Louis-Francis Ratté-Boulianne authored Sep 30, 2020 and Erik Faye-Lund committed Oct 26, 2020

 Triangle strips are not tesselated the same way in OpenGL and in
 DirectX12. For a triangle strip with vertices: 0, 1, 2, 3, 4...

 DirectX12 will invert the last two vertices of every other triangle
 to preserve the winding order:

 (0, 1, 2) - (1, 3, 2) - (2, 3, 4) - (3, 5, 4)

 Meanwhile, OpenGL expects the first two vertices to be inverted:

 (0, 1, 2) - (2, 1, 3) - (2, 3, 4) - (4, 3, 5)

 This detail is relevent when flat shading or transform feedback
 is enabled. Consequently, we need to re-order vertices in the
 two cases:

  - When flatshading is enabled, attributeAtVertex is not supported, and
    the provoking vertex is the last one OR we are drawing triangle
    strips. (note: line primitives are not implemented yet)

  - When transform feedback is enabled and we are drawing triangle
    strips.