4 files changed, 86 insertions, 14 deletions

diff --git a/Server/Plugins/APIDump/APIDesc.lua b/Server/Plugins/APIDump/APIDesc.lua
index 3a4e81f0c..dafe98619 100644
--- a/Server/Plugins/APIDump/APIDesc.lua
+++ b/Server/Plugins/APIDump/APIDesc.lua
@@ -294,6 +294,24 @@ return
 					},
 					Notes = "Returns whether the specified block type is solid.",
 				},
+				IsSkylightDispersant =
+				{
+					IsStatic = true,
+					Params =
+					{
+						{
+							Name = "BlockType",
+							Type = "number",
+						},
+					},
+					Returns =
+					{
+						{
+							Type = "boolean",
+						},
+					},
+					Notes = "Returns true if skylight is impeded by passage through a block of the specified type.",
+				},
 				IsTransparent =
 				{
 					IsStatic = true,
diff --git a/src/BlockInfo.cpp b/src/BlockInfo.cpp
index a6178ec55..3021c5efe 100644
--- a/src/BlockInfo.cpp
+++ b/src/BlockInfo.cpp
@@ -100,7 +100,6 @@ cBlockInfo::cBlockInfoArray::cBlockInfoArray()
 	Info[E_BLOCK_HEAD                         ].m_SpreadLightFalloff = 1;
 	Info[E_BLOCK_HEAVY_WEIGHTED_PRESSURE_PLATE].m_SpreadLightFalloff = 1;
 	Info[E_BLOCK_HOPPER                       ].m_SpreadLightFalloff = 1;
-	Info[E_BLOCK_ICE                          ].m_SpreadLightFalloff = 1;
 	Info[E_BLOCK_INACTIVE_COMPARATOR          ].m_SpreadLightFalloff = 1;
 	Info[E_BLOCK_INVERTED_DAYLIGHT_SENSOR     ].m_SpreadLightFalloff = 1;
 	Info[E_BLOCK_IRON_BARS                    ].m_SpreadLightFalloff = 1;
@@ -161,17 +160,42 @@ cBlockInfo::cBlockInfoArray::cBlockInfoArray()
 	Info[E_BLOCK_WOODEN_PRESSURE_PLATE        ].m_SpreadLightFalloff = 1;
 	Info[E_BLOCK_WOODEN_SLAB                  ].m_SpreadLightFalloff = 1;
 
-	// Light in water and lava dissapears faster:
-	Info[E_BLOCK_LAVA                         ].m_SpreadLightFalloff = 3;
-	Info[E_BLOCK_STATIONARY_LAVA              ].m_SpreadLightFalloff = 3;
+	// Light in ice and water dissapears faster:
+	Info[E_BLOCK_ICE                          ].m_SpreadLightFalloff = 3;
 	Info[E_BLOCK_STATIONARY_WATER             ].m_SpreadLightFalloff = 3;
 	Info[E_BLOCK_WATER                        ].m_SpreadLightFalloff = 3;
 
+	// Light does not pass through these blocks at all:
+	Info[E_BLOCK_ACACIA_WOOD_STAIRS           ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_BIRCH_WOOD_STAIRS            ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_BRICK_STAIRS                 ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_COBBLESTONE_STAIRS           ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_DARK_OAK_WOOD_STAIRS         ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_DOUBLE_RED_SANDSTONE_SLAB    ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_DOUBLE_STONE_SLAB            ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_DOUBLE_WOODEN_SLAB           ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_FARMLAND                     ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_JUNGLE_WOOD_STAIRS           ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_NETHER_BRICK_STAIRS          ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_OAK_WOOD_STAIRS              ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_PURPUR_DOUBLE_SLAB           ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_PURPUR_SLAB                  ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_PURPUR_STAIRS                ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_QUARTZ_STAIRS                ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_RED_SANDSTONE_SLAB           ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_RED_SANDSTONE_STAIRS         ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_SANDSTONE_STAIRS             ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_SPRUCE_WOOD_STAIRS           ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_STONE_BRICK_STAIRS           ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_STONE_SLAB                   ].m_SpreadLightFalloff = 15;
+	Info[E_BLOCK_WOODEN_SLAB                  ].m_SpreadLightFalloff = 15;
 
