From 5c323d96e034c49e60dccb966a1ab753239b1ce6 Mon Sep 17 00:00:00 2001
From: Lioncash <mathew1800@gmail.com>
Date: Tue, 7 Aug 2018 21:32:05 -0400
Subject: vector_math: Make functions constexpr where applicable

---
 src/common/vector_math.h | 333 +++++++++++++++++++++++++----------------------
 1 file changed, 179 insertions(+), 154 deletions(-)

(limited to 'src/common/vector_math.h')

diff --git a/src/common/vector_math.h b/src/common/vector_math.h
index 108399ae82..7e5af651a3 100644
--- a/src/common/vector_math.h
+++ b/src/common/vector_math.h
@@ -42,71 +42,72 @@ class Vec3;
 template <typename T>
 class Vec4;
 
-template <typename T>
-static inline Vec2<T> MakeVec(const T& x, const T& y);
-template <typename T>
-static inline Vec3<T> MakeVec(const T& x, const T& y, const T& z);
-template <typename T>
-static inline Vec4<T> MakeVec(const T& x, const T& y, const T& z, const T& w);
-
 template <typename T>
 class Vec2 {
 public:
     T x{};
     T y{};
 
-    Vec2() = default;
-    Vec2(const T& _x, const T& _y) : x(_x), y(_y) {}
+    constexpr Vec2() = default;
+    constexpr Vec2(const T& x_, const T& y_) : x(x_), y(y_) {}
 
     template <typename T2>
-    Vec2<T2> Cast() const {
-        return Vec2<T2>((T2)x, (T2)y);
+    constexpr Vec2<T2> Cast() const {
+        return Vec2<T2>(static_cast<T2>(x), static_cast<T2>(y));
     }
 
-    static Vec2 AssignToAll(const T& f) {
-        return Vec2<T>(f, f);
+    static constexpr Vec2 AssignToAll(const T& f) {
+        return Vec2{f, f};
     }
 
-    Vec2<decltype(T{} + T{})> operator+(const Vec2& other) const {
-        return MakeVec(x + other.x, y + other.y);
+    constexpr Vec2<decltype(T{} + T{})> operator+(const Vec2& other) const {
+        return {x + other.x, y + other.y};
     }
-    void operator+=(const Vec2& other) {
+    constexpr Vec2& operator+=(const Vec2& other) {
         x += other.x;
         y += other.y;
+        return *this;
     }
-    Vec2<decltype(T{} - T{})> operator-(const Vec2& other) const {
-        return MakeVec(x - other.x, y - other.y);
+    constexpr Vec2<decltype(T{} - T{})> operator-(const Vec2& other) const {
+        return {x - other.x, y - other.y};
     }
-    void operator-=(const Vec2& other) {
+    constexpr Vec2& operator-=(const Vec2& other) {
         x -= other.x;
         y -= other.y;
+        return *this;
     }
 
     template <typename U = T>
-    Vec2<std::enable_if_t<std::is_signed<U>::value, U>> operator-() const {
-        return MakeVec(-x, -y);
+    constexpr Vec2<std::enable_if_t<std::is_signed<U>::value, U>> operator-() const {
+        return {-x, -y};
     }
-    Vec2<decltype(T{} * T{})> operator*(const Vec2& other) const {
-        return MakeVec(x * other.x, y * other.y);
+    constexpr Vec2<decltype(T{} * T{})> operator*(const Vec2& other) const {
+        return {x * other.x, y * other.y};
     }
+
     template <typename V>
-    Vec2<decltype(T{} * V{})> operator*(const V& f) const {
-        return MakeVec(x * f, y * f);
+    constexpr Vec2<decltype(T{} * V{})> operator*(const V& f) const {
+        return {x * f, y * f};
     }
+
     template <typename V>
-    void operator*=(const V& f) {
+    constexpr Vec2& operator*=(const V& f) {
         *this = *this * f;
+        return *this;
     }
+
     template <typename V>
-    Vec2<decltype(T{} / V{})> operator/(const V& f) const {
-        return MakeVec(x / f, y / f);
+    constexpr Vec2<decltype(T{} / V{})> operator/(const V& f) const {
+        return {x / f, y / f};
     }
+
     template <typename V>
-    void operator/=(const V& f) {
+    constexpr Vec2& operator/=(const V& f) {
         *this = *this / f;
+        return *this;
     }
 
-    T Length2() const {
+    constexpr T Length2() const {
         return x * x + y * y;
     }
 
