use constantly seeded random

Source/CharacterPlugin/Private/Crowds/Predictive.cpp

@@ -11,6 +11,11 @@
 #include "DrawDebugHelpers.h"
 #include "Kismet/GameplayStatics.h"
 
+UPredictive::UPredictive()
+{
+	RandomStream = FRandomStream(0);
+}
+
 /**
 *	Implementation based on the following paper:
 *   Karamouzas et al.: 
@@ -186,8 +191,8 @@ void UPredictive::PostProcessVelocity(float LastDeltaTime, FVector& Velocity)
 	/************************************************************************/
 	/* NOISE TO AVOID DEADLOCKS AND INTRODUCE VARIATIONS					*/
 	/************************************************************************/
-	float angle = FMath::RandRange(0.0f, 2.0f * PI);
-	float dist = FMath::RandRange(0.0f, 0.001f);
+	float angle = RandomStream.FRandRange(0.0f, 2.0f * PI);
+	float dist = RandomStream.FRandRange(0.0f, 0.001f);
 	force += dist * FVector2D(cos(angle), sin(angle));
 	
 	// Cap the force to maxAcceleration

Source/CharacterPlugin/Private/VHMovement.cpp

@@ -31,6 +31,8 @@ UVHMovement::UVHMovement()
 	// Set this component to be initialized when the game starts, and to be ticked every frame.  You can turn these features
 	// off to improve performance if you don't need them.
 	PrimaryComponentTick.bCanEverTick = true;
+
+	RandomStream = FRandomStream(0);
 }
 
 
@@ -402,8 +404,7 @@ TArray<AWaypoint*> UVHMovement::ShuffleArray(TArray<AWaypoint*> myArray)
 		int32 LastIndex = myArray.Num() - 1;
 		for (int32 i = 0; i <= LastIndex; ++i)
 		{
-			srand(time(0)-i);
-			int32 Index = rand() % LastIndex;
+			int32 Index = RandomStream.FRandRange(0,LastIndex);
 			if (i != Index)
 			{
 				myArray.Swap(Index, i);

Source/CharacterPlugin/Public/Crowds/Predictive.h

@@ -16,6 +16,8 @@ class CHARACTERPLUGIN_API UPredictive : public UVelocityPostProcessorComponent
 	GENERATED_BODY()
 
 public:
+	UPredictive();
+	
 	virtual void PostProcessVelocity(float LastDeltaTime, FVector& Velocity) override;
 
 	// These following values come directly from the Karamouzas paper (see cpp)
@@ -63,4 +65,6 @@ public:
 
 private:
 	float RayCircleTTC(const FVector2D& Dir, const FVector2D& Center, float Radius);
+
+	FRandomStream RandomStream;
 };

Source/CharacterPlugin/Public/VHMovement.h

@@ -181,4 +181,6 @@ private:
 	UFUNCTION(BlueprintCallable)
 		void WaypointMovement();
 
+	FRandomStream RandomStream;
+
 };