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) noexcept
20 bool GaloisLFSR::operator ()() noexcept {
21 bool result = state & 1;
24 state |= 0x8000000000000000;
27 state &= 0x7FFFFFFFFFFFFFFF;
33 SimplexNoise::SimplexNoise(unsigned int seed) noexcept
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];
52 perm12[i] = perm[i] % 12;
53 perm12[i + 256] = perm12[i];
58 float SimplexNoise::operator ()(const glm::vec3 &in) const noexcept {
59 float skew = (in.x + in.y + in.z) * one_third;
61 glm::vec3 skewed(glm::floor(in + skew));
62 float tr = (skewed.x + skewed.y + skewed.z) * one_sixth;
64 glm::vec3 unskewed(skewed - tr);
66 offset[0] = in - unskewed;
68 glm::vec3 second, third;
70 if (offset[0].x >= offset[0].y) {
71 if (offset[0].y >= offset[0].z) {
72 second = { 1.0f, 0.0f, 0.0f };
73 third = { 1.0f, 1.0f, 0.0f };
74 } else if (offset[0].x >= offset[0].z) {
75 second = { 1.0f, 0.0f, 0.0f };
76 third = { 1.0f, 0.0f, 1.0f };
78 second = { 0.0f, 0.0f, 1.0f };
79 third = { 1.0f, 0.0f, 1.0f };
81 } else if (offset[0].y < offset[0].z) {
82 second = { 0.0f, 0.0f, 1.0f };
83 third = { 0.0f, 1.0f, 1.0f };
84 } else if (offset[0].x < offset[0].z) {
85 second = { 0.0f, 1.0f, 0.0f };
86 third = { 0.0f, 1.0f, 1.0f };
88 second = { 0.0f, 1.0f, 0.0f };
89 third = { 1.0f, 1.0f, 0.0f };
92 offset[1] = offset[0] - second + one_sixth;
93 offset[2] = offset[0] - third + one_third;
94 offset[3] = offset[0] - 0.5f;
96 unsigned char index[3] = {
97 (unsigned char)(skewed.x),
98 (unsigned char)(skewed.y),
99 (unsigned char)(skewed.z),
101 unsigned char corner[4] = {
102 Perm12(index[0] + Perm(index[1] + Perm(index[2]))),
103 Perm12(index[0] + int(second.x) + Perm(index[1] + int(second.y) + Perm(index[2] + int(second.z)))),
104 Perm12(index[0] + int(third.x) + Perm(index[1] + int(third.y) + Perm(index[2] + int(third.z)))),
105 Perm12(index[0] + 1 + Perm(index[1] + 1 + Perm(index[2] + 1))),
109 for (size_t i = 0; i < 4; ++i) {
110 t[i] = 0.6f - dot(offset[i], offset[i]);
115 n[i] = t[i] * t[i] * dot(Grad(corner[i]), offset[i]);
119 return 32.0f * (n[0] + n[1] + n[2] + n[3]);
123 unsigned char SimplexNoise::Perm(size_t idx) const noexcept {
127 unsigned char SimplexNoise::Perm12(size_t idx) const noexcept {
131 const glm::vec3 &SimplexNoise::Grad(unsigned char idx) const noexcept {
136 WorleyNoise::WorleyNoise(unsigned int seed) noexcept
142 float WorleyNoise::operator ()(const glm::vec3 &in) const noexcept {
143 glm::vec3 center = floor(in);
145 float closest = 1.0f; // cannot be farther away than 1.0
147 for (int z = -1; z <= 1; ++z) {
148 for (int y = -1; y <= 1; ++y) {
149 for (int x = -1; x <= 1; ++x) {
150 glm::vec3 cube(center.x + x, center.y + y, center.z + z);
151 unsigned int cube_rand =
152 (unsigned(cube.x) * 130223) ^
153 (unsigned(cube.y) * 159899) ^
154 (unsigned(cube.z) * 190717) ^
157 for (int i = 0; i < num_points; ++i) {
158 glm::vec3 point(cube);
159 cube_rand = 190667 * cube_rand + 109807;
160 point.x += float(cube_rand % 262144) / 262144.0f;
161 cube_rand = 135899 * cube_rand + 189169;
162 point.y += float(cube_rand % 262144) / 262144.0f;
163 cube_rand = 159739 * cube_rand + 112139;
164 point.z += float(cube_rand % 262144) / 262144.0f;
166 glm::vec3 diff(in - point);
167 float distance = sqrt(dot(diff, diff));
168 if (distance < closest) {
176 // closest ranges (0, 1), so normalizing to (-1,1) is trivial
177 // though heavily biased towards lower numbers
178 return 2.0f * closest - 1.0f;