From aec8ef98dd6379af03ee7bdf46a80f504ae0e289 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Vladim=C3=ADr=20Vondru=C5=A1?= <mosra@centrum.cz>
Date: Mon, 23 Apr 2012 00:09:41 +0200
Subject: [PATCH] Function for returning rotation and scaling part of Matrix4.

---
 src/Math/Matrix4.h            |  8 ++++++++
 src/Math/Test/Matrix4Test.cpp | 17 +++++++++++++++++
 src/Math/Test/Matrix4Test.h   |  1 +
 3 files changed, 26 insertions(+)

diff --git a/src/Math/Matrix4.h b/src/Math/Matrix4.h
index 08cde955b..a5d8eb4ed 100644
--- a/src/Math/Matrix4.h
+++ b/src/Math/Matrix4.h
@@ -169,6 +169,14 @@ template<class T> class Matrix4: public Matrix<T, 4> {
         /** @copydoc Matrix::inverted() */
         inline Matrix4<T> inverted() const { return Matrix<T, 4>::inverted(); }
 
+        /** @brief Rotation and scaling part of the matrix */
+        inline Matrix3<T> rotationScaling() const {
+            return Matrix3<T>::from(
+                (*this)[0].xyz(),
+                (*this)[1].xyz(),
+                (*this)[2].xyz());
+        }
+
         /** @brief Rotation part of the matrix */
         inline Matrix3<T> rotation() const {
             return Matrix3<T>::from(
diff --git a/src/Math/Test/Matrix4Test.cpp b/src/Math/Test/Matrix4Test.cpp
index ecbac538f..a93036b31 100644
--- a/src/Math/Test/Matrix4Test.cpp
+++ b/src/Math/Test/Matrix4Test.cpp
@@ -88,6 +88,23 @@ void Matrix4Test::rotation() {
     QVERIFY(Matrix4::rotation(deg(-74.0f), {-1.0f, 2.0f, 2.0f}) == matrix);
 }
 
+void Matrix4Test::rotationScalingPart() {
+    Matrix4 m(
+        3.0f, 5.0f, 8.0f, 4.0f,
+        4.0f, 4.0f, 7.0f, 3.0f,
+        7.0f, -1.0f, 8.0f, 0.0f,
+        9.0f, 4.0f, 5.0f, 9.0f
+    );
+
+    Matrix3 expected(
+        3.0f, 5.0f, 8.0f,
+        4.0f, 4.0f, 7.0f,
+        7.0f, -1.0f, 8.0f
+    );
+
+    QVERIFY(m.rotationScaling() == expected);
+}
+
 void Matrix4Test::rotationPart() {
     Matrix3 expectedRotationPart(
         0.35612214f,  -0.80181062f, 0.47987163f,
diff --git a/src/Math/Test/Matrix4Test.h b/src/Math/Test/Matrix4Test.h
index 857ace581..026533dba 100644
--- a/src/Math/Test/Matrix4Test.h
+++ b/src/Math/Test/Matrix4Test.h
@@ -28,6 +28,7 @@ class Matrix4Test: public QObject {
         void translation();
         void scaling();
         void rotation();
+        void rotationScalingPart();
         void rotationPart();
 
         void debug();