X-Git-Url: http://git.localhorst.tv/?a=blobdiff_plain;f=src%2Fnoise.cpp;h=a5a9a2057957f361d449581eec3cbd29d94aeae6;hb=76b3ec0f6aa0dacf6d4944a2787991f3585299e8;hp=4400a1a4988e0b57aee77e7d6b7ae73a522a4441;hpb=42dea80c2cffb75a5721d1cbf0cdd6277f4d520d;p=blank.git

diff --git a/src/noise.cpp b/src/noise.cpp
index 4400a1a..a5a9a20 100644
--- a/src/noise.cpp
+++ b/src/noise.cpp
@@ -12,7 +12,25 @@ constexpr float one_sixth = 1.0f/6.0f;
 
 namespace blank {
 
-SimplexNoise::SimplexNoise(unsigned int seed)
+GaloisLFSR::GaloisLFSR(std::uint64_t seed) noexcept
+: state(seed) {
+
+}
+
+bool GaloisLFSR::operator ()() noexcept {
+	bool result = state & 1;
+	state >>= 1;
+	if (result) {
+		state |= 0x8000000000000000;
+		state ^= mask;
+	} else {
+		state &= 0x7FFFFFFFFFFFFFFF;
+	}
+	return result;
+}
+
+
+SimplexNoise::SimplexNoise(unsigned int seed) noexcept
 : grad({
 	{  1.0f,  1.0f,  0.0f },
 	{ -1.0f,  1.0f,  0.0f },
@@ -27,16 +45,15 @@ SimplexNoise::SimplexNoise(unsigned int seed)
 	{  0.0f,  1.0f, -1.0f },
 	{  0.0f, -1.0f, -1.0f },
 }) {
-	unsigned int val = seed;
+	GaloisLFSR random(seed ^ 0x0123456789ACBDEF);
 	for (size_t i = 0; i < 256; ++i) {
-		val = 2346765 * val + 6446345;
-		perm[i] = val % 256;
+		random(perm[i]);
 		perm[i + 256] = perm[i];
 	}
 }
 
 
-float SimplexNoise::operator ()(const glm::vec3 &in) const {
+float SimplexNoise::operator ()(const glm::vec3 &in) const noexcept {
 	float skew = (in.x + in.y + in.z) * one_third;
 
 	glm::vec3 skewed(glm::floor(in + skew));
@@ -101,25 +118,25 @@ float SimplexNoise::operator ()(const glm::vec3 &in) const {
 }
 
 
-unsigned char SimplexNoise::Perm(size_t idx) const {
+unsigned char SimplexNoise::Perm(size_t idx) const noexcept {
 	return perm[idx];
 }
 
-const glm::vec3 &SimplexNoise::Grad(size_t idx) const {
+const glm::vec3 &SimplexNoise::Grad(size_t idx) const noexcept {
 	return grad[idx % 12];
 }
 
 
-WorleyNoise::WorleyNoise(unsigned int seed)
+WorleyNoise::WorleyNoise(unsigned int seed) noexcept
 : seed(seed)
 , num_points(8) {
 
 }
 
-float WorleyNoise::operator ()(const glm::vec3 &in) const {
+float WorleyNoise::operator ()(const glm::vec3 &in) const noexcept {
 	glm::vec3 center = floor(in);
 
-	float closest = 4.0f;
+	float closest = 1.0f;  // cannot be farther away than 1.0
 
 	for (int z = -1; z <= 1; ++z) {
 		for (int y = -1; y <= 1; ++y) {
@@ -141,7 +158,7 @@ float WorleyNoise::operator ()(const glm::vec3 &in) const {
 					point.z += float(cube_rand % 200000) / 200000.0f;
 
 					glm::vec3 diff(in - point);
-					float distance = dot(diff, diff);
+					float distance = sqrt(dot(diff, diff));
 					if (distance < closest) {
 						closest = distance;
 					}
@@ -150,7 +167,9 @@ float WorleyNoise::operator ()(const glm::vec3 &in) const {
 		}
 	}
 
-	return closest;
+	// closest ranges (0, 1), so normalizing to (-1,1) is trivial
+	// though heavily biased towards lower numbers
+	return 2.0f * closest - 1.0f;
 }
 
 }