From 60b0d1d05dce6f953bd4585c4bac36ace5634c99 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Wed, 9 Dec 2020 08:20:11 +1000
Subject: [PATCH] geom/ellipse: prefer our normal distribution for sampling

The repeatability of a common implementation is relied upon by some
client libraries which must run under libstdc++ and libcxx
---
 geom/ellipse.hpp | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/geom/ellipse.hpp b/geom/ellipse.hpp
index 8ed89cc7..5437f802 100644
--- a/geom/ellipse.hpp
+++ b/geom/ellipse.hpp
@@ -14,8 +14,9 @@
 #include "../point.hpp"
 #include "../vector.hpp"
 
+#include <cruft/util/rand/distribution/normal.hpp>
+
 #include <cstdlib>
-#include <random>
 #include <iosfwd>
 
 
@@ -120,9 +121,9 @@ namespace cruft::geom {
         const auto c2 = c * c;
 
         // generate a direction vector from a normally distributed random variable
-        auto const x = std::normal_distribution<float> (0, a2) (generator);
-        auto const y = std::normal_distribution<float> (0, b2) (generator);
-        auto const z = std::normal_distribution<float> (0, c2) (generator);
+        auto const x = cruft::rand::distribution::normal<float> (0, a2) (generator);
+        auto const y = cruft::rand::distribution::normal<float> (0, b2) (generator);
+        auto const z = cruft::rand::distribution::normal<float> (0, c2) (generator);
 
         // find the distance to the surface along the direction vector
         auto const d = std::sqrt (x * x / a2 + y * y / b2 + z * z / c2);