 	// Transparent blocks
+
 	Info[E_BLOCK_ACACIA_DOOR                  ].m_Transparent = true;
 	Info[E_BLOCK_ACACIA_FENCE                 ].m_Transparent = true;
 	Info[E_BLOCK_ACACIA_FENCE_GATE            ].m_Transparent = true;
+	Info[E_BLOCK_ACACIA_WOOD_STAIRS           ].m_Transparent = true;
 	Info[E_BLOCK_ACTIVATOR_RAIL               ].m_Transparent = true;
 	Info[E_BLOCK_ACTIVE_COMPARATOR            ].m_Transparent = true;
 	Info[E_BLOCK_AIR                          ].m_Transparent = true;
@@ -183,38 +207,44 @@ cBlockInfo::cBlockInfoArray::cBlockInfoArray()
 	Info[E_BLOCK_BIRCH_DOOR                   ].m_Transparent = true;
 	Info[E_BLOCK_BIRCH_FENCE                  ].m_Transparent = true;
 	Info[E_BLOCK_BIRCH_FENCE_GATE             ].m_Transparent = true;
+	Info[E_BLOCK_BIRCH_WOOD_STAIRS            ].m_Transparent = true;
 	Info[E_BLOCK_BLACK_SHULKER_BOX            ].m_Transparent = true;
 	Info[E_BLOCK_BLOCK_OF_REDSTONE            ].m_Transparent = true;
 	Info[E_BLOCK_BLUE_SHULKER_BOX             ].m_Transparent = true;
+	Info[E_BLOCK_BREWING_STAND                ].m_Transparent = true;
+	Info[E_BLOCK_BRICK_STAIRS                 ].m_Transparent = true;
 	Info[E_BLOCK_BROWN_MUSHROOM               ].m_Transparent = true;
 	Info[E_BLOCK_BROWN_SHULKER_BOX            ].m_Transparent = true;
-	Info[E_BLOCK_BREWING_STAND                ].m_Transparent = true;
 	Info[E_BLOCK_CACTUS                       ].m_Transparent = true;
 	Info[E_BLOCK_CAKE                         ].m_Transparent = true;
 	Info[E_BLOCK_CARPET                       ].m_Transparent = true;
 	Info[E_BLOCK_CARROTS                      ].m_Transparent = true;
 	Info[E_BLOCK_CAULDRON                     ].m_Transparent = true;
 	Info[E_BLOCK_CHEST                        ].m_Transparent = true;
+	Info[E_BLOCK_COBBLESTONE_STAIRS           ].m_Transparent = true;
 	Info[E_BLOCK_COBBLESTONE_WALL             ].m_Transparent = true;
-	Info[E_BLOCK_COCOA_POD                    ].m_Transparent = true;
 	Info[E_BLOCK_COBWEB                       ].m_Transparent = true;
+	Info[E_BLOCK_COCOA_POD                    ].m_Transparent = true;
 	Info[E_BLOCK_CROPS                        ].m_Transparent = true;
 	Info[E_BLOCK_CYAN_SHULKER_BOX             ].m_Transparent = true;
 	Info[E_BLOCK_DANDELION                    ].m_Transparent = true;
 	Info[E_BLOCK_DARK_OAK_DOOR                ].m_Transparent = true;
 	Info[E_BLOCK_DARK_OAK_FENCE               ].m_Transparent = true;
 	Info[E_BLOCK_DARK_OAK_FENCE_GATE          ].m_Transparent = true;
+	Info[E_BLOCK_DARK_OAK_WOOD_STAIRS         ].m_Transparent = true;
 	Info[E_BLOCK_DAYLIGHT_SENSOR              ].m_Transparent = true;
 	Info[E_BLOCK_DEAD_BUSH                    ].m_Transparent = true;
 	Info[E_BLOCK_DETECTOR_RAIL                ].m_Transparent = true;
+	Info[E_BLOCK_DOUBLE_RED_SANDSTONE_SLAB    ].m_Transparent = true;
+	Info[E_BLOCK_DOUBLE_STONE_SLAB            ].m_Transparent = true;
+	Info[E_BLOCK_DOUBLE_WOODEN_SLAB           ].m_Transparent = true;
