Merge branch 'force-charge-distance' into 3.4

d3.js

@@ -6112,19 +6112,21 @@
     return chord;
   };
   d3.layout.force = function() {
-    var force = {}, event = d3.dispatch("start", "tick", "end"), size = [ 1, 1 ], drag, alpha, friction = .9, linkDistance = d3_layout_forceLinkDistance, linkStrength = d3_layout_forceLinkStrength, charge = -30, gravity = .1, theta = .8, nodes = [], links = [], distances, strengths, charges;
+    var force = {}, event = d3.dispatch("start", "tick", "end"), size = [ 1, 1 ], drag, alpha, friction = .9, linkDistance = d3_layout_forceLinkDistance, linkStrength = d3_layout_forceLinkStrength, charge = -30, chargeDistance2 = d3_layout_forceChargeDistance2, gravity = .1, theta2 = .64, nodes = [], links = [], distances, strengths, charges;
     function repulse(node) {
       return function(quad, x1, _, x2) {
         if (quad.point !== node) {
-          var dx = quad.cx - node.x, dy = quad.cy - node.y, dn = 1 / Math.sqrt(dx * dx + dy * dy);
-          if ((x2 - x1) * dn < theta) {
-            var k = quad.charge * dn * dn;
+          var dx = quad.cx - node.x, dy = quad.cy - node.y, dw = x2 - x1, dn = dx * dx + dy * dy;
+          if (dw * dw / theta2 < dn) {
+            if (dn < chargeDistance2) {
+              var k = quad.charge / dn;
               node.px -= dx * k;
               node.py -= dy * k;
+            }
             return true;
           }
-          if (quad.point && isFinite(dn)) {
-            var k = quad.pointCharge * dn * dn;
+          if (quad.point && dn && dn < chargeDistance2) {
+            var k = quad.pointCharge / dn;
             node.px -= dx * k;
             node.py -= dy * k;
           }
@@ -6228,14 +6230,19 @@
       charge = typeof x === "function" ? x : +x;
       return force;
     };
+    force.chargeDistance = function(x) {
+      if (!arguments.length) return Math.sqrt(chargeDistance2);
+      chargeDistance2 = x * x;
+      return force;
+    };
     force.gravity = function(x) {
       if (!arguments.length) return gravity;
       gravity = +x;
       return force;
     };
     force.theta = function(x) {
-      if (!arguments.length) return theta;
-      theta = +x;
+      if (!arguments.length) return Math.sqrt(theta2);
+      theta2 = x * x;
       return force;
     };
     force.alpha = function(x) {
@@ -6353,7 +6360,7 @@
     quad.cx = cx / quad.charge;
     quad.cy = cy / quad.charge;
   }
-  var d3_layout_forceLinkDistance = 20, d3_layout_forceLinkStrength = 1;
+  var d3_layout_forceLinkDistance = 20, d3_layout_forceLinkStrength = 1, d3_layout_forceChargeDistance2 = Infinity;
   d3.layout.hierarchy = function() {
     var sort = d3_layout_hierarchySort, children = d3_layout_hierarchyChildren, value = d3_layout_hierarchyValue;
     function recurse(node, depth, nodes) {

src/layout/force.js

@@ -18,8 +18,9 @@ d3.layout.force = function() {
       linkDistance = d3_layout_forceLinkDistance,
       linkStrength = d3_layout_forceLinkStrength,
       charge = -30,
+      chargeDistance2 = d3_layout_forceChargeDistance2,
       gravity = .1,
-      theta = .8,
+      theta2 = .64,
       nodes = [],
       links = [],
       distances,
@@ -31,18 +32,21 @@ d3.layout.force = function() {
       if (quad.point !== node) {
         var dx = quad.cx - node.x,
             dy = quad.cy - node.y,
-            dn = 1 / Math.sqrt(dx * dx + dy * dy);
+            dw = x2 - x1,
+            dn = dx * dx + dy * dy;
 
         /* Barnes-Hut criterion. */
-        if ((x2 - x1) * dn < theta) {
-          var k = quad.charge * dn * dn;
+        if (dw * dw / theta2 < dn) {
+          if (dn < chargeDistance2) {
+            var k = quad.charge / dn;
             node.px -= dx * k;
             node.py -= dy * k;
+          }
           return true;
         }
 
-        if (quad.point && isFinite(dn)) {
-          var k = quad.pointCharge * dn * dn;
+        if (quad.point && dn && dn < chargeDistance2) {
+          var k = quad.pointCharge / dn;
           node.px -= dx * k;
           node.py -= dy * k;
         }
@@ -169,6 +173,12 @@ d3.layout.force = function() {
     return force;
   };
 
+  force.chargeDistance = function(x) {
+    if (!arguments.length) return Math.sqrt(chargeDistance2);
+    chargeDistance2 = x * x;
+    return force;
+  };
+
   force.gravity = function(x) {
     if (!arguments.length) return gravity;
     gravity = +x;
@@ -176,8 +186,8 @@ d3.layout.force = function() {
   };
 
   force.theta = function(x) {
-    if (!arguments.length) return theta;
-    theta = +x;
+    if (!arguments.length) return Math.sqrt(theta2);
+    theta2 = x * x;
     return force;
   };
 
@@ -352,4 +362,5 @@ function d3_layout_forceAccumulate(quad, alpha, charges) {
 }
 
 var d3_layout_forceLinkDistance = 20,
-    d3_layout_forceLinkStrength = 1;
+    d3_layout_forceLinkStrength = 1,
+    d3_layout_forceChargeDistance2 = Infinity;