throwing/tnt_arrow.lua

minetest.register_craftitem("throwing:arrow_tnt", {
	description = "TNT arrow",
	inventory_image = "throwing_arrow_tnt.png",
})

minetest.register_node("throwing:arrow_tnt_box", {
	drawtype = "nodebox",
	node_box = {
		type = "fixed",
		fixed = {
			-- Shaft
			{-6.5/17, -1.5/17, -1.5/17, 6.5/17, 1.5/17, 1.5/17},
			--Spitze
			{-4.5/17, 2.5/17, 2.5/17, -3.5/17, -2.5/17, -2.5/17},
			{-8.5/17, 0.5/17, 0.5/17, -6.5/17, -0.5/17, -0.5/17},
			--Federn
			{6.5/17, 1.5/17, 1.5/17, 7.5/17, 2.5/17, 2.5/17},
			{7.5/17, -2.5/17, 2.5/17, 6.5/17, -1.5/17, 1.5/17},
			{7.5/17, 2.5/17, -2.5/17, 6.5/17, 1.5/17, -1.5/17},
			{6.5/17, -1.5/17, -1.5/17, 7.5/17, -2.5/17, -2.5/17},
			
			{7.5/17, 2.5/17, 2.5/17, 8.5/17, 3.5/17, 3.5/17},
			{8.5/17, -3.5/17, 3.5/17, 7.5/17, -2.5/17, 2.5/17},
			{8.5/17, 3.5/17, -3.5/17, 7.5/17, 2.5/17, -2.5/17},
			{7.5/17, -2.5/17, -2.5/17, 8.5/17, -3.5/17, -3.5/17},
		}
	},
	tiles = {"throwing_arrow_tnt.png", "throwing_arrow_tnt.png", "throwing_arrow_tnt_back.png", "throwing_arrow_tnt_front.png", "throwing_arrow_tnt_2.png", "throwing_arrow_tnt.png"},
	groups = {not_in_creative_inventory=1},
})

local THROWING_ARROW_ENTITY={
	physical = false,
	timer=0,
	visual = "wielditem",
	visual_size = {x=0.1, y=0.1},
	textures = {"throwing:arrow_tnt_box"},
	lastpos={},
	collisionbox = {0,0,0,0,0,0},
}

-- TNT functions copied, would be nice to directly call them through an API...

-- loss probabilities array (one in X will be lost)
local loss_prob = {}

loss_prob["default:cobble"] = 3
loss_prob["default:dirt"] = 4

local radius = tonumber(minetest.setting_get("tnt_radius") or 3)

-- Fill a list with data for content IDs, after all nodes are registered
local cid_data = {}
minetest.after(0, function()
	for name, def in pairs(minetest.registered_nodes) do
		cid_data[minetest.get_content_id(name)] = {
			name = name,
			drops = def.drops,
			flammable = def.groups.flammable,
		}
	end
end)

local function rand_pos(center, pos, radius)
	pos.x = center.x + math.random(-radius, radius)
	pos.z = center.z + math.random(-radius, radius)
end

local function eject_drops(drops, pos, radius)
	local drop_pos = vector.new(pos)
	for _, item in pairs(drops) do
		local count = item:get_count()
		local max = item:get_stack_max()
		if count > max then
			item:set_count(max)
		end
		while count > 0 do
			if count < max then
				item:set_count(count)
			end
			rand_pos(pos, drop_pos, radius)
			local obj = minetest.add_item(drop_pos, item)
			if obj then
				obj:get_luaentity().collect = true
				obj:setacceleration({x=0, y=-10, z=0})
				obj:setvelocity({x=math.random(-3, 3), y=10,
						z=math.random(-3, 3)})
			end
			count = count - max
		end
	end
end

local function add_drop(drops, item)
	item = ItemStack(item)
	local name = item:get_name()
	if loss_prob[name] ~= nil and math.random(1, loss_prob[name]) == 1 then
		return
	end

	local drop = drops[name]
	if drop == nil then
		drops[name] = item
	else
		drop:set_count(drop:get_count() + item:get_count())
	end
end

local fire_node = {name="fire:basic_flame"}

local function destroy(drops, pos, cid)
	if minetest.is_protected(pos, "") then
		return
	end
	local def = cid_data[cid]
	if def and def.flammable then
		minetest.set_node(pos, fire_node)
	else
		minetest.dig_node(pos)
		if def then
			local node_drops = minetest.get_node_drops(def.name, "")
			for _, item in ipairs(node_drops) do
				add_drop(drops, item)
			end
		end
	end
end


local function calc_velocity(pos1, pos2, old_vel, power)
	local vel = vector.direction(pos1, pos2)
	vel = vector.normalize(vel)
	vel = vector.multiply(vel, power)

	-- Divide by distance
	local dist = vector.distance(pos1, pos2)
	dist = math.max(dist, 1)
	vel = vector.divide(vel, dist)