 	Info[E_BLOCK_DRAGON_EGG                   ].m_Transparent = true;
 	Info[E_BLOCK_ENCHANTMENT_TABLE            ].m_Transparent = true;
-	Info[E_BLOCK_ENDER_CHEST                  ].m_Transparent = true;
 	Info[E_BLOCK_END_PORTAL                   ].m_Transparent = true;
 	Info[E_BLOCK_END_PORTAL_FRAME             ].m_Transparent = true;
+	Info[E_BLOCK_ENDER_CHEST                  ].m_Transparent = true;
 	Info[E_BLOCK_FARMLAND                     ].m_Transparent = true;
 	Info[E_BLOCK_FENCE                        ].m_Transparent = true;
-	Info[E_BLOCK_OAK_FENCE_GATE               ].m_Transparent = true;
 	Info[E_BLOCK_FIRE                         ].m_Transparent = true;
 	Info[E_BLOCK_FLOWER                       ].m_Transparent = true;
 	Info[E_BLOCK_FLOWER_POT                   ].m_Transparent = true;
@@ -234,23 +264,28 @@ cBlockInfo::cBlockInfoArray::cBlockInfoArray()
 	Info[E_BLOCK_JUNGLE_DOOR                  ].m_Transparent = true;
 	Info[E_BLOCK_JUNGLE_FENCE                 ].m_Transparent = true;
 	Info[E_BLOCK_JUNGLE_FENCE_GATE            ].m_Transparent = true;
+	Info[E_BLOCK_JUNGLE_WOOD_STAIRS           ].m_Transparent = true;
 	Info[E_BLOCK_LADDER                       ].m_Transparent = true;
 	Info[E_BLOCK_LAVA                         ].m_Transparent = true;
 	Info[E_BLOCK_LEAVES                       ].m_Transparent = true;
 	Info[E_BLOCK_LEVER                        ].m_Transparent = true;
-	Info[E_BLOCK_LILY_PAD                     ].m_Transparent = true;
 	Info[E_BLOCK_LIGHT_BLUE_SHULKER_BOX       ].m_Transparent = true;
 	Info[E_BLOCK_LIGHT_GRAY_SHULKER_BOX       ].m_Transparent = true;
 	Info[E_BLOCK_LIGHT_WEIGHTED_PRESSURE_PLATE].m_Transparent = true;
+	Info[E_BLOCK_LILY_PAD                     ].m_Transparent = true;
 	Info[E_BLOCK_LIME_SHULKER_BOX             ].m_Transparent = true;
 	Info[E_BLOCK_LIT_FURNACE                  ].m_Transparent = true;
 	Info[E_BLOCK_MAGENTA_SHULKER_BOX          ].m_Transparent = true;
 	Info[E_BLOCK_MELON_STEM                   ].m_Transparent = true;
 	Info[E_BLOCK_MOB_SPAWNER                  ].m_Transparent = true;
 	Info[E_BLOCK_NETHER_BRICK_FENCE           ].m_Transparent = true;
+	Info[E_BLOCK_NETHER_BRICK_STAIRS          ].m_Transparent = true;
 	Info[E_BLOCK_NETHER_PORTAL                ].m_Transparent = true;
 	Info[E_BLOCK_NETHER_WART                  ].m_Transparent = true;
 	Info[E_BLOCK_NEW_LEAVES                   ].m_Transparent = true;
+	Info[E_BLOCK_OAK_DOOR                     ].m_Transparent = true;
+	Info[E_BLOCK_OAK_FENCE_GATE               ].m_Transparent = true;
+	Info[E_BLOCK_OAK_WOOD_STAIRS              ].m_Transparent = true;
 	Info[E_BLOCK_ORANGE_SHULKER_BOX           ].m_Transparent = true;
 	Info[E_BLOCK_PINK_SHULKER_BOX             ].m_Transparent = true;
 	Info[E_BLOCK_PISTON                       ].m_Transparent = true;
@@ -260,10 +295,14 @@ cBlockInfo::cBlockInfoArray::cBlockInfoArray()
 	Info[E_BLOCK_POWERED_RAIL                 ].m_Transparent = true;
 	Info[E_BLOCK_PUMPKIN_STEM                 ].m_Transparent = true;
