Fix vertex order in prim_tetrahedron

[rkharsan]

Currently, 2 of the faces returned by primitive.prim_tetrahedron() have the vertices in incorrect order. This leads to incorrect normals being calculated, and the two faces in question appear invisible from the outside.

Current version: Note the missing faces!

Fixed version: All faces are now visible from the outside.

Minimal reproducible example:

from fury import utils, window, primitive

v, f = primitive.prim_tetrahedron()

# Uncomment to see the fix
# f[1][1], f[1][2] = f[1][2], f[1][1]
# f[3][1], f[3][2] = f[3][2], f[3][1]

a = utils.get_actor_from_primitive(v, f)

scene = window.Scene()
scene.add(a)
window.show(scene)

[codecov]

Codecov Report

Merging #571 (77f18ee) into master (f1ee5f8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #571   +/-   ##
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  Coverage   88.55%   88.55%           
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  Files          55       55           
  Lines       10979    10979           
  Branches     1083     1083           
=======================================
  Hits         9723     9723           
  Misses        959      959           
  Partials      297      297           

[skoudoro]

Thank you and good catch @rkharsan,

That is strange... I wonder when we introduce this issue and we did not see it.

Anyway, thanks and merging