From 0334aa5e0051b59ce4050fd306b26119466e2991 Mon Sep 17 00:00:00 2001
From: Peter Wu <peter@lekensteyn.nl>
Date: Wed, 21 May 2014 15:13:16 +0200
Subject: Move scripts to subdir

Our scripts end up in js/, third-party libraries end up in lib/.
---
 js/collision.js | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 js/collision.js

(limited to 'js/collision.js')

diff --git a/js/collision.js b/js/collision.js
new file mode 100644
index 0000000..acaf728
--- /dev/null
+++ b/js/collision.js
@@ -0,0 +1,36 @@
+/* globals d3 */
+'use strict';
+// source: http://mbostock.github.io/d3/talk/20111018/collision.html
+function collisionTick(nodes) {
+    var q = d3.geom.quadtree(nodes),
+        i = 0,
+        n = nodes.length;
+
+    while (++i < n) {
+        q.visit(collide(nodes[i]));
+    }
+}
+
+function collide(node) {
+    var r = node.radius + 16,
+        nx1 = node.x - r,
+        nx2 = node.x + r,
+        ny1 = node.y - r,
+        ny2 = node.y + r;
+    return function(quad, x1, y1, x2, y2) {
+        if (quad.point && (quad.point !== node)) {
+            var x = node.x - quad.point.x,
+                y = node.y - quad.point.y,
+                l = Math.sqrt(x * x + y * y),
+                r = node.radius + quad.point.radius;
+            if (l < r) {
+                l = (l - r) / l * 0.5;
+                node.x -= x *= l;
+                node.y -= y *= l;
+                quad.point.x += x;
+                quad.point.y += y;
+            }
+        }
+        return x1 > nx2 || x2 < nx1 || y1 > ny2 || y2 < ny1;
+    };
+}
-- 
cgit v1.2.1