 	Info[E_BLOCK_PURPLE_SHULKER_BOX           ].m_Transparent = true;
+	Info[E_BLOCK_PURPUR_DOUBLE_SLAB           ].m_Transparent = true;
 	Info[E_BLOCK_PURPUR_SLAB                  ].m_Transparent = true;
+	Info[E_BLOCK_PURPUR_STAIRS                ].m_Transparent = true;
+	Info[E_BLOCK_QUARTZ_STAIRS                ].m_Transparent = true;
 	Info[E_BLOCK_RAIL                         ].m_Transparent = true;
 	Info[E_BLOCK_RED_MUSHROOM                 ].m_Transparent = true;
 	Info[E_BLOCK_RED_SANDSTONE_SLAB           ].m_Transparent = true;
+	Info[E_BLOCK_RED_SANDSTONE_STAIRS         ].m_Transparent = true;
 	Info[E_BLOCK_RED_SHULKER_BOX              ].m_Transparent = true;
 	Info[E_BLOCK_REDSTONE_ORE_GLOWING         ].m_Transparent = true;
 	Info[E_BLOCK_REDSTONE_REPEATER_OFF        ].m_Transparent = true;
@@ -271,20 +310,22 @@ cBlockInfo::cBlockInfoArray::cBlockInfoArray()
 	Info[E_BLOCK_REDSTONE_TORCH_OFF           ].m_Transparent = true;
 	Info[E_BLOCK_REDSTONE_TORCH_ON            ].m_Transparent = true;
 	Info[E_BLOCK_REDSTONE_WIRE                ].m_Transparent = true;
+	Info[E_BLOCK_SANDSTONE_STAIRS             ].m_Transparent = true;
 	Info[E_BLOCK_SAPLING                      ].m_Transparent = true;
 	Info[E_BLOCK_SIGN_POST                    ].m_Transparent = true;
 	Info[E_BLOCK_SPRUCE_DOOR                  ].m_Transparent = true;
 	Info[E_BLOCK_SPRUCE_FENCE                 ].m_Transparent = true;
 	Info[E_BLOCK_SPRUCE_FENCE_GATE            ].m_Transparent = true;
+	Info[E_BLOCK_SPRUCE_WOOD_STAIRS           ].m_Transparent = true;
 	Info[E_BLOCK_STAINED_GLASS                ].m_Transparent = true;
 	Info[E_BLOCK_STAINED_GLASS_PANE           ].m_Transparent = true;
+	Info[E_BLOCK_STANDING_BANNER              ].m_Transparent = true;
 	Info[E_BLOCK_STATIONARY_LAVA              ].m_Transparent = true;
 	Info[E_BLOCK_STATIONARY_WATER             ].m_Transparent = true;
-	Info[E_BLOCK_STANDING_BANNER              ].m_Transparent = true;
 	Info[E_BLOCK_STICKY_PISTON                ].m_Transparent = true;
+	Info[E_BLOCK_STONE_BRICK_STAIRS           ].m_Transparent = true;
 	Info[E_BLOCK_STONE_BUTTON                 ].m_Transparent = true;
 	Info[E_BLOCK_STONE_PRESSURE_PLATE         ].m_Transparent = true;
-	Info[E_BLOCK_STONE_SLAB                   ].m_Transparent = true;
 	Info[E_BLOCK_SUGARCANE                    ].m_Transparent = true;
 	Info[E_BLOCK_TALL_GRASS                   ].m_Transparent = true;
 	Info[E_BLOCK_TORCH                        ].m_Transparent = true;
@@ -298,12 +339,16 @@ cBlockInfo::cBlockInfoArray::cBlockInfoArray()
 	Info[E_BLOCK_WATER                        ].m_Transparent = true;
 	Info[E_BLOCK_WHITE_SHULKER_BOX            ].m_Transparent = true;
 	Info[E_BLOCK_WOODEN_BUTTON                ].m_Transparent = true;
-	Info[E_BLOCK_OAK_DOOR                     ].m_Transparent = true;
 	Info[E_BLOCK_WOODEN_PRESSURE_PLATE        ].m_Transparent = true;
 	Info[E_BLOCK_WOODEN_SLAB                  ].m_Transparent = true;
 	Info[E_BLOCK_YELLOW_SHULKER_BOX           ].m_Transparent = true;
 
