Merged.

app/assets/javascripts/workers/worker_world.js

@@ -268,6 +268,7 @@ self.setupDebugWorldToRunUntilFrame = function (args) {
     if (!self.debugWorld || userCodeMapHasChanged || args.frame < self.currentDebugWorldFrame) {
         try {
             self.debugWorld = new World(args.userCodeMap);
+            self.debugWorld.levelSessionIDs = args.levelSessionIDs;
             if (args.level)
                 self.debugWorld.loadFromLevel(args.level, true);
             self.debugWorld.debugging = true;
@@ -320,6 +321,7 @@ self.runWorld = function runWorld(args) {
 
   try {
     self.world = new World(args.userCodeMap);
+    self.world.levelSessionIDs = args.levelSessionIDs;
     if(args.level)
       self.world.loadFromLevel(args.level, true);
     self.world.preloading = args.preload;

app/lib/God.coffee

@@ -46,6 +46,7 @@ module.exports = class God extends CocoClass
     super()
 
   setLevel: (@level) ->
+  setLevelSessionIDs: (@levelSessionIDs) ->
   setGoalManager: (goalManager) -> @angelsShare.goalManager = goalManager
   setWorldClassMap: (worldClassMap) -> @angelsShare.worldClassMap = worldClassMap
 
@@ -73,6 +74,7 @@ module.exports = class God extends CocoClass
     @angelsShare.workQueue.push
       userCodeMap: userCodeMap
       level: @level
+      levelSessionIDs: @levelSessionIDs
       goals: @angelsShare.goalManager?.getGoals()
       headless: @angelsShare.headless
       preload: preload
@@ -99,6 +101,7 @@ module.exports = class God extends CocoClass
       args:
         userCodeMap: @currentUserCodeMap
         level: @level
+        levelSessionIDs: @levelSessionIDs
         goals: @goalManager?.getGoals()
         frame: args.frame
         currentThangID: args.thangID

app/lib/LevelLoader.coffee

@@ -239,6 +239,7 @@ module.exports = class LevelLoader extends CocoClass
     return if @initialized
     @initialized = true
     @world = new World()
+    @world.levelSessionIDs = if @opponentSessionID then [@sessionID, @opponentSessionID] else [@sessionID]
     serializedLevel = @level.serialize(@supermodel)
     @world.loadFromLevel serializedLevel, false
     console.log "World has been initialized from level loader."

app/lib/simulator/Simulator.coffee

@@ -103,6 +103,7 @@ module.exports = class Simulator extends CocoClass
 
   setupGod: ->
     @god.setLevel @level.serialize @supermodel
+    @god.setLevelSessionIDs (session.id for session in @task.getSessions())
     @god.setWorldClassMap @world.classMap
     @god.setGoalManager new GoalManager(@world, @level.get 'goals')
 

app/lib/world/rand.coffee

@@ -1,8 +1,7 @@
-# If we ever need a seedable PRNG, we can use this.
 # http://coffeescriptcookbook.com/chapters/math/generating-predictable-random-numbers
 class Rand
   @className: "Rand"
-  # if created without a seed, uses current time as seed
+  # If created without a seed, uses current time as seed.
   constructor: (@seed) ->
     # Knuth and Lewis' improvements to Park and Miller's LCPRNG
     @multiplier = 1664525
@@ -11,9 +10,9 @@ class Rand
     unless @seed? and 0 <= seed < @modulo
       @seed = (new Date().valueOf() * new Date().getMilliseconds()) % @modulo
 
-  # sets new seed value
+  # sets new seed value, even handling negative numbers
-  seed: (seed) ->
+  setSeed: (seed) ->
-    @seed = seed
+    @seed = ((seed % @modulo) + @modulo) % @modulo
 
   # return a random integer 0 <= n < @modulo
   randn: =>
@@ -32,4 +31,4 @@ class Rand
   rand2: (min, max) =>
     min + @rand max - min
 
-module.exports = Rand
+module.exports = Rand

app/lib/world/world.coffee

@@ -30,7 +30,7 @@ module.exports = class World
     @systems = []
     @systemMap = {}
     @scriptNotes = []
-    @rand = new Rand 0
+    @rand = new Rand 0  # Existence System may change this seed
     @frames = [new WorldFrame(@, 0)]
 
   getFrame: (frameIndex) ->
@@ -405,7 +405,7 @@ module.exports = class World
         return
     @finishDeserializing w, finishedWorldCallback, perf
 
-  @finishDeserializing: (w, finishedWorldCallback, perf) =>
+  @finishDeserializing: (w, finishedWorldCallback, perf) ->
     perf.t4 = now()
     w.ended = true
     w.getFrame(w.totalFrames - 1).restoreState()

app/views/play/level_view.coffee

@@ -100,9 +100,10 @@ module.exports = class PlayLevelView extends View
     @supermodel.models = givenSupermodel.models
     @supermodel.collections = givenSupermodel.collections
     @supermodel.shouldSaveBackups = givenSupermodel.shouldSaveBackups
-    @god?.level = @level.serialize @supermodel
+
+    serializedLevel = @level.serialize @supermodel
+    @god?.setLevel serializedLevel
     if @world
-      serializedLevel = @level.serialize(@supermodel)
       @world.loadFromLevel serializedLevel, false
     else
       @load()
@@ -149,6 +150,7 @@ module.exports = class PlayLevelView extends View
     team = @getQueryVariable("team") ? @world.teamForPlayer(0)
     @loadOpponentTeam(team)
     @god.setLevel @level.serialize @supermodel
+    @god.setLevelSessionIDs if @otherSession then [@session.id, @otherSession.id] else [@session.id]
     @god.setWorldClassMap @world.classMap
     @setTeam team
     @initGoalManager()

app/views/play/spectate_view.coffee

@@ -90,9 +90,9 @@ module.exports = class SpectateLevelView extends View
     application.router.navigate "/play?not_found=#{@levelID}", {trigger: true}
 
   setLevel: (@level, @supermodel) ->
-    @god?.level = @level.serialize @supermodel
+    serializedLevel = @level.serialize @supermodel
+    @god?.setLevel serializedLevel
     if @world
-      serializedLevel = @level.serialize(@supermodel)
       @world.loadFromLevel serializedLevel, false
     else
       @load()
@@ -156,6 +156,7 @@ module.exports = class SpectateLevelView extends View
     team = @world.teamForPlayer(0)
     @loadOpponentTeam(team)
     @god.setLevel @level.serialize @supermodel
+    @god.setLevelSessionIDs if @otherSession then [@session.id, @otherSession.id] else [@session.id]
     @god.setWorldClassMap @world.classMap
     @setTeam team
     @initSurface()

headless_client/worker_world.coffee

@@ -78,6 +78,7 @@ work = () ->
 
     try
       self.world = new World(args.userCodeMap)
+      self.world.levelSessionIDs = args.levelSessionIDs
       self.world.loadFromLevel args.level, true  if args.level
       self.world.headless = args.headless
       self.goalManager = new GoalManager(self.world)