Add option to allow nodes to ignore the scale/rotation parts of their parents transformation.

ISceneNode::setUpdateAbsolutePosBehavior can now control what ISceneNode::updateAbsolutePosition really does.
Having only the position and not the rotation/scale of a child node affected by the parent transformation was previously impossible inside the scene-graph. So people always had to break the scene-graph and code it themselves.
Old behaviour is default. 
Extra check for new variable has a small cost, thought new behaviour can actually be faster when it's used.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@6432 dfc29bdd-3216-0410-991c-e03cc46cb475

include/ESceneNodeUpdateAbs.h

@@ -0,0 +1,34 @@
+// This file is part of the "Irrlicht Engine".
+// For conditions of distribution and use, see copyright notice in irrlicht.h
+
+#ifndef IRR_E_SCENE_NODE_UPDATE_ABS_H_INCLUDED
+#define IRR_E_SCENE_NODE_UPDATE_ABS_H_INCLUDED
+
+namespace irr
+{
+namespace scene
+{
+	//! Options how ISceneNode::updateAbsolutePosition calculates the AbsoluteTransformation
+	enum ESCENE_NODE_UPDATE_ABS
+	{
+		//! Node and parent transformation matrices are multiplied (default)
+		ESNUA_TRANSFORM_MATRIX,
+
+		//! Only transform the position of the node transformation matrix 
+		//! by the parent transformation matrix.
+		//! Parent will not affect the rotation/scale of the node transformation.
+		ESNUA_TRANSFORM_POSITION
+	};
+
+	//! Names for culling type
+	const c8* const SceneNodeUpdateAbsNames[] =
+	{
+		"matrix",
+		"pos",
+		0
+	};
+
+} // end namespace scene
+} // end namespace irr
+
+#endif