improve consistency

PerlinNoise.hpp

@@ -39,17 +39,17 @@ namespace siv
 
 		std::int32_t p[512];
 
-		double fade(double t) const noexcept
+		static double Fade(double t) noexcept
 		{
 			return t * t * t * (t * (t * 6 - 15) + 10);
 		}
 
-		double lerp(double t, double a, double b) const noexcept
+		static double Lerp(double t, double a, double b) noexcept
 		{
 			return a + t * (b - a);
 		}
 
-		double grad(std::int32_t hash, double x, double y, double z) const noexcept
+		static double Grad(std::int32_t hash, double x, double y, double z) noexcept
 		{
 			const std::int32_t h = hash & 15;
 			const double u = h < 8 ? x : y;
@@ -66,7 +66,7 @@ namespace siv
 
 		void reseed(std::uint32_t seed)
 		{
-			for (std::int32_t i = 0; i < 256; ++i)
+			for (size_t i = 0; i < 256; ++i)
 			{
 				p[i] = i;
 			}
@@ -99,21 +99,21 @@ namespace siv
 			y -= std::floor(y);
 			z -= std::floor(z);
 
-			const double u = fade(x);
-			const double v = fade(y);
-			const double w = fade(z);
-
-			const int A = p[X] + Y, AA = p[A] + Z, AB = p[A + 1] + Z;
-			const int B = p[X + 1] + Y, BA = p[B] + Z, BB = p[B + 1] + Z;
-
-			return lerp(w, lerp(v, lerp(u, grad(p[AA], x, y, z),
-				grad(p[BA], x - 1, y, z)),
-				lerp(u, grad(p[AB], x, y - 1, z),
-				grad(p[BB], x - 1, y - 1, z))),
-				lerp(v, lerp(u, grad(p[AA + 1], x, y, z - 1),
-				grad(p[BA + 1], x - 1, y, z - 1)),
-				lerp(u, grad(p[AB + 1], x, y - 1, z - 1),
-				grad(p[BB + 1], x - 1, y - 1, z - 1))));
+			const double u = Fade(x);
+			const double v = Fade(y);
+			const double w = Fade(z);
+
+			const std::int32_t A = p[X] + Y, AA = p[A] + Z, AB = p[A + 1] + Z;
+			const std::int32_t B = p[X + 1] + Y, BA = p[B] + Z, BB = p[B + 1] + Z;
+
+			return Lerp(w, Lerp(v, Lerp(u, Grad(p[AA], x, y, z),
+				Grad(p[BA], x - 1, y, z)),
+				Lerp(u, Grad(p[AB], x, y - 1, z),
+				Grad(p[BB], x - 1, y - 1, z))),
+				Lerp(v, Lerp(u, Grad(p[AA + 1], x, y, z - 1),
+				Grad(p[BA + 1], x - 1, y, z - 1)),
+				Lerp(u, Grad(p[AB + 1], x, y - 1, z - 1),
+				Grad(p[BB + 1], x - 1, y - 1, z - 1))));
 		}
 
 		double octaveNoise(double x, std::int32_t octaves) const