From aaaebdc042324f30b49b2077a63126214b8b2a30 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9ophile=20Bastian?= <contact@tobast.fr>
Date: Tue, 13 Feb 2018 16:14:28 +0100
Subject: [PATCH] Normalize normals to norm 1

---
 Implicit.cpp          | 10 ++++++----
 Mesh.cpp              |  2 +-
 common_structures.hpp | 11 +++++++++++
 3 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/Implicit.cpp b/Implicit.cpp
index 2ab78eb..c14422b 100644
--- a/Implicit.cpp
+++ b/Implicit.cpp
@@ -8,11 +8,13 @@ Point ImplicitSurface::normal_at(const Point& pt) const {
     // this is simply the gradient.
     static const double d_dist = 1e-8;
 
-    return Point(
+    Point normal(
             (operator()(pt.x + d_dist, pt.y, pt.z) -
-                operator()(pt.x - d_dist, pt.y, pt.z)) / (2. * d_dist),
+             operator()(pt.x - d_dist, pt.y, pt.z)) / (2. * d_dist),
             (operator()(pt.x, pt.y + d_dist, pt.z) -
-                operator()(pt.x, pt.y - d_dist, pt.z)) / (2. * d_dist),
+             operator()(pt.x, pt.y - d_dist, pt.z)) / (2. * d_dist),
             (operator()(pt.x, pt.y, pt.z + d_dist) -
-                operator()(pt.x, pt.y, pt.z - d_dist)) / (2. * d_dist));
+             operator()(pt.x, pt.y, pt.z - d_dist)) / (2. * d_dist));
+    normal.normalize();
+    return normal;
 }
diff --git a/Mesh.cpp b/Mesh.cpp
index a0b4a24..b805de3 100644
--- a/Mesh.cpp
+++ b/Mesh.cpp
@@ -91,7 +91,7 @@ void Mesh::compute_normal(size_t vert) {
         normal += e1.cross_prod(e2);
     }
 
-    normal = (1. / ((double) faces_with_vert[vert].size())) * normal;
+    normal.normalize();
     normals[vert].dirty = false;
     normals[vert].vect = normal;
 }
diff --git a/common_structures.hpp b/common_structures.hpp
index df3453a..2b5f4b0 100644
--- a/common_structures.hpp
+++ b/common_structures.hpp
@@ -13,6 +13,17 @@ struct Point {
     Point(double x, double y, double z) : x(x), y(y), z(z) {}
     double x, y, z;
 
+    double norm() const {
+        auto sq = [](double x) { return x * x; };
+        return sqrt(sq(x) + sq(y) + sq(z));
+    }
+    void normalize() {
+        double _norm = norm();
+        x /= _norm;
+        y /= _norm;
+        z /= _norm;
+    }
+
     double operator[](unsigned i) const {
         assert(i < 3);
         switch(i) {