Quick style fixes

Signed-off-by: Slendi <slendi@socopon.com>

.envrc

@@ -0,0 +1 @@
+use flake

.gitignore

@@ -1,3 +1,4 @@
 [Bb]uild*
 .cache
 result
+.direnv

flake.nix

@@ -1,8 +1,5 @@
-let
-  desc = "Single-file linear algebra math library for C++23.";
-in
 {
-  description = desc;
+  description = "Single-file linear algebra math library for C++23.";
 
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
@@ -50,17 +47,17 @@ in
                 prefix = "${placeholder "out"}";
                 includedir = "${prefix}/include";
               };
-              description = desc;
+              description = "Single-file linear algebra math library for C++23.";
             })
           ];
 
           dontBuild = true;
 
           installPhase = ''
-            						runHook preInstall
-                        mkdir -p $out/include
-                        cp include/*.hpp $out/include/
-            						runHook postInstall
+            runHook preInstall
+            mkdir -p $out/include
+            cp include/*.hpp $out/include/
+            runHook postInstall
           '';
 
           meta = with pkgs.lib; {

include/smath.hpp

@@ -25,8 +25,14 @@
 #include <cmath>
 #include <cstddef>
 #include <format>
+#include <numbers>
+#include <optional>
 #include <type_traits>
 
+#ifndef SMATH_ANGLE_UNIT
+#define SMATH_ANGLE_UNIT rad
+#endif // SMATH_ANGLE_UNIT
+
 namespace smath {
 
 template <std::size_t N, typename T>
@@ -35,6 +41,38 @@ struct Vec;
 
 namespace detail {
 
+#define SMATH_STR(x) #x
+#define SMATH_XSTR(x) SMATH_STR(x)
+
+consteval bool streq(const char *a, const char *b) {
+  for (;; ++a, ++b) {
+    if (*a != *b)
+      return false;
+    if (*a == '\0')
+      return true;
+  }
+}
+
+enum class AngularUnit {
+  Radians,
+  Degrees,
+  Turns,
+};
+
+consteval std::optional<AngularUnit> parse_unit(const char *s) {
+  if (streq(s, "rad"))
+    return AngularUnit::Radians;
+  if (streq(s, "deg"))
+    return AngularUnit::Degrees;
+  if (streq(s, "turns"))
+    return AngularUnit::Turns;
+  return std::nullopt;
+}
+
+constexpr auto SMATH_ANGLE_UNIT_ID = parse_unit(SMATH_XSTR(SMATH_ANGLE_UNIT));
+static_assert(SMATH_ANGLE_UNIT_ID != std::nullopt,
+              "Invalid SMATH_ANGLE_UNIT. Should be rad, deg, or turns.");
+
 template <std::size_t N> struct FixedString {
   char data[N]{};
   static constexpr std::size_t size = N - 1;
@@ -124,6 +162,14 @@ public:
   VEC_ACC(v, 2, 1)
 #undef VEC_ACC
 
+  // Unary
+  constexpr auto operator-() noexcept -> Vec {
+    Vec r{};
+    for (std::size_t i = 0; i < N; ++i)
+      r[i] = -(*this)[i];
+    return r;
+  }
+
   // RHS operations
   friend constexpr auto operator+(T s, Vec const &v) noexcept -> Vec {
     return v + s;
@@ -179,34 +225,60 @@ public:
   VEC_OP_ASSIGN(/)
 #undef VEC_OP_ASSIGN
 
-  constexpr auto magnitude() const noexcept -> T {
+  constexpr auto operator==(Vec const &v) const noexcept -> bool {
+    for (std::size_t i = 0; i < N; ++i)
+      if ((*this)[i] != v[i])
+        return false;
+    return true;
+  }
+
+  constexpr auto operator!=(Vec const &v) const noexcept -> bool {
+    return !(*this == v);
+  }
+
+  constexpr auto magnitude() const noexcept -> T
+    requires std::is_floating_point_v<T>
+  {
     T total = 0;
     for (auto const &v : *this)
       total += v * v;
     return std::sqrt(total);
   }
-  constexpr auto length() const noexcept -> T { return this->magnitude(); }
+  constexpr auto length() const noexcept -> T
+    requires std::is_floating_point_v<T>
+  {
+    return this->magnitude();
+  }
 
