flow like the river

BACK_BACK/node_modules/d3-ease/src/circle.js

@@ -0,0 +1,11 @@
+export function circleIn(t) {
+  return 1 - Math.sqrt(1 - t * t);
+}
+
+export function circleOut(t) {
+  return Math.sqrt(1 - --t * t);
+}
+
+export function circleInOut(t) {
+  return ((t *= 2) <= 1 ? 1 - Math.sqrt(1 - t * t) : Math.sqrt(1 - (t -= 2) * t) + 1) / 2;
+}