Thomas de Groot nous apporta ses lumieres en ce 14-12-2006 04:03:
> "Warp" <war### [at] tagpovrayorg> schreef in bericht 
> news:458072c4@news.povray.org...
>> Thomas de Groot <t.d### [at] internldotnet> wrote:
>>>>  Does trace() always return a normalized vector?
>>> Yes, if you define also the fourth trace parameter (a vector), Norm in 
>>> this
>>> case (see documentation 3.2.1.4.5).
>>  There's no such section number in the current documentation
>> (http://povray.org/documentation/view/3.6.1/570/)

>>  As for the documentation on the trace() function (2.2.1.4.5), it does not
>> mention returning a normalized vector.


> Strange....
> My documentation for version 3.6 is headed:   3.2.1.4.5  Functions
> This is what it says about trace():
> quote
> trace(OBJECT_IDENTIFIER, A, B, [VECTOR_IDENTIFIER]). trace helps you finding 
> the exact location of a ray intersecting with an object's surface. It traces 
> a ray beginning at the point A in the direction specified by the vector B. 
> If the ray hits the specified object, this function returns the coordinate 
> where the ray intersected the object. If not, it returns <0,0,0>. If a 
> fourth parameter in the form of a vector identifier is provided, the normal 
> of the object at the intersection point (not including any normal 
> perturbations due to textures) is stored into that vector. If no 
> intersection was found, the normal vector is reset to <0,0,0>.
> Note: Checking the normal vector for <0,0,0> is the only reliable way to 
> determine whether an intersection has actually occurred, intersections can 
> and do occur anywhere, including at <0,0,0>.

> unquote

> so.... what do you think?

> Thomas




There is no mention of a normalised normal vector, it mention the normal vector.

-- 
Alain
-------------------------------------------------
A day for firm decisions!!!!!  Or is it?

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