randomize creature properties a bit

[blobs.git] / src / math / Distribution.hpp

diff --git a/src/math/Distribution.hpp b/src/math/Distribution.hpp
new file mode 100644 (file)
index 0000000..7f444f8
--- /dev/null
+++ b/src/math/Distribution.hpp
@@ -0,0 +1,38 @@
+#ifndef BLOBS_MATH_DISTRIBUTION_HPP_
+#define BLOBS_MATH_DISTRIBUTION_HPP_
+
+#include <cmath>
+
+
+namespace blobs {
+namespace math {
+
+class Distribution {
+
+public:
+       Distribution(double mean = 0.0, double stddev = 1.0) noexcept
+       : mean(mean)
+       , stddev(stddev)
+       { }
+
+public:
+       double Mean() const noexcept { return mean; }
+       double StandardDeviation() const noexcept { return stddev; }
+       double Variance() const noexcept { return stddev * stddev; }
+
+       /// convert uniform random value in [-1,1] to fake normal distribution
+       /// in [mean - 2 stdddev,mean + 2 stddev]
+       double FakeNormal(double uniform) const noexcept {
+               return mean + (uniform * uniform * stddev) + std::abs(uniform * uniform * uniform) * stddev;
+       }
+
+private:
+       double mean;
+       double stddev;
+
+};
+
+}
+}
+
+#endif