Am 09.05.2016 um 07:48 schrieb Le_Forgeron:
> Le 09/05/2016 à 02:43, clipka a écrit :
> 
>  and am wondering what the uv_mapping
>> rules might be (I think, ideally they should match those of the "cone"
>> primitive).
>>
> 
> Ah, Ah... very funny. ROTFL and far more. Really the best joke ever.

I concede I didn't have a closer look at the cone implementation; just
intended to make sure as early as possible in the design process that
the UV mapping isn't inconsistent with stuff we already have.

Obviously, yeah, since we don't seem to have UV mapping for the cone in
the first place, that turned out to be a moot point.

Please don't just grab something randomly out of a bag though. What I
see in your sample image looks like a ratio of 1:3:1 for the three
components of the object; since this is arbitrary anyway, I would
suggest a ratio of 1:2:1 instead. Not only does this slightly simplify
the maths the user will have to do, and also makes those operations
mathematically more stable (a floating-point division by any power of 2
is lossless; a divison by 5 never is) -- much more importantly, it is a
far better fit for standard image sizes commonly used for UV mapping
(which tend to be powers of 2; even where image sizes are multiples of
5, they'll typically also be multiples of 4.)

We should also consider whether we want the UV mapping of the main body
to just use a cylindrical mapping (as seems to be the case in your
sample image, though that might of course be an optical illusion), or
whether we want the mapping to be equidistant along what I presume to be
the V coordinate (essentially boiling down to a variation of toroidal
mapping).

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