From 741dc6b7e8e60b7747e8dca9b4e58bed868af499 Mon Sep 17 00:00:00 2001
From: SirLynix <lynix680@gmail.com>
Date: Tue, 16 May 2023 15:43:05 +0200
Subject: [PATCH] Math/Box: Add ScaleAroundCenter

---
 include/Nazara/Math/Box.hpp             |  3 ++
 include/Nazara/Math/Box.inl             | 40 +++++++++++++++++++++++++
 tests/UnitTests/Engine/Math/BoxTest.cpp | 37 +++++++++++++++++++++++
 3 files changed, 80 insertions(+)

diff --git a/include/Nazara/Math/Box.hpp b/include/Nazara/Math/Box.hpp
index 19f4c9990..1f06d421d 100644
--- a/include/Nazara/Math/Box.hpp
+++ b/include/Nazara/Math/Box.hpp
@@ -64,6 +64,9 @@ namespace Nz
 			Box& Scale(T scalar);
 			Box& Scale(const Vector3<T>& vec);
 
+			Box& ScaleAroundCenter(T scalar);
+			Box& ScaleAroundCenter(const Vector3<T>& vec);
+
 			std::string ToString() const;
 
 			Box& Transform(const Matrix4<T>& matrix, bool applyTranslation = true);
diff --git a/include/Nazara/Math/Box.inl b/include/Nazara/Math/Box.inl
index 8e89d8b6c..15f1e6811 100644
--- a/include/Nazara/Math/Box.inl
+++ b/include/Nazara/Math/Box.inl
@@ -545,6 +545,46 @@ namespace Nz
 
 		return *this;
 	}
+	
+	/*!
+	* \brief Multiplies the lengths of this box with the scalar (the box center doesn't move)
+	* \return A reference to this box where lengths are the product of these lengths and the scalar
+	*
+	* \param scalar The scalar to multiply width, height and depth with
+	*/
+	template<typename T>
+	Box<T>& Box<T>::ScaleAroundCenter(T scalar)
+	{
+		x -= (width  * scalar - width)  / T(2.0);
+		y -= (height * scalar - height) / T(2.0);
+		z -= (depth  * scalar - depth)  / T(2.0);
+
+		width  *= scalar;
+		height *= scalar;
+		depth  *= scalar;
+
+		return *this;
+	}
+
+	/*!
+	* \brief Multiplies the lengths of this box with the vector but changes the origin (the box center doesn't move)
+	* \return A reference to this box where width, height and depth are the product of the old width,  height and depth with the vec
+	*
+	* \param vec The vector where component one multiply width, two height and three depth
+	*/
+	template<typename T>
+	Box<T>& Box<T>::ScaleAroundCenter(const Vector3<T>& vec)
+	{
+		x -= (width  * vec.x - width)  / T(2.0);
+		y -= (height * vec.y - height) / T(2.0);
+		z -= (depth  * vec.z - depth)  / T(2.0);
+
+		width  *= vec.x;
+		height *= vec.y;
+		depth  *= vec.z;
+
+		return *this;
+	}
 
 	/*!
 	* \brief Gives a string representation
diff --git a/tests/UnitTests/Engine/Math/BoxTest.cpp b/tests/UnitTests/Engine/Math/BoxTest.cpp
index c11b6ea7b..ede8a6cdf 100644
--- a/tests/UnitTests/Engine/Math/BoxTest.cpp
+++ b/tests/UnitTests/Engine/Math/BoxTest.cpp
@@ -89,6 +89,43 @@ SCENARIO("Box", "[MATH][BOX]")
 				REQUIRE(Nz::Boxf::Lerp(nullBox, centerAndUnit, 0.5f) == result);
 			}
 		}
+
+		WHEN("We scale the boxes")
+		{
+			WHEN("We scale uniformly")
+			{
+				firstCenterAndUnit.Scale(2.f);
+				CHECK(firstCenterAndUnit.GetCenter() == Nz::Vector3f::Unit());
+				CHECK(firstCenterAndUnit.GetLengths() == 2.f * Nz::Vector3f::Unit());
+			}
+
+			WHEN("We scale non-uniformly")
+			{
+				firstCenterAndUnit.Scale({ 2.f, 1.f, 0.01f });
+				CHECK(firstCenterAndUnit.GetCenter() == Nz::Vector3f(1.f, 0.5f, 0.005f));
+				CHECK(firstCenterAndUnit.GetLengths() == Nz::Vector3f(2.f, 1.f, 0.01f));
+			}
+
+			WHEN("We scale uniformly around center")
+			{
+				Nz::Vector3f center = firstCenterAndUnit.GetCenter();
+
+				firstCenterAndUnit.ScaleAroundCenter(2.f);
+
+				CHECK(firstCenterAndUnit.GetCenter() == center);
+				CHECK(firstCenterAndUnit.GetLengths() == 2.f * Nz::Vector3f::Unit());
+			}
+
+			WHEN("We scale non-uniformly around center")
+			{
+				Nz::Vector3f center = firstCenterAndUnit.GetCenter();
+
+				firstCenterAndUnit.ScaleAroundCenter({ 2.f, 1.f, 0.01f });
+
+				CHECK(firstCenterAndUnit.GetCenter() == center);
+				CHECK(firstCenterAndUnit.GetLengths() == Nz::Vector3f(2.f, 1.f, 0.01f));
+			}
+		}
 	}
 
 	GIVEN("Two wrong box (negative width, height and depth")