don't fix collisions in RK4 substeps

[blank.git] / src / rand / noise.cpp

diff --git a/src/rand/noise.cpp b/src/rand/noise.cpp
index e4ad3102e006795d3407b1576ceb4897fb35327f..b3a9bc8cd2c58b237c2e3ff23ccdf4aaa6972bfc 100644 (file)
--- a/src/rand/noise.cpp
+++ b/src/rand/noise.cpp
@@ -28,6 +28,50 @@ SimplexNoise::SimplexNoise(std::uint64_t seed) noexcept
        {  0.0f, -1.0f,  1.0f },
        {  0.0f,  1.0f, -1.0f },
        {  0.0f, -1.0f, -1.0f },
+})
+, second_ints({
+                    // x>y x>z y>z
+       { 0, 0, 1 }, //  0   0   0  ZYX
+       { 0, 1, 0 }, //  0   0   1  YZX
+       { 0, 0, 1 }, //  0   1   0  illogical, but ZYX
+       { 0, 1, 0 }, //  0   1   1  YXZ
+       { 0, 0, 1 }, //  1   0   0  ZXY
+       { 1, 0, 0 }, //  1   0   1  illogical, but XYZ
+       { 1, 0, 0 }, //  1   1   0  XZY
+       { 1, 0, 0 }, //  1   1   1  XYZ
+})
+, third_ints({
+                    // x>y x>z y>z
+       { 0, 1, 1 }, //  0   0   0  ZYX
+       { 0, 1, 1 }, //  0   0   1  YZX
+       { 0, 1, 1 }, //  0   1   0  illogical, but ZYX
+       { 1, 1, 0 }, //  0   1   1  YXZ
+       { 1, 0, 1 }, //  1   0   0  ZXY
+       { 1, 1, 0 }, //  1   0   1  illogical, but XYZ
+       { 1, 0, 1 }, //  1   1   0  XZY
+       { 1, 1, 0 }, //  1   1   1  XYZ
+})
+, second_floats({
+                             // x>y x>z y>z
+       { 0.0f, 0.0f, 1.0f }, //  0   0   0  ZYX
+       { 0.0f, 1.0f, 0.0f }, //  0   0   1  YZX
+       { 0.0f, 0.0f, 1.0f }, //  0   1   0  illogical, but ZYX
+       { 0.0f, 1.0f, 0.0f }, //  0   1   1  YXZ
+       { 0.0f, 0.0f, 1.0f }, //  1   0   0  ZXY
+       { 1.0f, 0.0f, 0.0f }, //  1   0   1  illogical, but XYZ
+       { 1.0f, 0.0f, 0.0f }, //  1   1   0  XZY
+       { 1.0f, 0.0f, 0.0f }, //  1   1   1  XYZ
+})
+, third_floats({
+                             // x>y x>z y>z
+       { 0.0f, 1.0f, 1.0f }, //  0   0   0  ZYX
+       { 0.0f, 1.0f, 1.0f }, //  0   0   1  YZX
+       { 0.0f, 1.0f, 1.0f }, //  0   1   0  illogical, but ZYX
+       { 1.0f, 1.0f, 0.0f }, //  0   1   1  YXZ
+       { 1.0f, 0.0f, 1.0f }, //  1   0   0  ZXY
+       { 1.0f, 1.0f, 0.0f }, //  1   0   1  illogical, but XYZ
+       { 1.0f, 0.0f, 1.0f }, //  1   1   0  XZY
+       { 1.0f, 1.0f, 0.0f }, //  1   1   1  XYZ
 }) {
        GaloisLFSR random(seed ^ 0x0123456789ACBDEF);
        unsigned char value;
@@ -50,34 +94,20 @@ float SimplexNoise::operator ()(const glm::vec3 &in) const noexcept {
        glm::vec3 unskewed(skewed - tr);
        glm::vec3 relative(in - unskewed);
 
