In Rhino, to tween means to generate curves that interpolate between given enter curves. The primary look of the phrase shouldn’t be solely clear – it was used not less than way back to in Tolkien, however it’s secure to consider the phrase because the verb type of “between”. In any case, tweening is a really primary operation and elementary a part of the designer’s toolbox. Nonetheless, it will possibly shortly end in curves that intersect one another or self-intersect, even on reasonably complicated enter curves. Normally, crossing tween curves are undesired for aesthetic and sensible causes.
Tweener is a Rhino and Grasshopper plugin that solves this drawback. It strictly ensures absence of crossings and intersections every time the enter curves do not intersect one another. In its easiest use case, the “TweenPlanCurv” Grasshopper part can be utilized immediately as a stand-in substitute for the “TweenCrv” part, and the command “TweenCurves2” can exchange “TweenCurves”. Furthermore, Tweener permits any variety of closed planar enter curves – not simply two, or any two however not essentially closed enter curves on a given floor or brep – not simply in a airplane. Tweener may also generate a whole colour gradient scalar area as an alternative of finitely many curves.
Whereas NURBS curves are outlined by management factors, a Tweener curve is outlined by the form of the area’s boundary curves. Thus, they’re drawn interactively by manipulating their boundary. This gives a special perspective on curve modeling: In actual fact, Tweener comes with an interactive enhancing atmosphere, began with the “TweenerStart” command, that enables the designer to tweak and regulate the customarily very generic look of “power area” curves to present them a extra particular person hand-drawn contact. All Tweener output curves are modeled concurrently and on the identical time, Tweener ensures to keep up the absence of crossings and intersections.
