simplified block face stuff

[blank.git] / src / noise.cpp

diff --git a/src/noise.cpp b/src/noise.cpp
index 4400a1a4988e0b57aee77e7d6b7ae73a522a4441..8b716140e78c5b301fbd00a383778eb482e9166f 100644 (file)
--- a/src/noise.cpp
+++ b/src/noise.cpp
@@ -12,6 +12,24 @@ constexpr float one_sixth = 1.0f/6.0f;
 
 namespace blank {
 
+GaloisLFSR::GaloisLFSR(std::uint64_t seed)
+: state(seed) {
+
+}
+
+bool GaloisLFSR::operator ()() {
+       bool result = state & 1;
+       state >>= 1;
+       if (result) {
+               state |= 0x8000000000000000;
+               state ^= mask;
+       } else {
+               state &= 0x7FFFFFFFFFFFFFFF;
+       }
+       return result;
+}
+
+
 SimplexNoise::SimplexNoise(unsigned int seed)
 : grad({
        {  1.0f,  1.0f,  0.0f },
@@ -27,10 +45,9 @@ 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];
        }
 }
@@ -119,7 +136,7 @@ WorleyNoise::WorleyNoise(unsigned int seed)
 float WorleyNoise::operator ()(const glm::vec3 &in) const {
        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;
 }
 
 }