@@ -118,60 +119,59 @@ public:
     Vec2 Normalized() const;
     float Normalize(); // returns the previous length, which is often useful
 
-    T& operator[](int i) // allow vector[1] = 3   (vector.y=3)
-    {
+    constexpr T& operator[](std::size_t i) {
         return *((&x) + i);
     }
-    T operator[](const int i) const {
+    constexpr const T& operator[](std::size_t i) const {
         return *((&x) + i);
     }
 
-    void SetZero() {
+    constexpr void SetZero() {
         x = 0;
         y = 0;
     }
 
     // Common aliases: UV (texel coordinates), ST (texture coordinates)
-    T& u() {
+    constexpr T& u() {
         return x;
     }
-    T& v() {
+    constexpr T& v() {
         return y;
     }
-    T& s() {
+    constexpr T& s() {
         return x;
     }
-    T& t() {
+    constexpr T& t() {
         return y;
     }
 
-    const T& u() const {
+    constexpr const T& u() const {
         return x;
     }
-    const T& v() const {
+    constexpr const T& v() const {
         return y;
     }
-    const T& s() const {
+    constexpr const T& s() const {
         return x;
     }
-    const T& t() const {
+    constexpr const T& t() const {
         return y;
     }
 
     // swizzlers - create a subvector of specific components
-    const Vec2 yx() const {
+    constexpr Vec2 yx() const {
         return Vec2(y, x);
     }
-    const Vec2 vu() const {
+    constexpr Vec2 vu() const {
         return Vec2(y, x);
     }
-    const Vec2 ts() const {
+    constexpr Vec2 ts() const {
         return Vec2(y, x);
     }
 };
 
 template <typename T, typename V>
-Vec2<T> operator*(const V& f, const Vec2<T>& vec) {
+constexpr Vec2<T> operator*(const V& f, const Vec2<T>& vec) {
     return Vec2<T>(f * vec.x, f * vec.y);
 }
 
@@ -196,64 +196,75 @@ public:
     T y{};
     T z{};
 
-    Vec3() = default;
-    Vec3(const T& _x, const T& _y, const T& _z) : x(_x), y(_y), z(_z) {}
+    constexpr Vec3() = default;
+    constexpr Vec3(const T& x_, const T& y_, const T& z_) : x(x_), y(y_), z(z_) {}
 
     template <typename T2>
-    Vec3<T2> Cast() const {
-        return MakeVec<T2>((T2)x, (T2)y, (T2)z);
+    constexpr Vec3<T2> Cast() const {
+        return Vec3<T2>(static_cast<T2>(x), static_cast<T2>(y), static_cast<T2>(z));
     }
 
     // Only implemented for T=int and T=float
     static Vec3 FromRGB(unsigned int rgb);
     unsigned int ToRGB() const; // alpha bits set to zero
 
-    static Vec3 AssignToAll(const T& f) {
-        return MakeVec(f, f, f);
+    static constexpr Vec3 AssignToAll(const T& f) {
+        return Vec3(f, f, f);
     }
 
-    Vec3<decltype(T{} + T{})> operator+(const Vec3& other) const {
-        return MakeVec(x + other.x, y + other.y, z + other.z);
+    constexpr Vec3<decltype(T{} + T{})> operator+(const Vec3& other) const {
+        return {x + other.x, y + other.y, z + other.z};
     }
-    void operator+=(const Vec3& other) {
+
+    constexpr Vec3& operator+=(const Vec3& other) {
         x += other.x;
         y += other.y;
         z += other.z;
+        return *this;
     }
-    Vec3<decltype(T{} - T{})> operator-(const Vec3& other) const {
-        return MakeVec(x - other.x, y - other.y, z - other.z);
+
+    constexpr Vec3<decltype(T{} - T{})> operator-(const Vec3& other) const {
+        return {x - other.x, y - other.y, z - other.z};
     }
-    void operator-=(const Vec3& other) {
+
+    constexpr Vec3& operator-=(const Vec3& other) {
         x -= other.x;
         y -= other.y;
         z -= other.z;
+        return *this;
     }
 
