diff --git a/c++/perspective/src/generator.cpp b/c++/perspective/src/generator.cpp
index d80baec..48bc1f7 100644
--- a/c++/perspective/src/generator.cpp
+++ b/c++/perspective/src/generator.cpp
@@ -29,8 +29,9 @@ Real
 Generator::random(const ULongIntVector2 &coord, int index) const {
 	ULongInt seed = random(random(coord.x) ^ seeds_x()[index]);
 	seed = random(seed ^ random(coord.y) ^ seeds_y()[index]);
-	seed = random(seed ^ random(coord.x) ^ random(coord.y));
-	return Real(seed)/Real(ULLONG_MAX)*Real(2) - Real(1);
+	const ULongInt x = seed = random(seed ^ random(coord.x) ^ random(coord.y));
+	const ULongInt y = seed = random(seed);
+	return random_to_normal(x, y);
 }
 
 Vector4
@@ -93,6 +94,9 @@ Generator::generate(const ULongIntVector2 &coord, bool shrink_cache) const {
 						 + generate(ULongIntVector2(coord.x, coord.y + level)) )*0.25;
 			}
 		}
+
+		for(int j = 0; j < 4; ++j)
+			value[j] = mirror_repeat(value[j]);
 	}
 	i->second.in_use = false;
 	
diff --git a/c++/perspective/src/generator.h b/c++/perspective/src/generator.h
index 3d44432..92cfc77 100644
--- a/c++/perspective/src/generator.h
+++ b/c++/perspective/src/generator.h
@@ -43,8 +43,18 @@ public:
 		++x;
 		return x;
 	}
+
 	static inline Real random_to_real(ULongInt x)
 		{ return Real(x)/Real(ULLONG_MAX); }
+	static inline Real random_to_normal(ULongInt x, ULongInt y)
+		{ return sqrt(-2*log(random_to_real(x))) * sin(2*M_PI*random_to_real(y)); }
+	
+	static inline Real mirror_repeat(Real x) {
+		x *= 0.5;
+		x -= floor(x);
+		x *= 2;
+		return x > 1 ? 2 - x : x;
+	}
 
 private:
 	const ULongInt one;