- detached the poly renderer from the software renderer

src/polyrenderer/scene/poly_light.cpp

@@ -0,0 +1,43 @@
+/*
+**  Light calculations
+**  Copyright (c) 2016 Magnus Norddahl
+**
+**  This software is provided 'as-is', without any express or implied
+**  warranty.  In no event will the authors be held liable for any damages
+**  arising from the use of this software.
+**
+**  Permission is granted to anyone to use this software for any purpose,
+**  including commercial applications, and to alter it and redistribute it
+**  freely, subject to the following restrictions:
+**
+**  1. The origin of this software must not be misrepresented; you must not
+**     claim that you wrote the original software. If you use this software
+**     in a product, an acknowledgment in the product documentation would be
+**     appreciated but is not required.
+**  2. Altered source versions must be plainly marked as such, and must not be
+**     misrepresented as being the original software.
+**  3. This notice may not be removed or altered from any source distribution.
+**
+*/
+
+#include <stdlib.h>
+#include "templates.h"
+#include "doomdef.h"
+#include "sbar.h"
+#include "poly_light.h"
+
+fixed_t PolyLightVisibility::LightLevelToShade(int lightlevel, bool foggy)
+{
+	bool nolightfade = !foggy && ((level.flags3 & LEVEL3_NOLIGHTFADE));
+	if (nolightfade)
+	{
+		return (MAX(255 - lightlevel, 0) * NUMCOLORMAPS) << (FRACBITS - 8);
+	}
+	else
+	{
+		// Convert a light level into an unbounded colormap index (shade). Result is
+		// fixed point. Why the +12? I wish I knew, but experimentation indicates it
+		// is necessary in order to best reproduce Doom's original lighting.
+		return (NUMCOLORMAPS * 2 * FRACUNIT) - ((lightlevel + 12) * (FRACUNIT*NUMCOLORMAPS / 128));
+	}
+}