add basic lightning API

mods/ENVIRONMENT/lightning/init.lua

@@ -31,6 +31,7 @@ lightning = {
 	size = 100,
 	-- disable this to stop lightning mod from striking
 	auto = true,
+	on_strike_functions = {},
 }
 
 local rng = PcgRandom(32321123312123)
@@ -54,6 +55,18 @@ end
 
 minetest.register_globalstep(revertsky)
 
+-- lightning strike API
+
+-- See README.md
+--[[
+	lightning.register_on_strike(function(pos, pos2, objects)
+		-- code
+	end)
+]]
+function lightning.register_on_strike(func)
+	table.insert(lightning.on_strike_functions, func)
+end
+
 -- select a random strike point, midpoint
 local function choose_pos(pos)
 	if not pos then
@@ -94,7 +107,6 @@ local function choose_pos(pos)
 	return pos, pos2
 end
 
--- lightning strike API
 -- * pos: optional, if not given a random pos will be chosen
 -- * returns: bool - success if a strike happened
 function lightning.strike(pos)
@@ -108,21 +120,30 @@ function lightning.strike(pos)
 	if not pos then
 		return false
 	end
+	local objects = get_objects_inside_radius(pos2, 3.5)
+	if lightning.on_strike_functions then
+		for _, func in pairs(lightning.on_strike_functions) do
+			func(pos, pos2, objects)
+		end
+	end
+end
 
+
+
+lightning.register_on_strike(function(pos, pos2, objects)
+	local particle_pos = vector.offset(pos2, 0, (lightning.size / 2) + 0.5, 0)
+	local particle_size = lightning.size * 10
+	local time = 0.2
 	add_particlespawner({
 		amount = 1,
-		time = 0.2,
+		time = time,
 		-- make it hit the top of a block exactly with the bottom
-		minpos = {x = pos2.x, y = pos2.y + (lightning.size / 2) + 1/2, z = pos2.z },
-		maxpos = {x = pos2.x, y = pos2.y + (lightning.size / 2) + 1/2, z = pos2.z },
-		minvel = {x = 0, y = 0, z = 0},
-		maxvel = {x = 0, y = 0, z = 0},
-		minacc = {x = 0, y = 0, z = 0},
-		maxacc = {x = 0, y = 0, z = 0},
-		minexptime = 0.2,
-		maxexptime = 0.2,
-		minsize = lightning.size * 10,
-		maxsize = lightning.size * 10,
+		minpos = particle_pos,
+		maxpos = particle_pos,
+		minexptime = time,
+		maxexptime = time,
+		minsize = particle_size,
+		maxsize = particle_size,
 		collisiondetection = true,
 		vertical = true,
 		-- to make it appear hitting the node that will get set on fire, make sure
@@ -135,10 +156,7 @@ function lightning.strike(pos)
 	sound_play({ name = "lightning_thunder", gain = 10 }, { pos = pos, max_hear_distance = 500 }, true)
 
 	-- damage nearby objects, transform mobs
-    -- TODO: use an API insteed of hardcoding this behaviour
-	local objs = get_objects_inside_radius(pos2, 3.5)
-	for o=1, #objs do
-		local obj = objs[o]
+	for _, obj in pairs(objects) do
 		local lua = obj:get_luaentity()
 		-- pig → zombie pigman (no damage)
 		if lua and lua.name == "mobs_mc:pig" then
@@ -223,8 +241,7 @@ function lightning.strike(pos)
 			end
 		end
 	end
-
-end
+end)
 
 -- if other mods disable auto lightning during initialization, don't trigger the first lightning.
 after(5, function(dtime)