diff --git a/source/graphics/ModelAbstract.h b/source/graphics/ModelAbstract.h
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+/* Copyright (C) 2011 Wildfire Games.
+ * This file is part of 0 A.D.
+ *
+ * 0 A.D. is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 0 A.D. is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef INCLUDED_MODELABSTRACT
+#define INCLUDED_MODELABSTRACT
+
+#include "graphics/RenderableObject.h"
+#include "ps/Overlay.h"
+
+class CModel;
+class CModelDecal;
+
+/**
+ * Abstract base class for graphical objects that are used by units,
+ * or as props attached to other CModelAbstract objects.
+ * This includes meshes, terrain decals, and sprites.
+ * These objects exist in a tree hierarchy.
+ */
+class CModelAbstract : public CRenderableObject
+{
+	NONCOPYABLE(CModelAbstract);
+
+public:
+	CModelAbstract() :
+		m_Parent(NULL), m_PositionValid(false),
+		m_ShadingColor(1, 1, 1, 1), m_PlayerID((size_t)-1)
+	{
+	}
+
+	virtual CModelAbstract* Clone() const = 0;
+
+	/// Dynamic cast
+	virtual CModel* ToCModel() { return NULL; }
+
+	/// Dynamic cast
+	virtual CModelDecal* ToCModelDecal() { return NULL; }
+
+	// (This dynamic casting is a bit ugly, but we won't have many subclasses
+	// and this seems the easiest way to integrate with other code that wants
+	// type-specific processing)
+
+	/**
+	 * Calls SetDirty on this model and all child objects.
+	 */
+	virtual void SetDirtyRec(int dirtyflags) = 0;
+
+	/**
+	 * Called when terrain has changed in the given inclusive bounds.
+	 * Might call SetDirty if the change affects this model.
+	 */
+	virtual void SetTerrainDirty(ssize_t i0, ssize_t j0, ssize_t i1, ssize_t j1) = 0;
+
+	/**
+	 * Ensure that both the transformation and the bone
+	 * matrices are correct for this model and all its props.
+	 */
+	virtual void ValidatePosition() = 0;
+
+	/**
+	 * Mark this model's position and bone matrices,
+	 * and all props' positions as invalid.
+	 */
+	virtual void InvalidatePosition() = 0;
+
+	virtual void SetPlayerID(size_t id) { m_PlayerID = id; }
+
+	// get the model's player ID; initial default is (size_t)-1
+	virtual size_t GetPlayerID() const { return m_PlayerID; }
+
+	virtual void SetShadingColor(const CColor& colour) { m_ShadingColor = colour; }
+	virtual CColor GetShadingColor() const { return m_ShadingColor; }
+
+	/// If non-null points to the model that we are attached to.
+	CModelAbstract* m_Parent;
+
+	/// True if both transform and and bone matrices are valid.
+	bool m_PositionValid;
+
+	size_t m_PlayerID;
+
+	// modulating color
+	CColor m_ShadingColor;
+};
+
+#endif // INCLUDED_MODELABSTRACT