clipka <ano### [at] anonymousorg> wrote:
> Am 12.10.2017 um 08:36 schrieb And:
> > clipka <ano### [at] anonymousorg> wrote:
> >> Am 11.10.2017 um 16:35 schrieb And:
> >>
> >>>>> So I see that it states an "inside_vector <0,0,1> "(from poseray) in the last
> >>>>> item in each mesh2 object. It does not contain sufficient information.
> >>>>
> >>>> With that statement, the mesh should work fine in CSG difference (or
> >>>> intersection or union, for that matter).
> >>>>
> >>>> Not sure what you mean by "it does not contain sufficient information".
> >>>
> >>> Because there is just one vector <0,0,1> at the end, I suppose that it should
> >>> be a lot of vectors. Maybe each face have one vector, and should vary from face
> >>> to face, I don't know。。。 I suppose it should look like
> >>> that.
> >>
> >> No; there is only one `inside_vector` per mesh; it tells POV-Ray that in
> >> order to test whether a given point is inside the mesh or not, it should
> >> shoot a ray in the direction specified by that parameter, and count the
> >> number of surfaces encountered in that direction. If the count is odd,
> >> the point must be inside the mesh; if the count is even, the point must
> >> be outside.
> >
> > Well, that it seems poseray adds a symbolic vector, because <0,0,1> does not
> > inside my model in fact. And it shouldn't get such an information because the
> > mesh was output from sketchup it does not contain that, moreover most of the
> > mesh 3d model does not have a well construct that contain a inside/ outside
> > distinction.
>
> As described above, `inside_vector` does not specify a location, but
> rather a direction (in this case parallel to the z axis).
>
> The "given point" mentioned above will arise from the rendering
> algorithm, more specifically the algorithm used to render CSG
> differences, intersections or merges. As part of this algorithm, POV-Ray
> frequently needs to answer the question, "this point I've found on the
> surface of object A, is it inside or outside object B?"
>
> The procedure I described earlier, which makes use of `inside_vector` as
> a direction, is how POV-Ray tries to answers this question for cases
> where object B is a mesh (or mesh2).

Hmm...it seems ok, if mesh shape is closed. But just like Alain said, need to
slightly change it.

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