Le 26/10/2016 à 17:55, Le_Forgeron a écrit :
> Le 26/10/2016 à 01:20, clipka a écrit :
>> Am 25.10.2016 um 18:55 schrieb Le_Forgeron:
>>
>>> You should also have a look at box uv_mapping... it's strange too.
>>>
>>> You can read it from the inside.
>>
>> Caution: The question whether you can read text from the outside or
>> inside depends not only on the UV mapping scheme, but also on the
>> handedness of the coordinate system.
>>
> 
> Oh, another parameter in the equation then. Are you sure of that ?
> 
> All work and no play makes jack...
> 

Ok, current state of hgpovray:
(did I forget any object ?)

left handed
===========
bicubic_patch
lathe bezier (start +x, go +z)
lathe cubic (start +x, go +z)
lathe linear (start +x, go +z)
lathe quadratic (start +x, go +z)
sor (start +x, go +z)
sphere (start +x, go +z)
sphere_sweep (b )
sphere_sweep (cubic)
sphere_sweep (linear)

right handed
============
box (wrapping)
cone (start +x, go +y)

problem
=======
cylinder (right handed, start +x, go -y)
lemon (right handed, start +x, go -y)
ovus (right handed, start +x, go +z, bottom ?)
torus (right handed, start -x, go +z)

strange (interior/exterior)
===========================
parametric (left handed, strange)
prism bezier (strange)
prism cubic (strange)
prism linear (strange)
prism quadratic (strange)
mesh (strange)

not mapped, but no problem
==========================
blob
disc
isosurface
julia_fractal
plane
polygon
polynomial
smooth_triangle
superellipsoid
text
triangle
height_field


The historical uv-mapping of the torus is not similar to the sphere, in
regard to the starting axis and handness.

The sphere_sweep is extending the u axis along the sweep, similar to the
torus along the major circle, so should be kept.

the bottom face of prism is not the correct texture for interior vs
exterior (compared to similar topological object like sphere)
(And hg-povray already got a correction for text object on that)

The mesh & parametric are screwed:
* cannot be predicted for interior vs exterior
* parametric with a continuous surface changes interior & exterior in middle
* parametric are not reporting all intersections and hole appears when
clipped or intersected

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