动态改变Javascript D3布局模拟

Dynamically changing the Javascript D3 layout simulation

本文关键字：布局 模拟 D3 Javascript 改变 动态      更新时间：2023-09-26

我试图在https://github.com/mbostock/d3/blob/master/examples/force/force-multi-foci.html的D3示例中动态改变模拟细节。我放入一个复选框，然后动态地分配tick处理程序，如下所示(完整代码见http://pastebin.com/k4P0uzHK):

$("#chkBox").change(function(){
  if ($(this).is(':checked')) {
    force.on("tick", forceTick);
  } else {
    force.on("tick", forceTick2);
  }
});
forceTick = function(e) {
  // Push different nodes in different directions for clustering.
  var ky = 400 * e.alpha;
  var kx = 20 * e.alpha;
  hLinks.forEach(function(hlink) {
    var yB = hlink.source.y, yT = hlink.target.y;
    if (yB<(yT+20)) { hlink.source.y += Math.min(ky,yT+20-yB); hlink.target.y -= Math.min(ky,yT+20-yB);}
    var xB = hlink.source.x, xT = hlink.target.x;
    if (xB<(xT-20)) { hlink.source.x += Math.min(kx,xT-20-xB); hlink.target.x -= Math.min(kx,xT-20-xB);}
    if (xB>(xT+20)) { hlink.source.x -= Math.min(kx,xB-xT-20); hlink.target.x += Math.min(kx,xB-xT-20);}
  });
  node.attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; });
  link.attr("x1", function(d) { return d.source.x; })
       .attr("y1", function(d) { return d.source.y; })
       .attr("x2", function(d) { return d.target.x; })
       .attr("y2", function(d) { return d.target.y; });
};

forceTick2 = function(e) {
  node.attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; });
  link.attr("x1", function(d) { return d.source.x; })
       .attr("y1", function(d) { return d.source.y; })
       .attr("x2", function(d) { return d.target.x; })
       .attr("y2", function(d) { return d.target.y; });
};

但实际上似乎只有先给出的处理程序才有效。是否存在动态控制模拟的方法?

用于部队布局的on操作符(以及使用d3.dispatch的任何其他操作符)添加了一个事件侦听器。它不会替换现有的事件侦听器。强制布局目前没有公开删除或替换现有事件侦听器的机制。

这是一个bug。我打算使布局的on操作符与选择一致，这允许您通过多次调用on来添加，替换和删除事件侦听器。如果使用名称空间(如"tick")，仍然可以注册多个侦听器。Foo "answers"tick.bar")

与此同时，简单的修复方法是使用单个方法作为tick监听器，但随后使用一些全局布尔值来确定每个tick要采用哪两种行为。在您的例子中，像这样: 
if (checked) {
  … clustering …
}
… update link positions …
… update node positions …

另外，这消除了代码重复。:)

你可以在d3.v4中看到一个很好的例子:https://bl.ocks.org/steveharoz/8c3e2524079a8c440df60c1ab72b5d03

您可以在这里看到重要的功能:

// add forces to the simulation
function initializeForces() {
  // add forces and associate each with a name
  simulation
    .force("link", d3.forceLink())
    .force("charge", d3.forceManyBody())
    .force("collide", d3.forceCollide())
    .force("center", d3.forceCenter())
    .force("forceX", d3.forceX())
    .force("forceY", d3.forceY());
  // apply properties to each of the forces
  updateForces();
}
// apply new force properties
function updateForces() {
  // get each force by name and update the properties
  simulation.force("center")
    .x(width * forceProperties.center.x)
    .y(height * forceProperties.center.y);
  simulation.force("charge")
    .strength(forceProperties.charge.strength * forceProperties.charge.enabled)
    .distanceMin(forceProperties.charge.distanceMin)
    .distanceMax(forceProperties.charge.distanceMax);
  simulation.force("collide")
    .strength(forceProperties.collide.strength * forceProperties.collide.enabled)
    .radius(forceProperties.collide.radius)
    .iterations(forceProperties.collide.iterations);
  simulation.force("forceX")
    .strength(forceProperties.forceX.strength * forceProperties.forceX.enabled)
    .x(width * forceProperties.forceX.x);
  simulation.force("forceY")
    .strength(forceProperties.forceY.strength * forceProperties.forceY.enabled)
    .y(height * forceProperties.forceY.y);
  simulation.force("link")
    .id(function(d) {return d.id;})
    .distance(forceProperties.link.distance)
    .iterations(forceProperties.link.iterations)
    .links(forceProperties.link.enabled ? graph.links : []);
  // updates ignored until this is run
  // restarts the simulation (important if simulation has already slowed down)
  simulation.alpha(1).restart();
}
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