Further Transform2D

include/J3ML/LinearAlgebra/Transform2D.hpp

@@ -4,61 +4,52 @@
 #include <J3ML/LinearAlgebra/Matrix3x3.hpp>
 
 namespace J3ML::LinearAlgebra {
+
+    /// A class that performs and represents translations, rotations, and scaling operations in two dimensions.
     class Transform2D {
     protected:
+        // TODO: Verify column-major order (or transpose it) for compatibility with OpenGL.
         Matrix3x3 transformation;
     public:
         const static Transform2D Identity;
         const static Transform2D FlipX;
         const static Transform2D FlipY;
 
-        /// Default constructor initializes to an Identity tansformation.
-        Transform2D()
-        {
-            transformation.Row(0) = {1, 0, 0};
-            transformation.Row(1) = {0, 1, 0};
-            transformation.Row(2) = {0, 0, 1};
-        }
+        /// Default constructor initializes to an Identity transformation.
+        Transform2D();
 
-        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);
-        }
-
-        static Transform2D FromScale(float sx, float sy)
-        {
-            Transform2D s;
-            s.transformation[0][0] = sx;
-            s.transformation[1][1] = sy;
-            return s;
-        }
-        static Transform2D FromScale(const Vector2& scale)
-        {
-            return FromScale(scale.x, scale.y);
-        }
         Transform2D(const Vector2& pos, const Vector2& scale, const Vector2& origin, const Vector2& skew, float rotation);
-        Transform2D(const Matrix3x3& transform);
+        explicit Transform2D(const Matrix3x3& transform);
+
+        static Transform2D FromScale(float sx, float sy);
+        static Transform2D FromScale(const Vector2& scale);
+        static Transform2D FromRotation(float radians);
+        static Transform2D FromTranslation(const Vector2& translation);
+        static Transform2D FromTranslation(float tx, float ty);
+
+        /// Returns a Transform2D
         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(const Vector2& scales); // Perform Nonuniform Scale
-        Transform2D Rotate();
-        Vector2 Transform(const Vector2& point) const
-        {
-            Vector2 result;
-            result.x = transformation.At(0,0) * point.x + transformation.At(0,1) * point.y + transformation.At(0,2);
-            result.y = transformation.At(1,0) * point.x + transformation.At(1,1) * point.y + transformation.At(1,2);
-            return result;
-        }
+        Transform2D Scale(float scale);
+        Transform2D Scale(float x, float y);
+        Transform2D Scale(const Vector2& scales);
+        Transform2D Rotate(float radians);
+
+        /// Transforms a given 2D point by this transformation.
+        Vector2 Transform(const Vector2& point) const;
         Transform2D Inverse() const;
         Transform2D AffineInverse() const;
+
+        Vector2 ForwardVector() const;
+        Vector2 UpVector() const;
+
         float Determinant() const;
-        Vector2 GetOrigin() const;
+        float& At(int row, int col);
+        [[nodiscard]] float At(int row, int col) const;
+
+        Vector2 GetTranslation() const;
         float GetRotation() const;
         Vector2 GetScale() const;
-        float GetSkew() const;
         Transform2D OrthoNormalize();
     };
 }

src/J3ML/LinearAlgebra/Transform2D.cpp

@@ -27,4 +27,71 @@ namespace J3ML::LinearAlgebra {
     Transform2D Transform2D::Translate(const LinearAlgebra::Vector2 &input) const {
         return Translate(input.x, input.y);
     }
+
+    Transform2D::Transform2D() {
+        transformation = Matrix3x3::Identity;
+    }
+
+    Transform2D Transform2D::FromRotation(float radians) {
+        float c = Math::Cos(radians);
+        float s = Math::Sin(radians);
+        return Transform2D(Matrix3x3(
+                c, s, 0.f,
+                -s, c, 0.f,
+                0.f, 0.f, 1.f));
+    }
+
+    Transform2D Transform2D::FromScale(const Vector2 &scale) {
+        return FromScale(scale.x, scale.y);
+    }
+
+    Transform2D Transform2D::FromScale(float sx, float sy) {
+        Transform2D s;
+        s.transformation[0][0] = sx;
+        s.transformation[1][1] = sy;
+        return s;
+    }
+
+    Transform2D Transform2D::FromTranslation(const Vector2 &translation) {
+        return FromTranslation(translation.x, translation.y);
+    }
+
+    Transform2D Transform2D::FromTranslation(float tx, float ty) {
+        return Transform2D(Matrix3x3(
+                1.f, 0.f, 0.f,
+                0.f, 1.f, 0.f,
+                tx,  ty,  1.f));
+    }
+
+    Vector2 Transform2D::GetScale() const {
+        return {
+                Math::Sqrt(At(0,0) * At(0,0) + At(0,1) * At(0,1)),
+                Math::Sqrt(At(1,0) * At(1,0) + At(1,1) * At(1,1))
+        };
+    }
+
+    float Transform2D::GetRotation() const {
+        return Math::Atan2(At(1, 0), At(0, 0));
+    }
+
+    Vector2 Transform2D::GetTranslation() const {
+        return {At(2,0), At(2, 1)};
+    }
+
+    float &Transform2D::At(int row, int col) { return transformation.At(row, col); }
+
+    float Transform2D::At(int row, int col) const { return transformation.At(row, col); }
+
+    float Transform2D::Determinant() const { return transformation.Determinant(); }
+
+    Vector2 Transform2D::Transform(const Vector2 &point) const {
+        Vector2 result;
+        result.x = At(0,0) * point.x + At(0,1) * point.y + At(0,2);
+        result.y = At(1,0) * point.x + At(1,1) * point.y + At(1,2);
+        return result;
+    }
+
+    Vector2 Transform2D::ForwardVector() const { return {At(0,0), At(1,0)}; }
+
+    Vector2 Transform2D::UpVector() const { return {At(0,1), At(1,1)}; }
 }