     template <typename U = T>
-    Vec3<std::enable_if_t<std::is_signed<U>::value, U>> operator-() const {
-        return MakeVec(-x, -y, -z);
+    constexpr Vec3<std::enable_if_t<std::is_signed<U>::value, U>> operator-() const {
+        return {-x, -y, -z};
     }
-    Vec3<decltype(T{} * T{})> operator*(const Vec3& other) const {
-        return MakeVec(x * other.x, y * other.y, z * other.z);
+
+    constexpr Vec3<decltype(T{} * T{})> operator*(const Vec3& other) const {
+        return {x * other.x, y * other.y, z * other.z};
     }
+
     template <typename V>
-    Vec3<decltype(T{} * V{})> operator*(const V& f) const {
-        return MakeVec(x * f, y * f, z * f);
+    constexpr Vec3<decltype(T{} * V{})> operator*(const V& f) const {
+        return {x * f, y * f, z * f};
     }
+
     template <typename V>
-    void operator*=(const V& f) {
+    constexpr Vec3& operator*=(const V& f) {
         *this = *this * f;
+        return *this;
     }
     template <typename V>
-    Vec3<decltype(T{} / V{})> operator/(const V& f) const {
-        return MakeVec(x / f, y / f, z / f);
+    constexpr Vec3<decltype(T{} / V{})> operator/(const V& f) const {
+        return {x / f, y / f, z / f};
     }
+
     template <typename V>
-    void operator/=(const V& f) {
+    constexpr Vec3& operator/=(const V& f) {
         *this = *this / f;
+        return *this;
     }
 
-    T Length2() const {
+    constexpr T Length2() const {
         return x * x + y * y + z * z;
     }
 
@@ -265,78 +276,78 @@ public:
     Vec3 Normalized() const;
     float Normalize(); // returns the previous length, which is often useful
 
-    T& operator[](int i) // allow vector[2] = 3   (vector.z=3)
-    {
+    constexpr T& operator[](std::size_t i) {
         return *((&x) + i);
     }
-    T operator[](const int i) const {
+
+    constexpr const T& operator[](std::size_t i) const {
         return *((&x) + i);
     }
 
-    void SetZero() {
+    constexpr void SetZero() {
         x = 0;
         y = 0;
         z = 0;
     }
 
     // Common aliases: UVW (texel coordinates), RGB (colors), STQ (texture coordinates)
-    T& u() {
+    constexpr T& u() {
         return x;
     }
-    T& v() {
+    constexpr T& v() {
         return y;
     }
-    T& w() {
+    constexpr T& w() {
         return z;
     }
 
-    T& r() {
+    constexpr T& r() {
         return x;
     }
-    T& g() {
+    constexpr T& g() {
         return y;
     }
-    T& b() {
+    constexpr T& b() {
         return z;
     }
 
-    T& s() {
+    constexpr T& s() {
         return x;
     }
-    T& t() {
+    constexpr T& t() {
         return y;
     }
-    T& q() {
+    constexpr T& q() {
         return z;
     }
 
-    const T& u() const {
+    constexpr const T& u() const {
         return x;
     }
-    const T& v() const {
+    constexpr const T& v() const {
         return y;
     }
-    const T& w() const {
+    constexpr const T& w() const {
         return z;
     }
 
-    const T& r() const {
+    constexpr const T& r() const {
         return x;
     }
-    const T& g() const {
+    constexpr const T& g() const {
         return y;
     }
-    const T& b() const {
+    constexpr const T& b() const {
         return z;
     }
 
-    const T& s() const {
+    constexpr const T& s() const {
         return x;
     }
-    const T& t() const {
+    constexpr const T& t() const {
         return y;
     }
-    const T& q() const {
+    constexpr const T& q() const {
         return z;
     }
 
@@ -345,7 +356,7 @@ public:
 // _DEFINE_SWIZZLER2 defines a single such function, DEFINE_SWIZZLER2 defines all of them for all
 // component names (x<->r) and permutations (xy<->yx)
 #define _DEFINE_SWIZZLER2(a, b, name)                                                              \
-    const Vec2<T> name() const {                                                                   \
+    constexpr Vec2<T> name() const {                                                               \
         return Vec2<T>(a, b);                                                                      \
     }
 #define DEFINE_SWIZZLER2(a, b, a2, b2, a3, b3, a4, b4)                                             \
@@ -366,7 +377,7 @@ public:
 };
 
 template <typename T, typename V>
-Vec3<T> operator*(const V& f, const Vec3<T>& vec) {
+constexpr Vec3<T> operator*(const V& f, const Vec3<T>& vec) {
     return Vec3<T>(f * vec.x, f * vec.y, f * vec.z);
 }
 
@@ -397,66 +408,80 @@ public:
     T z{};
     T w{};
 
