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-rw-r--r--js/collision.js36
1 files changed, 36 insertions, 0 deletions
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+/* 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;
+ };
+}