	-- Add old velocity
	vel = vector.add(vel, old_vel)
	return vel
end

local function entity_physics(pos, radius)
	-- Make the damage radius larger than the destruction radius
	radius = radius * 2
	local objs = minetest.get_objects_inside_radius(pos, radius)
	for _, obj in pairs(objs) do
		local obj_pos = obj:getpos()
		local obj_vel = obj:getvelocity()
		local dist = math.max(1, vector.distance(pos, obj_pos))

		if obj_vel ~= nil then
			obj:setvelocity(calc_velocity(pos, obj_pos,
					obj_vel, radius * 10))
		end

		local damage = (5 / dist) * radius
		obj:set_hp(obj:get_hp() - damage)
	end
end

local function add_effects(pos, radius)
	minetest.add_particlespawner({
		amount = 128,
		time = 1,
		minpos = vector.subtract(pos, radius / 2),
		maxpos = vector.add(pos, radius / 2),
		minvel = {x=-20, y=-20, z=-20},
		maxvel = {x=20,  y=20,  z=20},
		minacc = vector.new(),
		maxacc = vector.new(),
		minexptime = 1,
		maxexptime = 3,
		minsize = 8,
		maxsize = 16,
		texture = "tnt_smoke.png",
	})
end


local function explode(pos, radius)
	local pos = vector.round(pos)
	local vm = VoxelManip()
	local pr = PseudoRandom(os.time())
	local p1 = vector.subtract(pos, radius)
	local p2 = vector.add(pos, radius)
	local minp, maxp = vm:read_from_map(p1, p2)
	local a = VoxelArea:new({MinEdge = minp, MaxEdge = maxp})
	local data = vm:get_data()

	local drops = {}
	local p = {}

	local c_air = minetest.get_content_id("air")
	local c_tnt = minetest.get_content_id("tnt:tnt")
	local c_tnt_burning = minetest.get_content_id("tnt:tnt_burning")
	local c_gunpowder = minetest.get_content_id("tnt:gunpowder")
	local c_gunpowder_burning = minetest.get_content_id("tnt:gunpowder_burning")
	local c_boom = minetest.get_content_id("tnt:boom")
	local c_fire = minetest.get_content_id("fire:basic_flame")

	for z = -radius, radius do
	for y = -radius, radius do
	local vi = a:index(pos.x + (-radius), pos.y + y, pos.z + z)
	for x = -radius, radius do
		if (x * x) + (y * y) + (z * z) <=
				(radius * radius) + pr:next(-radius, radius) then
			local cid = data[vi]
			p.x = pos.x + x
			p.y = pos.y + y
			p.z = pos.z + z
			if cid == c_tnt or cid == c_gunpowder then
				burn(p)
			elseif cid ~= c_tnt_burning and
					cid ~= c_gunpowder_burning and
					cid ~= c_air and
					cid ~= c_fire and
					cid ~= c_boom then
				destroy(drops, p, cid)
			end
		end
		vi = vi + 1
	end
	end
	end

	return drops
end


local function boom(pos)
	minetest.sound_play("tnt_explode", {pos=pos, gain=1.5, max_hear_distance=2*64})
	minetest.set_node(pos, {name="tnt:boom"})
	minetest.get_node_timer(pos):start(0.5)

	local drops = explode(pos, radius)
	entity_physics(pos, radius)
	eject_drops(drops, pos, radius)
	add_effects(pos, radius)
end

-- Back to the arrow

THROWING_ARROW_ENTITY.on_step = function(self, dtime)
	self.timer=self.timer+dtime
	local pos = self.object:getpos()
	local node = minetest.get_node(pos)

	if self.timer>0.2 then
		local objs = minetest.get_objects_inside_radius({x=pos.x,y=pos.y,z=pos.z}, 2)
		for k, obj in pairs(objs) do
			if obj:get_luaentity() ~= nil then
				if obj:get_luaentity().name ~= "throwing:arrow_tnt_entity" and obj:get_luaentity().name ~= "__builtin:item" then
					self.object:remove()
					boom(pos)
				end
			end
		end
	end

	if self.lastpos.x~=nil then
		if node.name ~= "air" then
			self.object:remove()
			boom(self.lastpos)
		end
	end
	self.lastpos={x=pos.x, y=pos.y, z=pos.z}
end

minetest.register_entity("throwing:arrow_tnt_entity", THROWING_ARROW_ENTITY)

minetest.register_craft({
	output = 'throwing:arrow_tnt',
	recipe = {
		{'default:stick', 'tnt:tnt', 'default:bronze_ingot'},
	}
})

minetest.register_craft({
	output = 'throwing:arrow_tnt',
	recipe = {
		{'default:bronze_ingot', 'tnt:tnt', 'default:stick'},
	}
})