remove the animation=fade setting, seems we can live without it (for …

…example, setting key: (d,i)=>i would be a way to say that we only want enters and exits?)

src/marks/box.js

@@ -25,7 +25,7 @@ export function boxX(data, {
     ruleY(data, group({x1: loqr1, x2: hiqr2}, {x, y, stroke, strokeOpacity, ...options})),
     barX(data, group({x1: "p25", x2: "p75"}, {x, y, fill, fillOpacity, ...options})),
     tickX(data, group({x: "p50"}, {x, y, stroke, strokeOpacity, strokeWidth, sort, ...options})),
-    dot(data, map({x: oqr}, {x, y, z: y, stroke, strokeOpacity, animation: "fade", ...options}))
+    dot(data, map({x: oqr}, {x, y, z: y, stroke, strokeOpacity, ...options}))
   );
 }
 

src/plot.js

@@ -328,9 +328,9 @@ export function plot(options = {}) {
           const I1 = facet.filter(i => T[i] === time1); // following keyframe
           const K0 = new Set(I0.map(i => K[i]));
           const K1 = new Set(I1.map(i => K[i]));
-          const Kenter = mark.animation === "fade" ? K1 : difference(K1, K0);
-          const Kupdate = mark.animation === "fade" ? new Set([]) : intersection(K0, K1);
-          const Kexit = mark.animation === "fade" ? K0 : difference(K0, K1);
+          const Kenter = difference(K1, K0);
+          const Kupdate = intersection(K0, K1);
+          const Kexit = difference(K0, K1);
           const enter = I1.filter(i => Kenter.has(K[i]));
           const update = I0.filter(i => Kupdate.has(K[i]));
           const target = update.map(i => I1.find(j => K[i] === K[j])); // TODO: use an index