-       glm::vec3 second, third;
-
-       if (relative.x >= relative.y) {
-               if (relative.y >= relative.z) {
-                       second = { 1, 0, 0 };
-                       third = { 1, 1, 0 };
-               } else if (relative.x >= relative.z) {
-                       second = { 1, 0, 0 };
-                       third = { 1, 0, 1 };
-               } else {
-                       second = { 0, 0, 1 };
-                       third = { 1, 0, 1 };
-               }
-       } else if (relative.y < relative.z) {
-               second = { 0, 0, 1 };
-               third = { 0, 1, 1 };
-       } else if (relative.x < relative.z) {
-               second = { 0, 1, 0 };
-               third = { 0, 1, 1 };
-       } else {
-               second = { 0, 1, 0 };
-               third = { 1, 1, 0 };
-       }
+       bool x_ge_y = relative.x >= relative.y;
+       bool x_ge_z = relative.x >= relative.z;
+       bool y_ge_z = relative.y >= relative.z;
+       unsigned int st = (x_ge_y << 2) | (x_ge_z << 1) | y_ge_z;
+
+       glm::ivec3 second_int(second_ints[st]);
+       glm::ivec3 third_int(third_ints[st]);
+       glm::vec3 second_float(second_floats[st]);
+       glm::vec3 third_float(third_floats[st]);
 
        glm::vec3 offset[4] = {
                in - unskewed,
-               relative - second + one_sixth,
-               relative - third + one_third,
+               relative - second_float + one_sixth,
+               relative - third_float + one_third,
                relative - 0.5f,
        };
 
@@ -89,37 +119,31 @@ float SimplexNoise::operator ()(const glm::vec3 &in) const noexcept {
 
        float n = 0.0f;
 
+       // I know 0.6 is wrong, but for some reason it looks better than 0.5
+
        // 0
-       float t = 0.6f - dot(offset[0], offset[0]);
-       if (t > 0.0f) {
-               t *= t;
-               int corner = Perm12(index[0] + Perm(index[1] + Perm(index[2])));
-               n += t * t * dot(Grad(corner), offset[0]);
-       }
+       float t = glm::clamp(0.6f - dot(offset[0], offset[0]), 0.0f, 1.0f);
+       t *= t;
+       int corner = Perm12(index[0] + Perm(index[1] + Perm(index[2])));
+       n += t * t * dot(Grad(corner), offset[0]);
 
        // 1
-       t = 0.6f - dot(offset[1], offset[1]);
-       if (t > 0.0f) {
-               t *= t;
-               int corner = Perm12(index[0] + int(second.x) + Perm(index[1] + int(second.y) + Perm(index[2] + int(second.z))));
-               n += t * t * dot(Grad(corner), offset[1]);
-       }
+       t = glm::clamp(0.6f - dot(offset[1], offset[1]), 0.0f, 1.0f);
+       t *= t;
+       corner = Perm12(index[0] + second_int.x + Perm(index[1] + second_int.y + Perm(index[2] + second_int.z)));
+       n += t * t * dot(Grad(corner), offset[1]);
 
        // 2
-       t = 0.6f - dot(offset[2], offset[2]);
-       if (t > 0.0f) {
-               t *= t;
-               int corner = Perm12(index[0] + int(third.x) + Perm(index[1] + int(third.y) + Perm(index[2] + int(third.z))));
-               n += t * t * dot(Grad(corner), offset[2]);
-       }
+       t = glm::clamp(0.6f - dot(offset[2], offset[2]), 0.0f, 1.0f);
+       t *= t;
+       corner = Perm12(index[0] + third_int.x + Perm(index[1] + third_int.y + Perm(index[2] + third_int.z)));
+       n += t * t * dot(Grad(corner), offset[2]);
 
        // 3
-       t = 0.6f - dot(offset[3], offset[3]);
-       if (t > 0.0f) {
-               t *= t;
-               int corner = Perm12(index[0] + 1 + Perm(index[1] + 1 + Perm(index[2] + 1)));
-               n += t * t * dot(Grad(corner), offset[3]);
-       }
+       t = glm::clamp(0.6f - dot(offset[3], offset[3]), 0.0f, 1.0f);
+       t *= t;
+       corner = Perm12(index[0] + 1 + Perm(index[1] + 1 + Perm(index[2] + 1)));
+       n += t * t * dot(Grad(corner), offset[3]);
 
        return 32.0f * n;
 }