-    Vec4() = default;
-    Vec4(const T& _x, const T& _y, const T& _z, const T& _w) : x(_x), y(_y), z(_z), w(_w) {}
+    constexpr Vec4() = default;
+    constexpr Vec4(const T& x_, const T& y_, const T& z_, const T& w_)
+        : x(x_), y(y_), z(z_), w(w_) {}
 
     template <typename T2>
-    Vec4<T2> Cast() const {
-        return Vec4<T2>((T2)x, (T2)y, (T2)z, (T2)w);
+    constexpr Vec4<T2> Cast() const {
+        return Vec4<T2>(static_cast<T2>(x), static_cast<T2>(y), static_cast<T2>(z),
+                        static_cast<T2>(w));
     }
 
     // Only implemented for T=int and T=float
     static Vec4 FromRGBA(unsigned int rgba);
     unsigned int ToRGBA() const;
 
-    static Vec4 AssignToAll(const T& f) {
-        return Vec4<T>(f, f, f, f);
+    static constexpr Vec4 AssignToAll(const T& f) {
+        return Vec4(f, f, f, f);
     }
 
-    Vec4<decltype(T{} + T{})> operator+(const Vec4& other) const {
-        return MakeVec(x + other.x, y + other.y, z + other.z, w + other.w);
+    constexpr Vec4<decltype(T{} + T{})> operator+(const Vec4& other) const {
+        return {x + other.x, y + other.y, z + other.z, w + other.w};
     }
-    void operator+=(const Vec4& other) {
+
+    constexpr Vec4& operator+=(const Vec4& other) {
         x += other.x;
         y += other.y;
         z += other.z;
         w += other.w;
+        return *this;
     }
-    Vec4<decltype(T{} - T{})> operator-(const Vec4& other) const {
-        return MakeVec(x - other.x, y - other.y, z - other.z, w - other.w);
+
+    constexpr Vec4<decltype(T{} - T{})> operator-(const Vec4& other) const {
+        return {x - other.x, y - other.y, z - other.z, w - other.w};
     }
-    void operator-=(const Vec4& other) {
+
+    constexpr Vec4& operator-=(const Vec4& other) {
         x -= other.x;
         y -= other.y;
         z -= other.z;
         w -= other.w;
+        return *this;
     }
 
     template <typename U = T>
-    Vec4<std::enable_if_t<std::is_signed<U>::value, U>> operator-() const {
-        return MakeVec(-x, -y, -z, -w);
+    constexpr Vec4<std::enable_if_t<std::is_signed<U>::value, U>> operator-() const {
+        return {-x, -y, -z, -w};
     }
-    Vec4<decltype(T{} * T{})> operator*(const Vec4& other) const {
-        return MakeVec(x * other.x, y * other.y, z * other.z, w * other.w);
+
+    constexpr Vec4<decltype(T{} * T{})> operator*(const Vec4& other) const {
+        return {x * other.x, y * other.y, z * other.z, w * other.w};
     }
+
     template <typename V>
-    Vec4<decltype(T{} * V{})> operator*(const V& f) const {
-        return MakeVec(x * f, y * f, z * f, w * f);
+    constexpr Vec4<decltype(T{} * V{})> operator*(const V& f) const {
+        return {x * f, y * f, z * f, w * f};
     }
+
     template <typename V>
-    void operator*=(const V& f) {
+    constexpr Vec4& operator*=(const V& f) {
         *this = *this * f;
+        return *this;
     }
+
     template <typename V>
-    Vec4<decltype(T{} / V{})> operator/(const V& f) const {
-        return MakeVec(x / f, y / f, z / f, w / f);
+    constexpr Vec4<decltype(T{} / V{})> operator/(const V& f) const {
+        return {x / f, y / f, z / f, w / f};
     }
+
     template <typename V>
-    void operator/=(const V& f) {
+    constexpr Vec4& operator/=(const V& f) {
         *this = *this / f;
+        return *this;
     }
 
-    T Length2() const {
+    constexpr T Length2() const {
         return x * x + y * y + z * z + w * w;
     }
 
@@ -468,15 +493,15 @@ public:
     Vec4 Normalized() const;
     float Normalize(); // returns the previous length, which is often useful
 
-    T& operator[](int i) // allow vector[2] = 3   (vector.z=3)
-    {
+    constexpr T& operator[](std::size_t i) {
         return *((&x) + i);
     }
-    T operator[](const int i) const {
+
+    constexpr const T& operator[](std::size_t i) const {
         return *((&x) + i);
     }
 
