Le 31/10/2016 à 15:25, William F Pokorny a écrit :
> Lines up reasonably well with where I think hgpovray is. A few
> questions/comments:
> 
> - I'm assuming your information is relative to only the uv_mapping
> mechanism?

Yes

> 
> - Is the cone and cylindrical behavior really different as you show? The
> underlying code for the cone, cylinder & uv_mapping is identical, right?
> 

They share the same base, but a true cone is not a cylinder

> - Many objects are listed as not mapped, but I think when we use
> uv_mapping with those we'll get a default planar mapping.
> 

it's not really a mapping


> - To keep track, the odd prism behavior has a github issue open against
> it in #65.

Nice.


> - I thought you added normal determination and mapping to your new
> hgpovray nurbs surface. If I'm remembering this correctly, did you not
> list it because it is an hgpovray only feature?

Oh, right, I forgot the rational_bezier_patch, which is a viewable object.
Nurbs, on the other hand, is like spline: an abstraction which must be
sampled as mesh to be viewed.


> 
> -----------
> 
> As for the right vs left handed systems part of the review and
> discussion I want to start with the disclaimer I'm far from experienced
> with moving scenes / models between the two conventions. In fact, I
> don't myself do much uv_mapping.
> 
> That said, my first reaction to our mapping flipping around in left vs
> right conventions is - of course it does. Further, given POV-Ray's
> ability to flip up, right and direction in the camera, we can scramble
> mappings (and more) working entirely within any left or right handed
> coordinate system with respect to any particular scene view.
> 
> Add user_defined cameras and the new hgpovray arrayed multiple cameras,
> where any handedness is by ray at best, not determinable at all in the
> worst case, and I'm more than a little fuzzy on what kinds of map
> improvements with respect to handedness we are chasing?

I would go for uniformity. But that is doomed, from box :-)

I'm going to change cylinder, cone, ovus and lemon to join the sphere
(left handed for text reading...),
and I wonder if the torus should be "corrected" or remain a curiosity
like box.


> 
> Are we thinking perhaps about additional parameters to "uv_mapping" et
> al to help with the mapping element of moving from one handed convention
> to another? Are we thinking of other features or are we just trying to
> get to where POV-Ray and its derivatives are consistent?
> 

I won't add any parameter nor options.
you can always transform the texture afterwards. (scale <-1,1,1> and
friends)

> Thanks for your time.
> 
> Bill P.

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