Sync with upstream (Issue #30).

Recompiled tier1 and mathlib  for all platforms will come in next commit.

public/materialsystem/combineoperations.h

@@ -0,0 +1,29 @@
+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+// $NoKeywords: $
+//=============================================================================//
+
+#ifndef COMBINEOPERATIONS_H
+#define COMBINEOPERATIONS_H
+#pragma once
+
+// New combines can be written in the middle (and generally should be written before Error).
+// Keep these in sync with cCombineMaterialName in ctexturecompositor.cpp
+enum ECombineOperation
+{
+	ECO_Multiply = 0,
+	ECO_Add,
+	ECO_Lerp,
+
+	ECO_Select,
+
+	ECO_Legacy_Lerp_FirstPass,
+	ECO_Legacy_Lerp_SecondPass,
+
+	ECO_Error,
+	ECO_COUNT
+};
+
+#endif /* COMBINEOPERATIONS_H */