Better algorithm for generating a set of consistent set of random num…

…bers, and fix for SEED_RANDOM()
y-lohse · Sep 11, 2016 · 1998410 · 1998410
1 parent fc3b27f
commit 1998410
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Showing 3 changed files with 16 additions and 11 deletions.
diff --git a/ink-engine-runtime/Story.cs b/ink-engine-runtime/Story.cs
@@ -823,18 +823,19 @@ bool PerformLogicAndFlowControl(Runtime.Object contentObj)
                         Error ("Invalid value for maximum parameter of RANDOM(min, max)");
 
                     // +1 because it's inclusive of min and max, for e.g. RANDOM(1,6) for a dice roll.
-                    //var randomRange = maxInt.value - minInt.value + 1;
-                    if (maxInt.value < minInt.value)
+                    var randomRange = maxInt.value - minInt.value + 1;
+                    if (randomRange <= 0)
                         Error ("RANDOM was called with minimum as " + minInt.value + " and maximum as " + maxInt.value + ". The maximum must be larger");
 
-                    var resultSeed = state.storySeed + state.randomIndex;
+                    var resultSeed = state.storySeed + state.previousRandom;
                     var random = new Random(resultSeed);
 
-                    var chosenValue = random.Next (minInt.value, maxInt.value+1);// //(random.Next () % randomRange) + minInt.value;
+                    var nextRandom = random.Next ();
+                    var chosenValue = (nextRandom % randomRange) + minInt.value;
                     state.PushEvaluationStack (new IntValue (chosenValue));
 
                     // Next random number (rather than keeping the Random object around)
-                    state.randomIndex++;
+                    state.previousRandom = nextRandom;
                     break;
 
                 case ControlCommand.CommandType.SeedRandom:
@@ -844,6 +845,10 @@ bool PerformLogicAndFlowControl(Runtime.Object contentObj)
 
                     // Story seed affects both RANDOM and shuffle behaviour
                     state.storySeed = seed.value;
+                    state.previousRandom = 0;
+
+                    // SEED_RANDOM returns nothing.
+                    state.PushEvaluationStack (new Runtime.Void ());
                     break;
 
                 case ControlCommand.CommandType.VisitIndex:

diff --git a/ink-engine-runtime/StoryState.cs b/ink-engine-runtime/StoryState.cs
@@ -73,7 +73,7 @@ public int VisitCountAtPathString(string pathString)
         internal Dictionary<string, int> turnIndices { get; private set; }
         internal int currentTurnIndex { get; private set; }
         internal int storySeed { get; set; }
-        internal int randomIndex { get; set; }
+        internal int previousRandom { get; set; }
         internal bool didSafeExit { get; set; }
 
         internal Story story { get; set; }
@@ -168,7 +168,7 @@ internal StoryState (Story story)
             // Seed the shuffle random numbers
             int timeSeed = DateTime.Now.Millisecond;
             storySeed = (new Random (timeSeed)).Next () % 100;
-            randomIndex = 0;
+            previousRandom = 0;
 
             currentChoices = new List<Choice> ();
 
@@ -216,7 +216,7 @@ internal StoryState Copy()
             copy.turnIndices = new Dictionary<string, int> (turnIndices);
             copy.currentTurnIndex = currentTurnIndex;
             copy.storySeed = storySeed;
-            copy.randomIndex = randomIndex;
+            copy.previousRandom = previousRandom;
 
             copy.didSafeExit = didSafeExit;
 
@@ -274,7 +274,7 @@ public Dictionary<string, object> jsonToken
                 obj ["turnIndices"] = Json.IntDictionaryToJObject (turnIndices);
                 obj ["turnIdx"] = currentTurnIndex;
                 obj ["storySeed"] = storySeed;
-                obj ["randomIndex"] = randomIndex;
+                obj ["previousRandom"] = previousRandom;
 
                 obj ["inkSaveVersion"] = kInkSaveStateVersion;
 
@@ -322,7 +322,7 @@ public Dictionary<string, object> jsonToken
                 turnIndices = Json.JObjectToIntDictionary ((Dictionary<string, object>)jObject ["turnIndices"]);
                 currentTurnIndex = (int)jObject ["turnIdx"];
                 storySeed = (int)jObject ["storySeed"];
-                randomIndex = (int)jObject ["randomIndex"];
+                previousRandom = (int)jObject ["previousRandom"];
 
 				object jChoiceThreadsObj = null;
 				jObject.TryGetValue("choiceThreads", out jChoiceThreadsObj);

diff --git a/inklecate/ParsedHierarchy/FunctionCall.cs b/inklecate/ParsedHierarchy/FunctionCall.cs
@@ -80,7 +80,7 @@ public override void GenerateIntoContainer (Runtime.Container container)
             } 
 
             else if (isSeedRandom) {
-                if (arguments.Count != 2)
+                if (arguments.Count != 1)
                     Error ("SEED_RANDOM should take 1 parameter - an integer seed");
 
                 var num = arguments [0] as Number;