1 files changed, 147 insertions, 0 deletions
diff --git a/source/blender/blenlib/BLI_rand.hh b/source/blender/blenlib/BLI_rand.hh
new file mode 100644
index 00000000000..7a98ee0f2bb
--- /dev/null
+++ b/source/blender/blenlib/BLI_rand.hh
@@ -0,0 +1,147 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+/** \file
+ * \ingroup bli
+ */
+
+#ifndef __BLI_RAND_HH__
+#define __BLI_RAND_HH__
+
+#include "BLI_float2.hh"
+#include "BLI_float3.hh"
+#include "BLI_math.h"
+#include "BLI_span.hh"
+#include "BLI_utildefines.h"
+
+namespace blender {
+
+class RandomNumberGenerator {
+ private:
+  uint64_t x_;
+
+ public:
+  RandomNumberGenerator(uint32_t seed = 0)
+  {
+    this->seed(seed);
+  }
+
+  /**
+   * Set the seed for future random numbers.
+   */
+  void seed(uint32_t seed)
+  {
+    constexpr uint64_t lowseed = 0x330E;
+    x_ = (((uint64_t)seed) << 16) | lowseed;
+  }
+
+  void seed_random(uint32_t seed);
+
+  uint32_t get_uint32()
+  {
+    this->step();
+    return (uint32_t)(x_ >> 17);
+  }
+
+  int32_t get_int32()
+  {
+    this->step();
+    return (int32_t)(x_ >> 17);
+  }
+
+  /**
+   * \return Random value (0..N), but never N.
+   */
+  int32_t get_int32(int32_t max_exclusive)
+  {
+    BLI_assert(max_exclusive > 0);
+    return this->get_int32() % max_exclusive;
+  }
+
+  /**
+   * \return Random value (0..1), but never 1.0.
+   */
+  double get_double()
+  {
+    return (double)this->get_int32() / 0x80000000;
+  }
+
+  /**
+   * \return Random value (0..1), but never 1.0.
+   */
+  float get_float()
+  {
+    return (float)this->get_int32() / 0x80000000;
+  }
+
+  template<typename T> void shuffle(MutableSpan<T> values)
+  {
+    /* Cannot shuffle arrays of this size yet. */
+    BLI_assert(values.size() <= INT32_MAX);
+
+    for (int i = values.size() - 1; i >= 2; i--) {
+      int j = this->get_int32(i);
+      if (i != j) {
+        std::swap(values[i], values[j]);
+      }
+    }
+  }
+
+  /**
+   * Compute uniformly distributed barycentric coordinates.
+   */
+  float3 get_barycentric_coordinates()
+  {
+    float rand1 = this->get_float();
+    float rand2 = this->get_float();
+
+    if (rand1 + rand2 > 1.0f) {
+      rand1 = 1.0f - rand1;
+      rand2 = 1.0f - rand2;
+    }
+
+    return float3(rand1, rand2, 1.0f - rand1 - rand2);
+  }
+
+  float2 get_unit_float2();
+  float3 get_unit_float3();
+  float2 get_triangle_sample(float2 v1, float2 v2, float2 v3);
+  void get_bytes(MutableSpan<char> r_bytes);
+
+  /**
+   * Simulate getting \a n random values.
+   */
+  void skip(int64_t n)
+  {
+    while (n--) {
+      this->step();
+    }
+  }
+
+ private:
+  void step()
+  {
+    constexpr uint64_t multiplier = 0x5DEECE66Dll;
+    constexpr uint64_t addend = 0xB;
+    constexpr uint64_t mask = 0x0000FFFFFFFFFFFFll;
+
+    x_ = (multiplier * x_ + addend) & mask;
+  }
+};
+
+}  // namespace blender
+
+#endif /* __BLI_RAND_HH__ */