Readd CSceneCollisionManager with only the method we need

include/ISceneCollisionManager.h

@@ -0,0 +1,38 @@
+// Copyright (C) 2002-2012 Nikolaus Gebhardt
+// This file is part of the "Irrlicht Engine".
+// For conditions of distribution and use, see copyright notice in irrlicht.h
+
+#ifndef __I_SCENE_COLLISION_MANAGER_H_INCLUDED__
+#define __I_SCENE_COLLISION_MANAGER_H_INCLUDED__
+
+#include "IReferenceCounted.h"
+#include "position2d.h"
+#include "line3d.h"
+
+namespace irr
+{
+
+namespace scene
+{
+	class ICameraSceneNode;
+
+	class ISceneCollisionManager : public virtual IReferenceCounted
+	{
+	public:
+
+		//! Returns a 3d ray which would go through the 2d screen coordinates.
+		/** \param pos: Screen coordinates in pixels.
+		\param camera: Camera from which the ray starts. If null, the
+		active camera is used.
+		\return Ray starting from the position of the camera and ending
+		at a length of the far value of the camera at a position which
+		would be behind the 2d screen coordinates. */
+		virtual core::line3d<f32> getRayFromScreenCoordinates(
+			const core::position2d<s32>& pos, const ICameraSceneNode* camera = 0) = 0;
+
+	};
+
+} // end namespace scene
+} // end namespace irr
+
+#endif