in the beginning

arbor_src/physics/worker.js

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+//
+// worker.js
+//
+// wraps physics.js in an onMessage/postMessage protocol that the
+// Kernel object can deal with
+//
+importScripts('atoms.js');
+importScripts('barnes-hut.js');  
+importScripts('physics.js');  
+// alias over the missing jquery utils so we can run in a worker
+$ = {
+  each:function(obj, callback){
+    if ($.isArray(obj)){
+      for (var i=0, j=obj.length; i<j; i++) callback(i, obj[i])
+    }else{
+      for (var k in obj) callback(k, obj[k])
+    }
+  },
+  map:function(arr, fn){
+    var out = []
+    $.each(arr, function(i, elt){
+      var result = fn(elt, i)
+      if (result!==undefined) out.push(result)
+    })
+    return out
+  },
+
+  isArray:function(obj){
+    return (obj.constructor.toString().indexOf("Array") != -1)
+  },
+
+  inArray:function(elt, arr){
+    for (var i=0, j=arr.length; i<j; i++) if (arr[i]===elt) return i;
+    return -1
+  }    
+}
+// endalias
+var PhysicsWorker = function(){
+  var _timeout = 20
+  var _physics = null
+  var _physicsInterval = null
+  var _lastTick = null
+  
+  var times = []
+  var last = new Date().valueOf()
+  
+  var that = {  
+    init:function(param){
+      that.timeout(param.timeout)
+      _physics = Physics(param.dt, param.stiffness, param.repulsion, param.friction, that.tock)
+      return that
+    },
+    timeout:function(newTimeout){
+      if (newTimeout!=_timeout){
+        _timeout = newTimeout
+        if (_physicsInterval!==null){
+          that.stop()
+          that.go()
+        }
+      }
+    },
+    go:function(){
+      if (_physicsInterval!==null) return
+
+      // postMessage('starting')
+      _lastTick=null
+      _physicsInterval = setInterval(that.tick, _timeout)
+    },
+    stop:function(){
+      if (_physicsInterval===null) return
+      clearInterval(_physicsInterval);
+      _physicsInterval = null;
+      // postMessage('stopping')
+    },
+    tick:function(){
+      // iterate the system
+      _physics.tick()    
+
+
+      // but stop the simulation when energy of the system goes below a threshold
+      var sysEnergy = _physics.systemEnergy()
+      if ((sysEnergy.mean + sysEnergy.max)/2 < 0.05){
+        if (_lastTick===null) _lastTick=new Date().valueOf()
+        if (new Date().valueOf()-_lastTick>1000){
+          that.stop()
+        }else{
+          // postMessage('pausing')
+        }
+      }else{
+        _lastTick = null
+      }
+      
+    },
+
+    tock:function(sysData){
+      sysData.type = "geometry"
+      postMessage(sysData)
+    },
+    
+    modifyNode:function(id, mods){
+      _physics.modifyNode(id, mods)  
+      that.go()
+    },
+
+    modifyPhysics:function(param){
+      _physics.modifyPhysics(param)
+    },
+    
+    update:function(changes){
+      var epoch = _physics._update(changes)
+    }
+  }
+  
+  return that
+}
+
+
+var physics = PhysicsWorker()
+
+onmessage = function(e){
+  if (!e.data.type){
+    postMessage("¿kérnèl?")
+    return
+  }
+  
+  if (e.data.type=='physics'){
+    var param = e.data.physics
+    physics.init(e.data.physics)
+    return
+  }
+  
+  switch(e.data.type){
+    case "modify":
+      physics.modifyNode(e.data.id, e.data.mods)
+      break
+
+    case "changes":
+      physics.update(e.data.changes)
+      physics.go()
+      break
+      
+    case "start":
+      physics.go()
+      break
+      
+    case "stop":
+      physics.stop()
+      break
+      
+    case "sys":
+      var param = e.data.param || {}
+      if (!isNaN(param.timeout)) physics.timeout(param.timeout)
+      physics.modifyPhysics(param)
+      physics.go()
+      break
+    }  
+}