From bf9c990760ec595d3b3bda7a40a7bae55fa2a352 Mon Sep 17 00:00:00 2001
From: Wuzzy <almikes@aol.com>
Date: Fri, 26 May 2017 21:25:25 +0200
Subject: [PATCH] New vines growth algorithm (WIP)

---
 mods/ITEMS/mcl_core/functions.lua | 86 ++++++++++++++++++++++++++++---
 1 file changed, 78 insertions(+), 8 deletions(-)

diff --git a/mods/ITEMS/mcl_core/functions.lua b/mods/ITEMS/mcl_core/functions.lua
index 1d3723f93..96489931e 100644
--- a/mods/ITEMS/mcl_core/functions.lua
+++ b/mods/ITEMS/mcl_core/functions.lua
@@ -759,19 +759,89 @@ minetest.register_abm({
 minetest.register_abm({
 	label = "Vines growth",
 	nodenames = {"mcl_core:vine"},
-	interval = 80,
-	chance = 5,
+	interval = 47,
+	chance = 4,
 	action = function(pos, node, active_object_count, active_object_count_wider)
-		local newpos = {x=pos.x, y=pos.y-1, z=pos.z}
-		local n = minetest.get_node(newpos)
-		if n.name == "air" then
-			local walldir = node.param2
-			minetest.add_node(newpos, {name = "mcl_core:vine", param2 = walldir})
+
+		local neighbor_offsets = {
+			{ x=1, y=0, z=0 },
+			{ x=-1, y=0, z=0 },
+			{ x=0, y=0, z=1 },
+			{ x=0, y=0, z=-1 },
+		}
+
+		-- Add vines below pos (if empty)
+		local spread_down = function(pos, node)
+			local down = vector.add(pos, {x=0, y=-1, z=0})
+			if minetest.get_node(down).name == "air" then
+				minetest.add_node(down, {name = "mcl_core:vine", param2 = node.param2})
+			end
 		end
+
+		-- Add vines above pos if it is backed up
+		local spread_up = function(pos, node)
+			local up = vector.add(pos, {x=0, y=1, z=0})
+			if minetest.get_node(up).name == "air" then
+				local backup_dir = minetest.facedir_to_dir(node.param2)
+				local backup = vector.add(up, backup_dir)
+				local backupnodename = minetest.get_node(backup).name
+				minetest.log("error" , minetest.pos_to_string(backup))
+
+				-- Check if the block above is supported
+				if mcl_core.supports_vines(backupnodename) then
+					minetest.add_node(up, {name = "mcl_core:vine", param2 = node.param2})
+				end
+			end
+		end
+
+		-- Try to spread vines from the 4 horizontal neighbors
+		local spread_neighbors = function(pos, node, spread_dir)
+			for n=1, #neighbor_offsets do
+				if math.random(1,2) == 1 then
+					local neighbor = vector.add(pos, neighbor_offsets[n])
+					local neighbornode = minetest.get_node(neighbor)
+					if neighbornode.name == "mcl_core:vine" then
+						if spread_dir == "up" then
+							spread_up(neighbor, neighbornode)
+						elseif spread_dir == "down" then
+							spread_down(neighbor, neighbornode)
+						end
+					end
+				end
+			end
+		end
+
+		-- Spread down
+		local down = {x=pos.x, y=pos.y-1, z=pos.z}
+		local down_node = minetest.get_node(down)
+		if down_node.name == "air" then
+			spread_neighbors(pos, node, "down")
+		elseif down_node.name == "mcl_core:vine" then
+			spread_neighbors(down, down_node, "down")
+		end
+
+		-- Spread up
+		local up = {x=pos.x, y=pos.y+1, z=pos.z}
+		local up_node = minetest.get_node(up)
+		if up_node.name == "air" then
+			local vines_in_area = minetest.find_nodes_in_area({x=pos.x-4, y=pos.y-1, z=pos.z-4}, {x=pos.x+4, y=pos.y+1, z=pos.z+4}, "mcl_core:vine")
+			-- Less then 4 vines blocks around the ticked vines block (remember the ticked block is counted by above function as well)
+			if #vines_in_area < 5 then
+				spread_neighbors(pos, node, "up")
+			end
+		end
+
+		-- TODO: Spread horizontally
+
 	end
 })
 
-
+-- Returns true of the node supports vines
+mcl_core.supports_vines = function(nodename)
+	local def = minetest.registered_nodes[nodename]
+	-- Rules: 1) walkable 2) full cube
+	return def.walkable and ((not def.node_box) or def.node_box.type == "regular")
+end
 
 -- Leaf Decay