-    void SetZero() {
+    constexpr void SetZero() {
         x = 0;
         y = 0;
         z = 0;
@@ -484,29 +509,29 @@ public:
     }
 
     // Common alias: RGBA (colors)
-    T& r() {
+    constexpr T& r() {
         return x;
     }
-    T& g() {
+    constexpr T& g() {
         return y;
     }
-    T& b() {
+    constexpr T& b() {
         return z;
     }
-    T& a() {
+    constexpr T& a() {
         return w;
     }
 
-    const T& r() const {
+    constexpr const T& r() const {
         return x;
     }
-    const T& g() const {
+    constexpr const T& g() const {
         return y;
     }
-    const T& b() const {
+    constexpr const T& b() const {
         return z;
     }
-    const T& a() const {
+    constexpr const T& a() const {
         return w;
     }
 
@@ -518,7 +543,7 @@ public:
 // DEFINE_SWIZZLER2_COMP2 defines two component functions for all component names (x<->r) and
 // permutations (xy<->yx)
 #define _DEFINE_SWIZZLER2(a, b, name)                                                              \
-    const Vec2<T> name() const {                                                                   \
+    constexpr Vec2<T> name() const {                                                               \
         return Vec2<T>(a, b);                                                                      \
     }
 #define DEFINE_SWIZZLER2_COMP1(a, a2)                                                              \
@@ -545,7 +570,7 @@ public:
 #undef _DEFINE_SWIZZLER2
 
 #define _DEFINE_SWIZZLER3(a, b, c, name)                                                           \
-    const Vec3<T> name() const {                                                                   \
+    constexpr Vec3<T> name() const {                                                               \
         return Vec3<T>(a, b, c);                                                                   \
     }
 #define DEFINE_SWIZZLER3_COMP1(a, a2)                                                              \
@@ -579,51 +604,51 @@ public:
 };
 
 template <typename T, typename V>
-Vec4<decltype(V{} * T{})> operator*(const V& f, const Vec4<T>& vec) {
-    return MakeVec(f * vec.x, f * vec.y, f * vec.z, f * vec.w);
+constexpr Vec4<decltype(V{} * T{})> operator*(const V& f, const Vec4<T>& vec) {
+    return {f * vec.x, f * vec.y, f * vec.z, f * vec.w};
 }
 
 using Vec4f = Vec4<float>;
 
 template <typename T>
-static inline decltype(T{} * T{} + T{} * T{}) Dot(const Vec2<T>& a, const Vec2<T>& b) {
+constexpr decltype(T{} * T{} + T{} * T{}) Dot(const Vec2<T>& a, const Vec2<T>& b) {
     return a.x * b.x + a.y * b.y;
 }
 
 template <typename T>
-static inline decltype(T{} * T{} + T{} * T{}) Dot(const Vec3<T>& a, const Vec3<T>& b) {
+constexpr decltype(T{} * T{} + T{} * T{}) Dot(const Vec3<T>& a, const Vec3<T>& b) {
     return a.x * b.x + a.y * b.y + a.z * b.z;
 }
 
 template <typename T>
-static inline decltype(T{} * T{} + T{} * T{}) Dot(const Vec4<T>& a, const Vec4<T>& b) {
+constexpr decltype(T{} * T{} + T{} * T{}) Dot(const Vec4<T>& a, const Vec4<T>& b) {
     return a.x * b.x + a.y * b.y + a.z * b.z + a.w * b.w;
 }
 
 template <typename T>
-static inline Vec3<decltype(T{} * T{} - T{} * T{})> Cross(const Vec3<T>& a, const Vec3<T>& b) {
-    return MakeVec(a.y * b.z - a.z * b.y, a.z * b.x - a.x * b.z, a.x * b.y - a.y * b.x);
+constexpr Vec3<decltype(T{} * T{} - T{} * T{})> Cross(const Vec3<T>& a, const Vec3<T>& b) {
+    return {a.y * b.z - a.z * b.y, a.z * b.x - a.x * b.z, a.x * b.y - a.y * b.x};
 }
 
 // linear interpolation via float: 0.0=begin, 1.0=end
 template <typename X>
-static inline decltype(X{} * float{} + X{} * float{}) Lerp(const X& begin, const X& end,
-                                                           const float t) {
+constexpr decltype(X{} * float{} + X{} * float{}) Lerp(const X& begin, const X& end,
+                                                       const float t) {
     return begin * (1.f - t) + end * t;
 }
 
