> just check the spec.
http://www.opengl.org/documentation/specs/version2.0/glspec20.pdf
pdf page 31 (page labelled 17) : figure 2.4 ‘Note that…’
that example agrees wtih me, eacatly. the ordering of the STRIP is determioned by the first triangle, certainly, so something has to change for alternating triangles. i never said otherwise.
thus,
0 1
/
2 3
is clockwise for all triangles because it is defined by the first (even though the triangle 1, 2, 3 is ccw defined by the order of successive vertices, so SOMETHING has to change–either the test or two vertices), whereas
0 2
/
1 3
is CCW for the entire strip, even though 1, 2, 3 is CW. therefore, that figure in the opengl spec doesn’t contradict my position.
my position, incidentially, is not to disagree with this statement:
> When drawing a triangles strip, every vertex added to the strip … change the triangle orientation.
> Wrong
every vertex added to the strip DOES change the triangle orientation IF you define winding order as the direction of sucessive vertices. so, saying it is wrong IS wrong.
the answer is “yes, that is true: adding successive vertices DOES change the winding order, and if left unchecked, this WOULD create a mess. BUT: opengl defines the winding order on the first triangle (which is true, c.f. fig 2.4) and then either alternates the test on successive vertices, or flips the last two vertices.”
my objection was to asserting something was wrong, when clearly this is not the case. adding vertices DOES change the winding order, but opengl itself CHANGES something to make the test right.