-  constexpr Vec normalized_safe(T eps = eps_default) const noexcept {
+  template <typename U = T>
+    requires std::is_floating_point_v<U>
+  constexpr auto normalized_safe(U eps = EPS_DEFAULT) const noexcept -> Vec {
     auto m = magnitude();
     return (m > eps) ? (*this) / m : Vec{};
   }
-  constexpr Vec normalize_safe(T eps = eps_default) const noexcept {
+  template <typename U = T>
+    requires std::is_floating_point_v<U>
+  constexpr auto normalize_safe(U eps = EPS_DEFAULT) const noexcept -> Vec {
     return normalized_safe(eps);
   }
 
-  [[nodiscard]] constexpr auto normalized() noexcept -> Vec<N, T> const {
+  [[nodiscard]] constexpr auto normalized() noexcept -> Vec<N, T>
+    requires std::is_floating_point_v<T>
+  {
     return (*this) / this->magnitude();
   }
-  [[nodiscard]] constexpr auto normalize() noexcept -> Vec<N, T> const {
+  [[nodiscard]] constexpr auto normalize() noexcept -> Vec<N, T>
+    requires std::is_floating_point_v<T>
+  {
     return this->normalized();
   }
-  [[nodiscard]] constexpr auto unit() noexcept -> Vec<N, T> const {
+  [[nodiscard]] constexpr auto unit() noexcept -> Vec<N, T>
+    requires std::is_floating_point_v<T>
+  {
     return this->normalized();
   }
 
-  [[nodiscard]] constexpr auto dot(Vec<N, T> const &other) const noexcept
-      -> T const {
+  [[nodiscard]] constexpr auto dot(Vec<N, T> const &other) const noexcept -> T {
     T res = 0;
     for (std::size_t i = 0; i < N; ++i) {
       res += (*this)[i] * other[i];
@@ -214,10 +286,11 @@ public:
     return res;
   }
 
-  static constexpr T eps_default = T(1e-6);
+  static constexpr T EPS_DEFAULT = T(1e-6);
   template <class U = T>
+    requires std::is_floating_point_v<U>
   [[nodiscard]] constexpr auto
-  approx_equal(Vec const &rhs, U eps = eps_default) const noexcept {
+  approx_equal(Vec const &rhs, U eps = EPS_DEFAULT) const noexcept {
     using F = std::conditional_t<std::is_floating_point_v<U>, U, double>;
     for (size_t i = 0; i < N; ++i)
       if (std::abs(F((*this)[i] - rhs[i])) > F(eps))
@@ -225,7 +298,10 @@ public:
     return true;
   }
 
-  template <class U = T> constexpr auto magnitude_promoted() const noexcept {
+  template <class U = T>
+  constexpr auto magnitude_promoted() const noexcept
+    requires std::is_floating_point_v<T>
+  {
     using F = std::conditional_t<std::is_floating_point_v<U>, U, double>;
     F s = 0;
     for (auto v : *this)
@@ -235,17 +311,21 @@ public:
 
   template <typename U = T>
     requires(N == 3)
-  constexpr Vec cross(const Vec &r) const noexcept {
+  constexpr auto cross(const Vec &r) const noexcept -> Vec {
     return {(*this)[1] * r[2] - (*this)[2] * r[1],
             (*this)[2] * r[0] - (*this)[0] * r[2],
             (*this)[0] * r[1] - (*this)[1] * r[0]};
   }
 
