[Octave-bug-tracker] [bug #65641] 'view' produces incorrect viewpoint when given a vector aligned with the primary axes

[Nicholas Jankowski]

Update of bug #65641 (group octave):

                 Summary: 'view' produces incorrect viewpoint when given a
vector aligned with the X axis => 'view' produces incorrect viewpoint when
given a vector aligned with the primary axes

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Follow-up Comment #24:

the attached patch forces az = +0 when a z-axis vector is specified, and adds
a BIST to check for compatible output.

It's definitely not an elegant fix. I was worried about it being highly
discontinuous for slightly off-z-axis vectors, e.g, [-0.0001, 0, -1], but it
seems matlab is too, and this matches:

matlab:

>> view([-0.0001,0,-1]);[a,b]=view();[a,b,1/a,1/b]
ans =
  -90.0000  -89.9943   -0.0111   -0.0111
>> view([-0.000,0,-1]);[a,b]=view();[a,b,1/a,1/b]
ans =
         0  -90.0000       Inf   -0.0111


patched octave

 view([-0.0001,0,-1]);[a,b]=view();[a,b,1/a,1/b]
ans =

  -9.0000e+01  -8.9994e+01  -1.1111e-02  -1.1112e-02

>>  view([-0.000,0,-1]);[a,b]=view();[a,b,1/a,1/b]
ans =

         0  -90.0000       Inf   -0.0111


i think this would pretty much satisfy the bug report.

(file #55979)

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Additional Item Attachment:

File name: bug65641_zaxisfix.patch        Size: 2KiB
    <https://file.savannah.gnu.org/file/bug65641_zaxisfix.patch?file_id=55979>


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