Merge pull request #25831 from aaronfranke/mono-trans-rot-scale

[Core] [Mono] Transform2D rotation and scale fixes

4 files changed, 63 insertions, 16 deletions

diff --git a/core/math/basis.cpp b/core/math/basis.cpp
index 8e4eacd9a6..7f60b7962c 100644
--- a/core/math/basis.cpp
+++ b/core/math/basis.cpp
@@ -258,7 +258,7 @@ Vector3 Basis::get_scale_abs() const {
 }
 
 Vector3 Basis::get_scale_local() const {
-	real_t det_sign = determinant() > 0 ? 1 : -1;
+	real_t det_sign = SGN(determinant());
 	return det_sign * Vector3(elements[0].length(), elements[1].length(), elements[2].length());
 }
 
@@ -284,7 +284,7 @@ Vector3 Basis::get_scale() const {
 	// matrix elements.
 	//
 	// The rotation part of this decomposition is returned by get_rotation* functions.
-	real_t det_sign = determinant() > 0 ? 1 : -1;
+	real_t det_sign = SGN(determinant());
 	return det_sign * Vector3(
 							  Vector3(elements[0][0], elements[1][0], elements[2][0]).length(),
 							  Vector3(elements[0][1], elements[1][1], elements[2][1]).length(),
diff --git a/core/math/transform_2d.cpp b/core/math/transform_2d.cpp
index 295e60babb..7d00158f3d 100644
--- a/core/math/transform_2d.cpp
+++ b/core/math/transform_2d.cpp
@@ -80,13 +80,14 @@ real_t Transform2D::get_rotation() const {
 }
 
 void Transform2D::set_rotation(real_t p_rot) {
-
+	Size2 scale = get_scale();
 	real_t cr = Math::cos(p_rot);
 	real_t sr = Math::sin(p_rot);
 	elements[0][0] = cr;
 	elements[0][1] = sr;
 	elements[1][0] = -sr;
 	elements[1][1] = cr;
+	set_scale(scale);
 }
 
 Transform2D::Transform2D(real_t p_rot, const Vector2 &p_pos) {
@@ -101,10 +102,17 @@ Transform2D::Transform2D(real_t p_rot, const Vector2 &p_pos) {
 }
 
 Size2 Transform2D::get_scale() const {
-	real_t det_sign = basis_determinant() > 0 ? 1 : -1;
+	real_t det_sign = SGN(basis_determinant());
 	return Size2(elements[0].length(), det_sign * elements[1].length());
 }
 
+void Transform2D::set_scale(Size2 &p_scale) {
+	elements[0].normalize();
+	elements[1].normalize();
+	elements[0] *= p_scale.x;
+	elements[1] *= p_scale.y;
+}
+
 void Transform2D::scale(const Size2 &p_scale) {
 	scale_basis(p_scale);
 	elements[2] *= p_scale;
diff --git a/core/math/transform_2d.h b/core/math/transform_2d.h
index 507e6a16eb..b9e7a36fb3 100644
--- a/core/math/transform_2d.h
+++ b/core/math/transform_2d.h
@@ -81,6 +81,7 @@ struct Transform2D {
 	real_t basis_determinant() const;
 
 	Size2 get_scale() const;
+	void set_scale(Size2 &p_scale);
 
 	_FORCE_INLINE_ const Vector2 &get_origin() const { return elements[2]; }
 	_FORCE_INLINE_ void set_origin(const Vector2 &p_origin) { elements[2] = p_origin; }
diff --git a/modules/mono/glue/Managed/Files/Transform2D.cs b/modules/mono/glue/Managed/Files/Transform2D.cs
index f89c99cff2..df7ba3402d 100644
--- a/modules/mono/glue/Managed/Files/Transform2D.cs
+++ b/modules/mono/glue/Managed/Files/Transform2D.cs
@@ -17,12 +17,40 @@ namespace Godot
 
         public real_t Rotation
         {
-            get { return Mathf.Atan2(y.x, origin.y); }
+            get
+            {
+                real_t det = BasisDeterminant();
+                Transform2D t = Orthonormalized();
+                if (det < 0)
+                {
+                    t.ScaleBasis(new Vector2(1, -1));
+                }
+                return Mathf.Atan2(t.x.y, t.x.x);
+            }
+            set
+            {
+                Vector2 scale = Scale;
+                x.x = y.y = Mathf.Cos(value);
+                x.y = y.x = Mathf.Sin(value);
+                y.x *= -1;
+                Scale = scale;
+            }
         }
 
         public Vector2 Scale
         {
-            get { return new Vector2(x.Length(), y.Length()); }
+            get
+            {
+                real_t detSign = Mathf.Sign(BasisDeterminant());
+                return new Vector2(x.Length(), detSign * y.Length());
+            }
+            set
+            {
+                x = x.Normalized();
+                y = y.Normalized();
+                x *= value.x;
+                y *= value.y;
+            }
         }
 
         public Vector2 this[int index]
@@ -95,7 +123,7 @@ namespace Godot
         {
             var inv = this;
 
-            real_t det = this[0, 0] * this[1, 1] - this[1, 0] * this[0, 1];
+            real_t det = BasisDeterminant();
 
             if (det == 0)
             {
@@ -107,20 +135,25 @@ namespace Godot
                 );
             }
 
-            real_t idet = 1.0f / det;
+            real_t detInv = 1.0f / det;
 
             real_t temp = this[0, 0];
             this[0, 0] = this[1, 1];
             this[1, 1] = temp;
 
-            this[0] *= new Vector2(idet, -idet);
-            this[1] *= new Vector2(-idet, idet);
+            this[0] *= new Vector2(detInv, -detInv);
+            this[1] *= new Vector2(-detInv, detInv);
 
             this[2] = BasisXform(-this[2]);
 
             return inv;
         }
 
+        private real_t BasisDeterminant()
+        {
+            return x.x * y.y - x.y * y.x;
+        }
+
         public Vector2 BasisXform(Vector2 v)
         {
             return new Vector2(Tdotx(v), Tdoty(v));
@@ -220,6 +253,14 @@ namespace Godot
             return copy;
         }
 
+        private void ScaleBasis(Vector2 scale)
+        {
+            x.x *= scale.x;
+            x.y *= scale.y;
+            y.x *= scale.x;
+            y.y *= scale.y;
+        }
+
         private real_t Tdotx(Vector2 with)
         {
             return this[0, 0] * with[0] + this[1, 0] * with[1];
@@ -274,12 +315,9 @@ namespace Godot
 
         public Transform2D(real_t rot, Vector2 pos)
         {
-            real_t cr = Mathf.Cos(rot);
-            real_t sr = Mathf.Sin(rot);
-            x.x = cr;
-            x.y = -sr;
-            y.x = sr;
-            y.y = cr;
+            x.x = y.y = Mathf.Cos(rot);
+            x.y = y.x = Mathf.Sin(rot);
+            y.x *= -1;
             origin = pos;
         }