be smart about numbers

[blank.git] / src / noise.cpp

diff --git a/src/noise.cpp b/src/noise.cpp
index c86f833ac3c126c894a53eeb5ad6df6c9c835d02..c66153be5b56579438844176f0ffe2aacaed46be 100644 (file)
--- 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 +45,17 @@ 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];
+               perm12[i] = perm[i] % 12;
+               perm12[i + 256] = perm12[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));
@@ -79,11 +98,11 @@ float SimplexNoise::operator ()(const glm::vec3 &in) const {
                (unsigned char)(skewed.y),
                (unsigned char)(skewed.z),
        };
-       size_t corner[4] = {
-               Perm(index[0] + Perm(index[1] + Perm(index[2]))),
-               Perm(index[0] + second.x + Perm(index[1] + second.y + Perm(index[2] + second.z))),
-               Perm(index[0] + third.x + Perm(index[1] + third.y + Perm(index[2] + third.z))),
-               Perm(index[0] + 1 + Perm(index[1] + 1 + Perm(index[2] + 1))),
+       unsigned char corner[4] = {
+               Perm12(index[0] + Perm(index[1] + Perm(index[2]))),
+               Perm12(index[0] + int(second.x) + Perm(index[1] + int(second.y) + Perm(index[2] + int(second.z)))),
+               Perm12(index[0] + int(third.x) + Perm(index[1] + int(third.y) + Perm(index[2] + int(third.z)))),
+               Perm12(index[0] + 1 + Perm(index[1] + 1 + Perm(index[2] + 1))),
        };
        float n[4];
        float t[4];
@@ -101,22 +120,26 @@ 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 {
-       return grad[idx % 12];
+unsigned char SimplexNoise::Perm12(size_t idx) const noexcept {
+       return perm12[idx];
+}
+
+const glm::vec3 &SimplexNoise::Grad(unsigned char idx) const noexcept {
+       return grad[idx];
 }
 
 
-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 = 1.0f;  // cannot be farther away than 1.0
@@ -124,21 +147,21 @@ float WorleyNoise::operator ()(const glm::vec3 &in) const {
        for (int z = -1; z <= 1; ++z) {
                for (int y = -1; y <= 1; ++y) {
                        for (int x = -1; x <= 1; ++x) {
-                               glm::tvec3<int> cube(center.x + x, center.y + y, center.z + z);
+                               glm::vec3 cube(center.x + x, center.y + y, center.z + z);
                                unsigned int cube_rand =
-                                       (cube.x * 130223) ^
-                                       (cube.y * 159899) ^
-                                       (cube.z * 190717) ^
+                                       (unsigned(cube.x) * 130223) ^
+                                       (unsigned(cube.y) * 159899) ^
+                                       (unsigned(cube.z) * 190717) ^
                                        seed;
 
                                for (int i = 0; i < num_points; ++i) {
                                        glm::vec3 point(cube);
                                        cube_rand = 190667 * cube_rand + 109807;
-                                       point.x += float(cube_rand % 200000) / 200000.0f;
+                                       point.x += float(cube_rand % 262144) / 262144.0f;
                                        cube_rand = 135899 * cube_rand + 189169;
-                                       point.y += float(cube_rand % 200000) / 200000.0f;
+                                       point.y += float(cube_rand % 262144) / 262144.0f;
                                        cube_rand = 159739 * cube_rand + 112139;
-                                       point.z += float(cube_rand % 200000) / 200000.0f;
+                                       point.z += float(cube_rand % 262144) / 262144.0f;
 
                                        glm::vec3 diff(in - point);
                                        float distance = sqrt(dot(diff, diff));