From 294d9eb9b312eeabde6865a50141e7e28256a911 Mon Sep 17 00:00:00 2001
From: Nao Pross <naopross@thearcway.org>
Date: Mon, 10 Dec 2018 14:33:40 +0100
Subject: Implement cross product for vec2 and vec3

---
 vector/vector.cpp | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/vector/vector.cpp b/vector/vector.cpp
index 0322ee2..9e0ca6c 100644
--- a/vector/vector.cpp
+++ b/vector/vector.cpp
@@ -1,19 +1,18 @@
 #include <iostream>
 
+#include <iterator>
 #include <cassert>
 #include <array>
 #include <initializer_list>
 #include <algorithm>
 
 template<typename T, std::size_t d>
-class basic_vec : public std::array<T, d> {
-public:
+struct basic_vec : public std::array<T, d> {
     static constexpr std::size_t dimensions = d;
 
     basic_vec();
-    basic_vec(std::initializer_list<T> l);
-    template<std::size_t n>
-    basic_vec(const basic_vec<T, n>& other);
+    basic_vec(const std::initializer_list<T> l);
+    template<std::size_t n> basic_vec(const basic_vec<T, n>& other);
 
     T length() const;
 };
@@ -24,17 +23,20 @@ basic_vec<T, d>::basic_vec() : std::array<T, d>() {
 }
 
 template<typename T, std::size_t d>
-basic_vec<T, d>::basic_vec(std::initializer_list<T> l) {
+basic_vec<T, d>::basic_vec(const std::initializer_list<T> l) {
+    basic_vec();
+
+    // why can't this sh*t be a constexpr with static_assert???
     assert(l.size() <= d);
-    this->fill(static_cast<T>(0));
     std::copy(l.begin(), l.end(), this->begin());
 }
 
 template<typename T, std::size_t d>
 template<std::size_t n>
 basic_vec<T, d>::basic_vec(const basic_vec<T, n>& other) {
+    basic_vec();
+
     static_assert(d >= n);
-    this->fill(static_cast<T>(0));
     for (std::size_t i = 0;  i < n; i++) {
         this->at(i) = other.at(i);
     }
@@ -122,7 +124,10 @@ public:
 template<typename T>
 vec3<T> vec3<T>::cross(const vec3<T>& rhs, const vec3<T>& lhs) {
     vec3<T> res;
-    // TODO: cross product
+
+    res[0] = (rhs[1] * lhs[2]) - (rhs[2] * lhs[1]);
+    res[1] = (rhs[2] * lhs[0]) - (rhs[0] * lhs[2]);
+    res[2] = (rhs[0] * lhs[1]) - (rhs[1] * lhs[0]);
 
     return res;
 }
@@ -142,8 +147,7 @@ public:
 
 template<typename T>
 vec3<T> vec2<T>::cross(const vec2<T>& rhs, const vec2<T>& lhs) {
-    vec3<T> res;
-    // TODO: cross product
+    return vec3<T>::cross(vec3<T>(rhs), vec3<T>(lhs));
 }
 
 
-- 
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