From 9e0b61f30d995a7c5f5640039aeb8fb502b0629f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Leclercq?=
 <jerome.leclercq@fullcycle.games>
Date: Wed, 5 Sep 2018 15:14:31 +0200
Subject: [PATCH] Math/Angle: Add sine, cosine, tangent methods

---
 include/Nazara/Math/Angle.hpp |  6 +++
 include/Nazara/Math/Angle.inl | 78 +++++++++++++++++++++++++++++++++--
 tests/Engine/Math/Angle.cpp   | 47 +++++++++++++++++++--
 3 files changed, 125 insertions(+), 6 deletions(-)

diff --git a/include/Nazara/Math/Angle.hpp b/include/Nazara/Math/Angle.hpp
index ccf770959..e1c904204 100644
--- a/include/Nazara/Math/Angle.hpp
+++ b/include/Nazara/Math/Angle.hpp
@@ -11,6 +11,7 @@
 #include <Nazara/Math/Algorithm.hpp>
 #include <Nazara/Math/Enums.hpp>
 #include <type_traits>
+#include <utility>
 
 namespace Nz
 {
@@ -28,6 +29,11 @@ namespace Nz
 			Angle(const Angle&) = default;
 			~Angle() = default;
 
+			T GetCos() const;
+			T GetSin() const;
+			std::pair<T, T> GetSinCos() const;
+			T GetTan() const;
+
 			Angle& MakeZero();
 
 			void Normalize();
diff --git a/include/Nazara/Math/Angle.inl b/include/Nazara/Math/Angle.inl
index 0e8f8dbfe..e04a751d9 100644
--- a/include/Nazara/Math/Angle.inl
+++ b/include/Nazara/Math/Angle.inl
@@ -16,6 +16,11 @@ namespace Nz
 		template<>
 		struct AngleUtils<AngleUnit::Degree>
 		{
+			template<typename T> static constexpr T GetEpsilon()
+			{
+				return T(1e-4);
+			}
+
 			template<typename T> static constexpr T GetLimit()
 			{
 				return 180;
@@ -55,9 +60,14 @@ namespace Nz
 		template<>
 		struct AngleUtils<AngleUnit::Radian>
 		{
+			template<typename T> static constexpr T GetEpsilon()
+			{
+				return T(1e-5);
+			}
+
 			template<typename T> static constexpr T GetLimit()
 			{
-				return M_PI;
+				return T(M_PI);
 			}
 
 			template<typename T> static T FromDegrees(T degrees)
@@ -90,6 +100,14 @@ namespace Nz
 				return out << "Angle(" << value << "rad)";
 			}
 		};
+
+		// Naive implementation, hopefully optimized by the compiler
+		template<typename T>
+		void SinCos(T x, T* sin, T* cos)
+		{
+			*sin = std::sin(x);
+			*cos = std::cos(x);
+		}
 	}
 	/*!
 	* \ingroup math
@@ -108,6 +126,59 @@ namespace Nz
 	{
 	}
 
+	/*!
+	* \brief Computes the cosine of the angle
+	* \return Cosine of angle
+	*
+	* \see GetSinCos
+	*/
+	template<AngleUnit Unit, typename T>
+	T Angle<Unit, T>::GetCos() const
+	{
+		return std::cos(ToRadians().angle);
+	}
+
+	/*!
+	* \brief Computes the sine of the angle
+	* \return Sine of angle
+	*
+	* \see GetSinCos
+	*/
+	template<AngleUnit Unit, typename T>
+	T Angle<Unit, T>::GetSin() const
+	{
+		return std::sin(ToRadians().angle);
+	}
+
+	/*!
+	* \brief Computes both sines and cosines of the angle
+	* \return Sine and cosine of the angle
+	*
+	* \remark This is potentially faster than calling both GetSin and GetCos separately as it can computes both values at the same time.
+	*
+	* \see GetCos, GetSin
+	*/
+	template<AngleUnit Unit, typename T>
+	std::pair<T, T> Angle<Unit, T>::GetSinCos() const
+	{
+		T sin, cos;
+		Detail::SinCos<T>(ToRadians().angle, &sin, &cos);
+
+		return std::make_pair(sin, cos);
+	}
+
+	/*!
+	* \brief Computes the tangent of the angle
+	* \return Tangent value of the angle
+	*
+	* \see GetCos, GetSin
+	*/
+	template<AngleUnit Unit, typename T>
+	T Angle<Unit, T>::GetTan() const
+	{
+		return std::tan(ToRadians().angle);
+	}
+
 	/*!
 	* \brief Changes the angle value to zero
 	*/
@@ -115,6 +186,7 @@ namespace Nz
 	Angle<Unit, T>& Angle<Unit, T>::MakeZero()
 	{
 		angle = T(0);
+		return *this;
 	}
 