 // linear interpolation via int: 0=begin, base=end
 template <typename X, int base>
-static inline decltype((X{} * int{} + X{} * int{}) / base) LerpInt(const X& begin, const X& end,
-                                                                   const int t) {
+constexpr decltype((X{} * int{} + X{} * int{}) / base) LerpInt(const X& begin, const X& end,
+                                                               const int t) {
     return (begin * (base - t) + end * t) / base;
 }
 
 // bilinear interpolation. s is for interpolating x00-x01 and x10-x11, and t is for the second
 // interpolation.
 template <typename X>
-inline auto BilinearInterp(const X& x00, const X& x01, const X& x10, const X& x11, const float s,
-                           const float t) {
+constexpr auto BilinearInterp(const X& x00, const X& x01, const X& x10, const X& x11, const float s,
+                              const float t) {
     auto y0 = Lerp(x00, x01, s);
     auto y1 = Lerp(x10, x11, s);
     return Lerp(y0, y1, t);
@@ -631,42 +656,42 @@ inline auto BilinearInterp(const X& x00, const X& x01, const X& x10, const X& x1
 
 // Utility vector factories
 template <typename T>
-static inline Vec2<T> MakeVec(const T& x, const T& y) {
+constexpr Vec2<T> MakeVec(const T& x, const T& y) {
     return Vec2<T>{x, y};
 }
 
 template <typename T>
-static inline Vec3<T> MakeVec(const T& x, const T& y, const T& z) {
+constexpr Vec3<T> MakeVec(const T& x, const T& y, const T& z) {
     return Vec3<T>{x, y, z};
 }
 
 template <typename T>
-static inline Vec4<T> MakeVec(const T& x, const T& y, const Vec2<T>& zw) {
+constexpr Vec4<T> MakeVec(const T& x, const T& y, const Vec2<T>& zw) {
     return MakeVec(x, y, zw[0], zw[1]);
 }
 
 template <typename T>
-static inline Vec3<T> MakeVec(const Vec2<T>& xy, const T& z) {
+constexpr Vec3<T> MakeVec(const Vec2<T>& xy, const T& z) {
     return MakeVec(xy[0], xy[1], z);
 }
 
 template <typename T>
-static inline Vec3<T> MakeVec(const T& x, const Vec2<T>& yz) {
+constexpr Vec3<T> MakeVec(const T& x, const Vec2<T>& yz) {
     return MakeVec(x, yz[0], yz[1]);
 }
 
 template <typename T>
-static inline Vec4<T> MakeVec(const T& x, const T& y, const T& z, const T& w) {
+constexpr Vec4<T> MakeVec(const T& x, const T& y, const T& z, const T& w) {
     return Vec4<T>{x, y, z, w};
 }
 
 template <typename T>
-static inline Vec4<T> MakeVec(const Vec2<T>& xy, const T& z, const T& w) {
+constexpr Vec4<T> MakeVec(const Vec2<T>& xy, const T& z, const T& w) {
     return MakeVec(xy[0], xy[1], z, w);
 }
 
 template <typename T>
-static inline Vec4<T> MakeVec(const T& x, const Vec2<T>& yz, const T& w) {
+constexpr Vec4<T> MakeVec(const T& x, const Vec2<T>& yz, const T& w) {
     return MakeVec(x, yz[0], yz[1], w);
 }
 
@@ -674,17 +699,17 @@ static inline Vec4<T> MakeVec(const T& x, const Vec2<T>& yz, const T& w) {
 //       Even if someone wanted to use an odd object like Vec2<Vec2<T>>, the compiler would error
 //       out soon enough due to misuse of the returned structure.
 template <typename T>
-static inline Vec4<T> MakeVec(const Vec2<T>& xy, const Vec2<T>& zw) {
+constexpr Vec4<T> MakeVec(const Vec2<T>& xy, const Vec2<T>& zw) {
     return MakeVec(xy[0], xy[1], zw[0], zw[1]);
 }
 
 template <typename T>
-static inline Vec4<T> MakeVec(const Vec3<T>& xyz, const T& w) {
+constexpr Vec4<T> MakeVec(const Vec3<T>& xyz, const T& w) {
     return MakeVec(xyz[0], xyz[1], xyz[2], w);
 }
 
 template <typename T>
-static inline Vec4<T> MakeVec(const T& x, const Vec3<T>& yzw) {
+constexpr Vec4<T> MakeVec(const T& x, const Vec3<T>& yzw) {
     return MakeVec(x, yzw[0], yzw[1], yzw[2]);
 }
 
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