SceneGraph: added AbstractObject::transformationMatrix().

Complement for Object::transformation(), usable from features which
don't want/need to upcast AbstractObject pointer.

src/SceneGraph/AbstractObject.h

@@ -102,6 +102,13 @@ template<std::uint8_t dimensions, class T = GLfloat> class AbstractObject
 
         /** @{ @name Object transformation */
 
+        /**
+         * @brief Transformation matrix
+         *
+         * @see Object::transformation()
+         */
+        virtual typename DimensionTraits<dimensions, T>::MatrixType transformationMatrix() const = 0;
+
         /**
          * @brief Transformation matrix relative to root object
          *

src/SceneGraph/Object.h

@@ -202,6 +202,10 @@ template<class Transformation> class Object: public AbstractObject<Transformatio
 
         /** @{ @name Object transformation */
 
+        inline typename DimensionTraits<Transformation::Dimensions, typename Transformation::Type>::MatrixType transformationMatrix() const override {
+            return Transformation::toMatrix(Transformation::transformation());
+        }
+
         inline typename DimensionTraits<Transformation::Dimensions, typename Transformation::Type>::MatrixType absoluteTransformationMatrix() const override {
             return Transformation::toMatrix(absoluteTransformation());
         }

src/SceneGraph/Test/ObjectTest.cpp

@@ -110,6 +110,8 @@ void ObjectTest::absoluteTransformation() {
     /* Proper transformation composition */
     Object3D o(&s);
     o.translate(Vector3::xAxis(2.0f));
+    CORRADE_COMPARE(o.transformation(), Matrix4::translation(Vector3::xAxis(2.0f)));
+    CORRADE_COMPARE(o.transformation(), o.transformationMatrix());
     Object3D o2(&o);
     o2.rotateY(deg(90.0f));
     CORRADE_COMPARE(o2.absoluteTransformation(),