 	/*!
@@ -303,7 +375,7 @@ namespace Nz
 	template<AngleUnit Unit, typename T>
 	bool Angle<Unit, T>::operator==(const Angle& Angle) const
 	{
-		return NumberEquals(angle, Angle.angle);
+		return NumberEquals(angle, Angle.angle, Detail::AngleUtils<Unit>::GetEpsilon<T>());
 	}
 
 	/*!
@@ -315,7 +387,7 @@ namespace Nz
 	template<AngleUnit Unit, typename T>
 	bool Angle<Unit, T>::operator!=(const Angle& Angle) const
 	{
-		return !NumberEquals(angle, Angle.angle);
+		return !NumberEquals(angle, Angle.angle, Detail::AngleUtils<Unit>::GetEpsilon<T>());
 	}
 
 	/*!
diff --git a/tests/Engine/Math/Angle.cpp b/tests/Engine/Math/Angle.cpp
index 81e83c261..a4abc4a82 100644
--- a/tests/Engine/Math/Angle.cpp
+++ b/tests/Engine/Math/Angle.cpp
@@ -29,6 +29,26 @@ SCENARIO("Angle", "[MATH][ANGLE]")
 				CHECK(angle.ToRadians() == expectedResult);
 			}
 		}
+
+		WHEN("We compute its sinus/cosinus separatly")
+		{
+			THEN("It should be equal to 1 and 0")
+			{
+				CHECK(angle.GetSin() == Approx(1.f).margin(0.0001f));
+				CHECK(angle.GetCos() == Approx(0.f).margin(0.0001f));
+			}
+
+		}
+		AND_WHEN("We compute it at the same time")
+		{
+			auto sincos = angle.GetSinCos();
+
+			THEN("It should also be equal to 1 and 0")
+			{
+				CHECK(sincos.first == Approx(1.f).margin(0.0001f));
+				CHECK(sincos.second == Approx(0.f).margin(0.0001f));
+			}
+		}
 	}
 
 	GIVEN("A degree angle of 480deg")
@@ -48,9 +68,9 @@ SCENARIO("Angle", "[MATH][ANGLE]")
 		}
 	}
 
-	GIVEN("A degree angle of -270deg")
+	GIVEN("A degree angle of -300deg")
 	{
-		Nz::DegreeAnglef angle(-270.f);
+		Nz::DegreeAnglef angle(-300.f);
 
 		WHEN("We normalize it")
 		{
@@ -58,7 +78,7 @@ SCENARIO("Angle", "[MATH][ANGLE]")
 
 			THEN("It should be equal to a normalized version of itself")
 			{
-				Nz::DegreeAnglef expectedResult(90.f);
+				Nz::DegreeAnglef expectedResult(60.f);
 
 				CHECK(angle == expectedResult);
 			}
@@ -91,7 +111,28 @@ SCENARIO("Angle", "[MATH][ANGLE]")
 				CHECK(angle.ToDegrees() == expectedResult);
 			}
 		}
+
+		WHEN("We compute its sinus/cosinus separatly")
+		{
+			THEN("It should be equal to 0 and -1")
+			{
+				CHECK(angle.GetSin() == Approx(0.f).margin(0.0001f));
+				CHECK(angle.GetCos() == Approx(-1.f).margin(0.0001f));
+			}
+
+		}
+		AND_WHEN("We compute it at the same time")
+		{
+			auto sincos = angle.GetSinCos();
+
+			THEN("It should also be equal to 0 and -1")
+			{
+				CHECK(sincos.first == Approx(0.f).margin(0.0001f));
+				CHECK(sincos.second == Approx(-1.f).margin(0.0001f));
+			}
+		}
 	}
+
 	GIVEN("A radian angle of 7pi")
 	{
 		Nz::RadianAnglef angle(float(7 * M_PI));