[gnramires]

Just fixing a mistake: what I described is the window function, not the integrated (in this case, cosine) function that was used in the article. In this case there would still be ripples when applying the shown window function (in cosine integration). I do think ripple-free are probably better functions (or some faster decaying ripples) because of limited floating point precision generating artifacts (which can be seen in the center in the second demo).

Experimentally playing around a little I've found

fcos = cos(x) * sin(0.5 * w)/(0.5 * w) * smoothstep(6.28,0.0,0.38*w)

To be a good compromise between eliminating high frequency ripple and maintaining good definition.