Heh - sometimes it takes a relative tome of justification to arrive at a simple explanation!
However the beauty of Bézier curves is that arcs are just a small subset of what they can represent 'well enough'. For moving along an arbitrary (Bézier - you can represent a straight line segment as one trivially) path, what you actually need is first the length of the path (annoyingly not a representable function - iirc) and a parametric form of a Bézier curve (which is how they are best expressed). Then to step along the path at fixed distance at each step you use f(n * fixeddist / length) (here f is the parametric form of the Bézier - returning a 2d point). You'd need some adjustment (+/- 1 pix) to account for rounding error - but I think the idea is sound. Warmest Regards, Mark. Sent from my iPhone On 2 Aug 2017, at 22:18, hh via use-livecode <use-livecode@lists.runrev.com> wrote: >> Mark wrote: >> So, at the level of the graphic object it is a true arc, at the level of >> instructing >> the graphics library it is a Bézier approximation but at the level of >> working out what >> pixels to render it is a polygon. > > Thanks for arriving from your previous post at this very clear statement. > You will have to do a lot of such approximations by simple polygons when you > implement > to move along an SVG path for your SVG widget... ;-) > > p.s. The 360 points of Mark are really good enough for very large circles in > order to > move along such points in 2 seconds. These are 3 points per tick! > _______________________________________________ > use-livecode mailing list > use-livecode@lists.runrev.com > Please visit this url to subscribe, unsubscribe and manage your subscription > preferences: > http://lists.runrev.com/mailman/listinfo/use-livecode _______________________________________________ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
