flow like the river

VISUALIZACION/node_modules/d3-force-3d/src/radial.js

@@ -0,0 +1,67 @@
+import constant from "./constant.js";
+
+export default function(radius, x, y, z) {
+  var nodes,
+      nDim,
+      strength = constant(0.1),
+      strengths,
+      radiuses;
+
+  if (typeof radius !== "function") radius = constant(+radius);
+  if (x == null) x = 0;
+  if (y == null) y = 0;
+  if (z == null) z = 0;
+
+  function force(alpha) {
+    for (var i = 0, n = nodes.length; i < n; ++i) {
+      var node = nodes[i],
+          dx = node.x - x || 1e-6,
+          dy = (node.y || 0) - y || 1e-6,
+          dz = (node.z || 0) - z || 1e-6,
+          r = Math.sqrt(dx * dx + dy * dy + dz * dz),
+          k = (radiuses[i] - r) * strengths[i] * alpha / r;
+      node.vx += dx * k;
+      if (nDim>1) { node.vy += dy * k; }
+      if (nDim>2) { node.vz += dz * k; }
+    }
+  }
+
+  function initialize() {
+    if (!nodes) return;
+    var i, n = nodes.length;
+    strengths = new Array(n);
+    radiuses = new Array(n);
+    for (i = 0; i < n; ++i) {
+      radiuses[i] = +radius(nodes[i], i, nodes);
+      strengths[i] = isNaN(radiuses[i]) ? 0 : +strength(nodes[i], i, nodes);
+    }
+  }
+
+  force.initialize = function(initNodes, ...args) {
+    nodes = initNodes;
+    nDim = args.find(arg => [1, 2, 3].includes(arg)) || 2;
+    initialize();
+  };
+
+  force.strength = function(_) {
+    return arguments.length ? (strength = typeof _ === "function" ? _ : constant(+_), initialize(), force) : strength;
+  };
+
+  force.radius = function(_) {
+    return arguments.length ? (radius = typeof _ === "function" ? _ : constant(+_), initialize(), force) : radius;
+  };
+
+  force.x = function(_) {
+    return arguments.length ? (x = +_, force) : x;
+  };
+
+  force.y = function(_) {
+    return arguments.length ? (y = +_, force) : y;
+  };
+
+  force.z = function(_) {
+    return arguments.length ? (z = +_, force) : z;
+  };
+
+  return force;
+}