From d012af1214295b3c57bba336b66f007a7ff45229 Mon Sep 17 00:00:00 2001
From: josh <josh@stepbro.wtf>
Date: Tue, 23 Jan 2024 21:46:07 -0500
Subject: [PATCH] Implement Transform2D

---
 include/J3ML/LinearAlgebra/Matrix3x3.h   | 13 +++++++---
 include/J3ML/LinearAlgebra/Transform2D.h | 30 ++++++++++++++++++------
 src/J3ML/LinearAlgebra/Matrix3x3.cpp     |  5 ++++
 src/J3ML/LinearAlgebra/Transform2D.cpp   | 25 ++++++++++++++++++++
 4 files changed, 63 insertions(+), 10 deletions(-)

diff --git a/include/J3ML/LinearAlgebra/Matrix3x3.h b/include/J3ML/LinearAlgebra/Matrix3x3.h
index 51aff49..58e3e8b 100644
--- a/include/J3ML/LinearAlgebra/Matrix3x3.h
+++ b/include/J3ML/LinearAlgebra/Matrix3x3.h
@@ -58,6 +58,7 @@ namespace LinearAlgebra {
 
         void SetRow(int i, const Vector3 &vector3);
         void SetColumn(int i, const Vector3& vector);
+        void SetAt(int x, int y, float value);
 
         void Orthonormalize(int c0, int c1, int c2)
         {
@@ -85,14 +86,20 @@ namespace LinearAlgebra {
         // Transforming a vector v using this matrix computes the vector
         // v' == M * v == R*S*v == (R * (S * v)) which means the scale operation
         // is applied to the vector first, followed by rotation, and finally translation
-        static Matrix3x3 FromRS(const Quaternion& rotate, const Matrix3x3& scale);
-        static Matrix3x3 FromRS(const Matrix3x3 &rotate, const Matrix3x3& scale);
+        static Matrix3x3 FromRS(const Quaternion& rotate, const Vector3& scale)
+        {
+            return Matrix3x3(rotate) * Matrix3x3::Scale(scale);
+        }
+        static Matrix3x3 FromRS(const Matrix3x3 &rotate, const Vector3& scale)
+        {
+            return rotate * Matrix3x3::Scale(scale);
+        }
 
 
         /// Creates a new transformation matrix that scales by the given factors.
         // This matrix scales with respect to origin.
         static Matrix3x3 Scale(float sx, float sy, float sz);
-        static Matrix3x3 Scale(const Matrix3x3& scale);
+        static Matrix3x3 Scale(const Vector3& scale);
 
         /// Returns the main diagonal.
         Vector3 Diagonal() const;
diff --git a/include/J3ML/LinearAlgebra/Transform2D.h b/include/J3ML/LinearAlgebra/Transform2D.h
index bd1078e..345ce4a 100644
--- a/include/J3ML/LinearAlgebra/Transform2D.h
+++ b/include/J3ML/LinearAlgebra/Transform2D.h
@@ -8,17 +8,33 @@ namespace LinearAlgebra {
     protected:
         Matrix3x3 transformation;
     public:
+
+        const static Transform2D Identity;
+        const static Transform2D FlipX;
+        const static Transform2D FlipY;
+
+        Transform2D(float rotation, const Vector2& pos);
+        Transform2D(float px, float py, float sx, float sy, float ox, float oy, float kx, float ky, float rotation)
+        {
+            transformation = Matrix3x3(px, py, rotation, sx, sy, ox, oy, kx, ky);
+        }
+        Transform2D(const Vector2& pos, const Vector2& scale, const Vector2& origin, const Vector2& skew, float rotation);
+        Transform2D(const Matrix3x3& transform);
         Transform2D Translate(const Vector2& offset) const;
         Transform2D Translate(float x, float y) const;
-        Transform2D Scale(float scale); // Perform Uniform Scale
-        Transform2D Scale(float x, float y); // Perform Nonunform Scale
+        Transform2D Scale(float scale);           // Perform Uniform Scale
+        Transform2D Scale(float x, float y);      // Perform Nonunform Scale
         Transform2D Scale(const Vector2& scales); // Perform Nonuniform Scale
         Transform2D Rotate();
-
-        Vector2 Transform(const Vector2& input) const
-        {
-            return transformation * input;
-        }
+        Vector2 Transform(const Vector2& input) const;
+        Transform2D Inverse() const;
+        Transform2D AffineInverse() const;
+        float Determinant() const;
+        Vector2 GetOrigin() const;
+        float GetRotation() const;
+        Vector2 GetScale() const;
+        float GetSkew() const;
+        Transform2D OrthoNormalize();
     };
 }
 
diff --git a/src/J3ML/LinearAlgebra/Matrix3x3.cpp b/src/J3ML/LinearAlgebra/Matrix3x3.cpp
index b246c2c..0d2273b 100644
--- a/src/J3ML/LinearAlgebra/Matrix3x3.cpp
+++ b/src/J3ML/LinearAlgebra/Matrix3x3.cpp
@@ -37,9 +37,14 @@ namespace LinearAlgebra {
         return {x, y, z};
     }
 
+
     float Matrix3x3::At(int x, int y) const {
         return this->elems[x][y];
+    }
 
+    void Matrix3x3::SetAt(int x, int y, float value)
+    {
+        this->elems[x][y] = value;
     }
 
     Vector3 Matrix3x3::operator*(const Vector3 &rhs) const {
diff --git a/src/J3ML/LinearAlgebra/Transform2D.cpp b/src/J3ML/LinearAlgebra/Transform2D.cpp
index 4f335ae..8705120 100644
--- a/src/J3ML/LinearAlgebra/Transform2D.cpp
+++ b/src/J3ML/LinearAlgebra/Transform2D.cpp
@@ -2,4 +2,29 @@
 
 namespace LinearAlgebra {
 
+    const Transform2D Transform2D::Identity = Transform2D({0, 0}, {1, 1}, {0,0}, {0,0}, 0);
+    const Transform2D Transform2D::FlipX    = Transform2D({0, 0}, {-1, 1}, {0,0}, {0,0}, 0);
+    const Transform2D Transform2D::FlipY    = Transform2D({0, 0}, {1, -1}, {0,0}, {0,0}, 0);
+
+
+    Vector2 Transform2D::Transform(const Vector2 &input) const {
+        return transformation * input;
+    }
+
+    Transform2D::Transform2D(const Matrix3x3 &transform) : transformation(transform) { }
+
+    Transform2D::Transform2D(const Vector2& pos, const Vector2& scale, const Vector2& origin, const Vector2& skew, float rotation) {
+        transformation = Matrix3x3(pos.x, pos.y, rotation, scale.x, scale.y, origin.x, origin.y, skew.x, skew.y);
+    }
+
+    Transform2D Transform2D::Translate(float x, float y) const {
+        auto copy = Matrix3x3(transformation);
+        copy.SetAt(0, 0, transformation.At(0, 0) + x);
+        copy.SetAt(0, 1, transformation.At(0, 1) + y);
+        return Transform2D(copy);
+    }
+
+    Transform2D Transform2D::Translate(const LinearAlgebra::Vector2 &input) const {
+        return Translate(input.x, input.y);
+    }
 }
\ No newline at end of file