--- /dev/null
+/*
+This file is part of GtkRadiant.
+
+GtkRadiant 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.
+
+GtkRadiant 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 GtkRadiant; if not, write to the Free Software
+Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+*/
+
+#if !defined(INCLUDED_FILTERS_H)
+#define INCLUDED_FILTERS_H
+
+void filter_level(int flag);
+void filter_stepon(void);
+void filter_actorclip(void);
+void filter_weaponclip(void);
+void filter_nodraw(void);
+
+#define SURF_NODRAW 0x80
+
+#define CONTENTS_LEVEL8 0x8000
+#define CONTENTS_LEVEL7 0x4000
+#define CONTENTS_LEVEL6 0x2000
+#define CONTENTS_LEVEL5 0x1000
+#define CONTENTS_LEVEL4 0x0800
+#define CONTENTS_LEVEL3 0x0400
+#define CONTENTS_LEVEL2 0x0200
+#define CONTENTS_LEVEL1 0x0100
+#define CONTENTS_ACTORCLIP 0x10000
+#define CONTENTS_WEAPONCLIP 0x2000000
+#define CONTENTS_STEPON 0x40000000
+
+#endif