Make IsFullyDark/IsFullyLit respect hell and hellfire levels

Source/engine/render/dun_render.cpp

@@ -284,12 +284,12 @@ DVL_ALWAYS_INLINE Clip CalculateClip(int_fast16_t x, int_fast16_t y, int_fast16_
 
 DVL_ALWAYS_INLINE bool IsFullyDark(const uint8_t *DVL_RESTRICT tbl)
 {
-	return tbl == LightTables[LightsMax].data();
+	return tbl == FullyDarkLightTable;
 }
 
 DVL_ALWAYS_INLINE bool IsFullyLit(const uint8_t *DVL_RESTRICT tbl)
 {
-	return tbl == LightTables[0].data();
+	return tbl == FullyLitLightTable;
 }
 
 template <LightType Light, bool Transparent>

Source/lighting.cpp

@@ -24,6 +24,8 @@ Light Lights[MAXLIGHTS];
 std::array<uint8_t, MAXLIGHTS> ActiveLights;
 int ActiveLightCount;
 std::array<std::array<uint8_t, 256>, NumLightingLevels> LightTables;
+uint8_t *FullyLitLightTable = nullptr;
+uint8_t *FullyDarkLightTable = nullptr;
 std::array<uint8_t, 256> InfravisionTable;
 std::array<uint8_t, 256> StoneTable;
 std::array<uint8_t, 256> PauseTable;
@@ -345,6 +347,8 @@ void MakeLightTable()
 	}
 
 	LightTables[15] = {}; // Make last shade pitch black
+	FullyLitLightTable = LightTables[0].data();
+	FullyDarkLightTable = LightTables[LightsMax].data();
 
 	if (leveltype == DTYPE_HELL) {
 		// Blood wall lighting
@@ -361,14 +365,19 @@ void MakeLightTable()
 				lightTable[idx] = color;
 			}
 		}
+		FullyLitLightTable = nullptr; // A color map is used for the ceiling animation, so even fully lit tiles have a color map
 	} else if (IsAnyOf(leveltype, DTYPE_NEST, DTYPE_CRYPT)) {
 		// Make the lava fully bright
 		for (auto &lightTable : LightTables)
 			std::iota(lightTable.begin(), lightTable.begin() + 16, uint8_t { 0 });
 		LightTables[15][0] = 0;
 		std::fill_n(LightTables[15].begin() + 1, 15, 1);
+		FullyDarkLightTable = nullptr; // Tiles in Hellfire levels are never completely black
 	}
 
+	assert((FullyLitLightTable != nullptr) == (LightTables[0][0] == 0 && std::adjacent_find(LightTables[0].begin(), LightTables[0].end() - 1, [](auto x, auto y) { return (x + 1) != y; }) == LightTables[0].end() - 1));
+	assert((FullyDarkLightTable != nullptr) == (std::all_of(LightTables[LightsMax].begin(), LightTables[LightsMax].end(), [](auto x) { return x == 0; })));
+
 	LoadFileInMem("plrgfx\\infra.trn", InfravisionTable);
 	LoadFileInMem("plrgfx\\stone.trn", StoneTable);
 	LoadFileInMem("gendata\\pause.trn", PauseTable);

Source/lighting.h

@@ -49,6 +49,10 @@ extern std::array<uint8_t, MAXLIGHTS> ActiveLights;
 extern int ActiveLightCount;
 constexpr char LightsMax = 15;
 extern std::array<std::array<uint8_t, 256>, NumLightingLevels> LightTables;
+/** @brief Contains a pointer to a light table that is fully lit (no color mapping is required). Can be null in hell. */
+extern uint8_t *FullyLitLightTable;
+/** @brief Contains a pointer to a light table that is fully dark (every color result to 0/black). Can be null in hellfire levels. */
+extern uint8_t *FullyDarkLightTable;
 extern std::array<uint8_t, 256> InfravisionTable;
 extern std::array<uint8_t, 256> StoneTable;
 extern std::array<uint8_t, 256> PauseTable;