-  constexpr T distance(Vec const &r) const noexcept {
+  constexpr auto distance(Vec const &r) const noexcept -> T
+    requires std::is_floating_point_v<T>
+  {
     return (*this - r).magnitude();
   }
 
-  constexpr Vec project_onto(Vec const &n) const noexcept {
+  constexpr auto project_onto(Vec const &n) const noexcept -> Vec
+    requires std::is_floating_point_v<T>
+  {
     auto d = this->dot(n);
     auto nn = n.dot(n);
     return (nn ? (d / nn) * n : Vec());
@@ -271,7 +351,7 @@ public:
 
   template <class U>
     requires(std::is_arithmetic_v<U> && !std::is_same_v<U, T>)
-  constexpr Vec &operator=(Vec<N, U> const &rhs) noexcept {
+  constexpr auto operator=(Vec<N, U> const &rhs) noexcept -> Vec & {
     for (std::size_t i = 0; i < N; ++i)
       (*this)[i] = static_cast<T>(rhs[i]);
     return *this;
@@ -401,6 +481,42 @@ using Vec2d = Vec<2, double>;
 using Vec3d = Vec<3, double>;
 using Vec4d = Vec<4, double>;
 
+template <class T> constexpr auto deg(T const value) -> T {
+  if constexpr (detail::SMATH_ANGLE_UNIT_ID == detail::AngularUnit::Degrees) {
+    return value;
+  } else if constexpr (detail::SMATH_ANGLE_UNIT_ID ==
+                       detail::AngularUnit::Radians) {
+    return value * static_cast<T>(std::numbers::pi / 180.0);
+  } else if constexpr (detail::SMATH_ANGLE_UNIT_ID ==
+                       detail::AngularUnit::Turns) {
+    return value / static_cast<T>(360.0);
+  }
+}
+
+template <class T> constexpr auto rad(T const value) -> T {
+  if constexpr (detail::SMATH_ANGLE_UNIT_ID == detail::AngularUnit::Degrees) {
+    return value * static_cast<T>(180.0 / std::numbers::pi);
+  } else if constexpr (detail::SMATH_ANGLE_UNIT_ID ==
+                       detail::AngularUnit::Radians) {
+    return value;
+  } else if constexpr (detail::SMATH_ANGLE_UNIT_ID ==
+                       detail::AngularUnit::Turns) {
+    return value / (static_cast<T>(2.0) * static_cast<T>(std::numbers::pi));
+  }
+}
+
+template <class T> constexpr auto turns(T const value) -> T {
+  if constexpr (detail::SMATH_ANGLE_UNIT_ID == detail::AngularUnit::Degrees) {
+    return value * static_cast<T>(360.0);
+  } else if constexpr (detail::SMATH_ANGLE_UNIT_ID ==
+                       detail::AngularUnit::Radians) {
+    return value * (static_cast<T>(2.0) * static_cast<T>(std::numbers::pi));
+  } else if constexpr (detail::SMATH_ANGLE_UNIT_ID ==
+                       detail::AngularUnit::Turns) {
+    return value;
+  }
+}
+
 } // namespace smath
 
 template <std::size_t N, typename T>
@@ -435,4 +551,5 @@ struct tuple_element<I, smath::Vec<N, T>> {
   static_assert(I < N);
   using type = T;
 };
+
 } // namespace std

tests/angles.cpp

@@ -0,0 +1,15 @@
+#include <gtest/gtest.h>
+
+#include <smath.hpp>
+
+TEST(AngleReturnRadians, DegInput) {
+  EXPECT_NEAR(smath::deg(180.0), std::numbers::pi, 1e-12);
+}
+
+TEST(AngleReturnRadians, RadInput) {
+  EXPECT_DOUBLE_EQ(smath::rad(std::numbers::pi), std::numbers::pi);
+}
+
+TEST(AngleReturnRadians, TurnsInput) {
+  EXPECT_NEAR(smath::turns(0.5), std::numbers::pi, 1e-12);
+}