 
+	// Skylight dispersant blocks:
+	Info[E_BLOCK_COBWEB                       ].m_IsSkylightDispersant = true;
+	Info[E_BLOCK_LEAVES                       ].m_IsSkylightDispersant = true;
+
+
 	// One hit break blocks:
 	Info[E_BLOCK_ACTIVE_COMPARATOR            ].m_OneHitDig = true;
 	Info[E_BLOCK_BEETROOTS                    ].m_OneHitDig = true;
diff --git a/src/BlockInfo.h b/src/BlockInfo.h
index 1ba818cb3..fd8408638 100644
--- a/src/BlockInfo.h
+++ b/src/BlockInfo.h
@@ -28,7 +28,7 @@ public:
 	/** How much light do the blocks consume? */
 	NIBBLETYPE m_SpreadLightFalloff;
 
-	/** Is a block completely transparent? (light doesn't get decreased(?)) */
+	/** Is a block transparent? (https://minecraft.gamepedia.com/Opacity) */
 	bool m_Transparent;
 
 	/** Is a block destroyed after a single hit? */
@@ -37,6 +37,9 @@ public:
 	/** Can a piston break this block? */
 	bool m_PistonBreakable;
 
+	/** Does a block disperse sky light? (only relevant for transparent blocks) */
+	bool m_IsSkylightDispersant;
+
 	/** Can this block hold snow atop? */
 	bool m_IsSnowable;
 
@@ -76,6 +79,10 @@ public:
 	inline static bool IsTransparent              (BLOCKTYPE a_Type) { return Get(a_Type).m_Transparent;         }
 	inline static bool IsOneHitDig                (BLOCKTYPE a_Type) { return Get(a_Type).m_OneHitDig;           }
 	inline static bool IsPistonBreakable          (BLOCKTYPE a_Type) { return Get(a_Type).m_PistonBreakable;     }
+	inline static bool IsSkylightDispersant       (BLOCKTYPE a_Type)
+	{
+		return ((Get(a_Type).m_IsSkylightDispersant) || (Get(a_Type).m_SpreadLightFalloff > 1));
+	}
 	inline static bool IsSnowable                 (BLOCKTYPE a_Type) { return Get(a_Type).m_IsSnowable;          }
 	inline static bool IsSolid                    (BLOCKTYPE a_Type) { return Get(a_Type).m_IsSolid;             }
 	inline static bool IsUseableBySpectator       (BLOCKTYPE a_Type) { return Get(a_Type).m_UseableBySpectator;  }
@@ -95,6 +102,7 @@ public:
 		, m_Transparent(false)
 		, m_OneHitDig(false)
 		, m_PistonBreakable(false)
+		, m_IsSkylightDispersant(false)
 		, m_IsSnowable(false)
 		, m_IsSolid(true)
 		, m_UseableBySpectator(false)
diff --git a/src/LightingThread.cpp b/src/LightingThread.cpp
index df1a802a5..302a7ba01 100644
--- a/src/LightingThread.cpp
+++ b/src/LightingThread.cpp
@@ -378,7 +378,8 @@ void cLightingThread::PrepareSkyLight(void)
 			ASSERT(Current < cChunkDef::Height);
 			while (
 				(Current >= 0) &&
-				cBlockInfo::IsTransparent(m_BlockTypes[idx + Current * BlocksPerYLayer])
+				cBlockInfo::IsTransparent(m_BlockTypes[idx + Current * BlocksPerYLayer]) &&
+				!cBlockInfo::IsSkylightDispersant(m_BlockTypes[idx + Current * BlocksPerYLayer])
 			)
 			{
 				Current -= 1;  // Sunlight goes down unchanged through this block