8 constexpr float one_third = 1.0f/3.0f;
9 constexpr float one_sixth = 1.0f/6.0f;
15 GaloisLFSR::GaloisLFSR(std::uint64_t seed)
20 bool GaloisLFSR::operator ()() {
21 bool result = state & 1;
24 state |= 0x8000000000000000;
27 state &= 0x7FFFFFFFFFFFFFFF;
33 SimplexNoise::SimplexNoise(unsigned int seed)
36 { -1.0f, 1.0f, 0.0f },
37 { 1.0f, -1.0f, 0.0f },
38 { -1.0f, -1.0f, 0.0f },
40 { -1.0f, 0.0f, 1.0f },
41 { 1.0f, 0.0f, -1.0f },
42 { -1.0f, 0.0f, -1.0f },
44 { 0.0f, -1.0f, 1.0f },
45 { 0.0f, 1.0f, -1.0f },
46 { 0.0f, -1.0f, -1.0f },
48 GaloisLFSR random(seed ^ 0x0123456789ACBDEF);
49 for (size_t i = 0; i < 256; ++i) {
51 perm[i + 256] = perm[i];
56 float SimplexNoise::operator ()(const glm::vec3 &in) const {
57 float skew = (in.x + in.y + in.z) * one_third;
59 glm::vec3 skewed(glm::floor(in + skew));
60 float tr = (skewed.x + skewed.y + skewed.z) * one_sixth;
62 glm::vec3 unskewed(skewed - tr);
64 offset[0] = in - unskewed;
66 glm::vec3 second, third;
68 if (offset[0].x >= offset[0].y) {
69 if (offset[0].y >= offset[0].z) {
70 second = { 1.0f, 0.0f, 0.0f };
71 third = { 1.0f, 1.0f, 0.0f };
72 } else if (offset[0].x >= offset[0].z) {
73 second = { 1.0f, 0.0f, 0.0f };
74 third = { 1.0f, 0.0f, 1.0f };
76 second = { 0.0f, 0.0f, 1.0f };
77 third = { 1.0f, 0.0f, 1.0f };
79 } else if (offset[0].y < offset[0].z) {
80 second = { 0.0f, 0.0f, 1.0f };
81 third = { 0.0f, 1.0f, 1.0f };
82 } else if (offset[0].x < offset[0].z) {
83 second = { 0.0f, 1.0f, 0.0f };
84 third = { 0.0f, 1.0f, 1.0f };
86 second = { 0.0f, 1.0f, 0.0f };
87 third = { 1.0f, 1.0f, 0.0f };
90 offset[1] = offset[0] - second + one_sixth;
91 offset[2] = offset[0] - third + one_third;
92 offset[3] = offset[0] - 0.5f;
94 unsigned char index[3] = {
95 (unsigned char)(skewed.x),
96 (unsigned char)(skewed.y),
97 (unsigned char)(skewed.z),
100 Perm(index[0] + Perm(index[1] + Perm(index[2]))),
101 Perm(index[0] + second.x + Perm(index[1] + second.y + Perm(index[2] + second.z))),
102 Perm(index[0] + third.x + Perm(index[1] + third.y + Perm(index[2] + third.z))),
103 Perm(index[0] + 1 + Perm(index[1] + 1 + Perm(index[2] + 1))),
107 for (size_t i = 0; i < 4; ++i) {
108 t[i] = 0.6f - dot(offset[i], offset[i]);
113 n[i] = t[i] * t[i] * dot(Grad(corner[i]), offset[i]);
117 return 32.0f * (n[0] + n[1] + n[2] + n[3]);
121 unsigned char SimplexNoise::Perm(size_t idx) const {
125 const glm::vec3 &SimplexNoise::Grad(size_t idx) const {
126 return grad[idx % 12];
130 WorleyNoise::WorleyNoise(unsigned int seed)
136 float WorleyNoise::operator ()(const glm::vec3 &in) const {
137 glm::vec3 center = floor(in);
139 float closest = 1.0f; // cannot be farther away than 1.0
141 for (int z = -1; z <= 1; ++z) {
142 for (int y = -1; y <= 1; ++y) {
143 for (int x = -1; x <= 1; ++x) {
144 glm::tvec3<int> cube(center.x + x, center.y + y, center.z + z);
145 unsigned int cube_rand =
151 for (int i = 0; i < num_points; ++i) {
152 glm::vec3 point(cube);
153 cube_rand = 190667 * cube_rand + 109807;
154 point.x += float(cube_rand % 200000) / 200000.0f;
155 cube_rand = 135899 * cube_rand + 189169;
156 point.y += float(cube_rand % 200000) / 200000.0f;
157 cube_rand = 159739 * cube_rand + 112139;
158 point.z += float(cube_rand % 200000) / 200000.0f;
160 glm::vec3 diff(in - point);
161 float distance = sqrt(dot(diff, diff));
162 if (distance < closest) {
170 // closest ranges (0, 1), so normalizing to (-1,1) is trivial
171 // though heavily biased towards lower numbers
172 return 2.0f * closest - 1.0f;