Repo created

iphone/Maps/Core/Location/MountainElevationGenerator.hpp

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+#pragma once
+
+#include <ctime>
+#include <random>
+
+class MountainElevationGenerator
+{
+  static double constexpr kRandom{-1.};
+
+  std::mt19937_64 rng;
+
+  double const minElevation;
+  double const maxElevation;
+  double const maxSlopeChange;
+
+  std::normal_distribution<double> slopeChangeDist;
+
+  double currentElevation;
+  double currentSlope;
+
+  double ValueOrRandomInRange(double value, double min, double max)
+  {
+    if (value != kRandom)
+      return value;
+
+    return std::uniform_int_distribution<>(min, max)(rng);
+  }
+
+public:
+  MountainElevationGenerator(double minElevation = kRandom, double maxElevation = kRandom,
+                             double startElevation = kRandom, double maxSlopeChange = kRandom,
+                             time_t seed = std::time(nullptr))
+    : rng(seed)
+    , minElevation(ValueOrRandomInRange(minElevation, 0., 2000.))
+    , maxElevation(ValueOrRandomInRange(maxElevation, 3000., 7000.))
+    , maxSlopeChange(ValueOrRandomInRange(maxSlopeChange, 1., 5.))
+    , slopeChangeDist(0.0, maxSlopeChange)
+    , currentElevation(ValueOrRandomInRange(startElevation, minElevation, maxElevation))
+    , currentSlope(0.0)
+  {}
+
+  double NextElevation()
+  {
+    // Change the slope gradually
+    currentSlope += slopeChangeDist(rng);
+
+    // Limit maximum steepness
+    currentSlope = std::max(-maxSlopeChange, std::min(maxSlopeChange, currentSlope));
+
+    // Update elevation based on current slope
+    currentElevation += currentSlope;
+
+    // Ensure we stay within elevation bounds
+    if (currentElevation < minElevation)
+    {
+      currentElevation = minElevation;
+      currentSlope = std::abs(currentSlope) * 0.5;  // Bounce back up
+    }
+    if (currentElevation > maxElevation)
+    {
+      currentElevation = maxElevation;
+      currentSlope = -std::abs(currentSlope) * 0.5;  // Start going down
+    }
+
+    return currentElevation;
+  }
+};