly braces:
>
>    HF_FUNCTION:
>      function FieldResolution_X, FieldResolution_Y { UserDefined_Function }

Hmmm ... OK good find, but for some reason your correction looked 
incomplete. RE: from the declarations above shouldn't it be:

HF_FUNCTION:
   function (FieldResolution_X, FieldResolution_Y) { UserDefined_Function }

>
> In addition, the documentation does not explain height field functions.  I'm
> having to figure out how it works by experimentation.
>
> The 3.6 documentation doesn't even describe the syntax of a height field
> function.

Maybe adding a link to http://wiki.povray.org/content/Reference:Function 
or one of it's sub-sections might do the trick ... maybe you have 
another section in mind.


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