Add simulation.randomSource.

src/collide.js

@@ -13,6 +13,7 @@ function y(d) {
 export default function(radius) {
   var nodes,
       radii,
+      random,
       strength = 1,
       iterations = 1;
 
@@ -46,8 +47,8 @@ export default function(radius) {
               y = yi - data.y - data.vy,
               l = x * x + y * y;
           if (l < r * r) {
-            if (x === 0) x = jiggle(), l += x * x;
-            if (y === 0) y = jiggle(), l += y * y;
+            if (x === 0) x = jiggle(random), l += x * x;
+            if (y === 0) y = jiggle(random), l += y * y;
             l = (r - (l = Math.sqrt(l))) / l * strength;
             node.vx += (x *= l) * (r = (rj *= rj) / (ri2 + rj));
             node.vy += (y *= l) * r;
@@ -77,8 +78,9 @@ export default function(radius) {
     for (i = 0; i < n; ++i) node = nodes[i], radii[node.index] = +radius(node, i, nodes);
   }
 
-  force.initialize = function(_) {
-    nodes = _;
+  force.initialize = function(_nodes, _random) {
+    nodes = _nodes;
+    random = _random;
     initialize();
   };
 

src/jiggle.js

@@ -1,3 +1,3 @@
-export default function() {
-  return (Math.random() - 0.5) * 1e-6;
+export default function(random) {
+  return (random() - 0.5) * 1e-6;
 }

src/link.js

@@ -20,6 +20,7 @@ export default function(links) {
       nodes,
       count,
       bias,
+      random,
       iterations = 1;
 
   if (links == null) links = [];
@@ -32,8 +33,8 @@ export default function(links) {
     for (var k = 0, n = links.length; k < iterations; ++k) {
       for (var i = 0, link, source, target, x, y, l, b; i < n; ++i) {
         link = links[i], source = link.source, target = link.target;
-        x = target.x + target.vx - source.x - source.vx || jiggle();
-        y = target.y + target.vy - source.y - source.vy || jiggle();
+        x = target.x + target.vx - source.x - source.vx || jiggle(random);
+        y = target.y + target.vy - source.y - source.vy || jiggle(random);
         l = Math.sqrt(x * x + y * y);
         l = (l - distances[i]) / l * alpha * strengths[i];
         x *= l, y *= l;
@@ -86,8 +87,9 @@ export default function(links) {
     }
   }
 
-  force.initialize = function(_) {
-    nodes = _;
+  force.initialize = function(_nodes, _random) {
+    nodes = _nodes;
+    random = _random;
     initialize();
   };
 

src/manyBody.js

@@ -6,6 +6,7 @@ import {x, y} from "./simulation.js";
 export default function() {
   var nodes,
       node,
+      random,
       alpha,
       strength = constant(-30),
       strengths,
@@ -63,8 +64,8 @@ export default function() {
     // Limit forces for very close nodes; randomize direction if coincident.
     if (w * w / theta2 < l) {
       if (l < distanceMax2) {
-        if (x === 0) x = jiggle(), l += x * x;
-        if (y === 0) y = jiggle(), l += y * y;
+        if (x === 0) x = jiggle(random), l += x * x;
+        if (y === 0) y = jiggle(random), l += y * y;
         if (l < distanceMin2) l = Math.sqrt(distanceMin2 * l);
         node.vx += x * quad.value * alpha / l;
         node.vy += y * quad.value * alpha / l;
@@ -77,8 +78,8 @@ export default function() {
 
     // Limit forces for very close nodes; randomize direction if coincident.
     if (quad.data !== node || quad.next) {
-      if (x === 0) x = jiggle(), l += x * x;
-      if (y === 0) y = jiggle(), l += y * y;
+      if (x === 0) x = jiggle(random), l += x * x;
+      if (y === 0) y = jiggle(random), l += y * y;
       if (l < distanceMin2) l = Math.sqrt(distanceMin2 * l);
     }
 
@@ -89,8 +90,9 @@ export default function() {
     } while (quad = quad.next);
   }
 
-  force.initialize = function(_) {
-    nodes = _;
+  force.initialize = function(_nodes, _random) {
+    nodes = _nodes;
+    random = _random;
     initialize();
   };
 

src/simulation.js

@@ -21,7 +21,8 @@ export default function(nodes) {
       velocityDecay = 0.6,
       forces = new Map(),
       stepper = timer(step),
-      event = dispatch("tick", "end");
+      event = dispatch("tick", "end"),
+      random = Math.random;
 
   if (nodes == null) nodes = [];
 
@@ -75,7 +76,7 @@ export default function(nodes) {
   }
 
   function initializeForce(force) {
-    if (force.initialize) force.initialize(nodes);
+    if (force.initialize) force.initialize(nodes, random);
     return force;
   }
 
@@ -116,6 +117,10 @@ export default function(nodes) {
       return arguments.length ? (velocityDecay = 1 - _, simulation) : 1 - velocityDecay;
     },
 
+    randomSource: function(_) {
+      return arguments.length ? (random = _, simulation) : random;
+    },
+
     force: function(name, _) {
       return arguments.length > 1 ? ((_ == null ? forces.delete(name) : forces.set(name, initializeForce(_))), simulation) : forces.get(name);
     },