The_End/mods/items/gunpowder_barrels/barrel_entity.lua

local entity_definition = {
	initial_properties = {
		physical = true,
		collide_with_objects = false,
		weight = 5,
		collisionbox = {-0.2, -0.3, -0.2, 0.2, 0.1, 0.2},
		selectionbox = {-0.4, -0.3, -0.4, 0.4, 0.3, 0.4},
		visual = "sprite",
		textures = {"gunpowder_barrels_barrel.png"},
	},
	falling_timer = -1,
	life_timer = 0,
	fuse = nil,
}

entity_definition.get_staticdata = function(self)
	return ""
end

entity_definition.explode = gunpowder_barrels.explode

entity_definition.on_activate = function(self, staticdata)
	if staticdata == "" --place
	then
		self.old_velocity = {x = 0, y = 0, z = 0}
	else --throw
		local vel = minetest.deserialize(staticdata)

		--make sure staticdata is a serialized vector
		assert(vel.x and vel.y and vel.z)

		--apply velocity
		self.object:setvelocity(vel)
		self.old_velocity = vel
		--light fuse
		self:start_fuse(math.random() * 100 + 100)
	end

	--falling physics
	self.object:setacceleration({x = 0, y = -9, z = 0})

	self.object:set_armor_groups({punch_operable = 1})
end

entity_definition.start_fuse = function(self, time)
	self.fuse_handle = minetest.sound_play(
		"gunpowder_barrels_fuse",
		{
			object = self.object,
			gain = 1,
			loop = true,
			pitch = 1.5,
		})
	self.fuse = time
end

entity_definition.on_step = function(self)
	if self.life_timer == 10
	then
		self.object:set_properties({collide_with_objects = true})
	end
	self.life_timer = self.life_timer + 1

	local vel = self.object:getvelocity()


	local pos = self.object:get_pos()

	if self.fuse
	then
		if self.fuse > 0
		then
			self.fuse = self.fuse - 1

			local particlepos = {x = pos.x, y = pos.y + 0.5, z = pos.z}
			local parent, bone, offset = self.object:get_attach()


			if parent
			then

				particlepos.x = particlepos.x + offset.x / 10
				particlepos.y = particlepos.y + offset.y / 10
				particlepos.z = particlepos.z + offset.z / 10
			end


			minetest.add_particle(
			{
				pos = particlepos,
				velocity = {x = 0, y = 1, z = 0},
				expirationtime = math.random() * 0.3,
				texture = "gunpowder_barrels_spark.png",
				glow = 14,
			})
		else
			self:explode()
		end
	end


	--float on water
	do
		pos.y = pos.y + 0.4

		local node_name = minetest.get_node(pos).name
		if minetest.get_item_group(node_name, "water") > 0
		then
			self.object:setacceleration({x = 0, y = 7, z = 0})
			vel = {x = vel.x * 0.7, y = vel.y * 0.9, z = vel.z * 0.7}
			self.object:setvelocity(vel)
			self.falling_timer = 0
			self.fuse = nil
			return
		else
			local downpos = {x = pos.x, y = pos.y - 1, z = pos.z}
			node_name = minetest.get_node(downpos).name
			if minetest.get_item_group(node_name, "water") > 0
			then
				--self.object:setvelocity({x = vel.x * 0.8, y = -0.01, z = vel.x * 0.8})
				self.object:setacceleration({x = 0, y = -0.2, z = 0})
				return
			end
		end
	end





	--handle falling
	if vel.y < 0
	then
		--if falling
		self.falling_timer = self.falling_timer + 1
		if self.falling_timer < 10 and self.life_timer > 10
		then
			local acc = {x = vel.x * -vel.y, y = -9, z = vel.z * -vel.y}
			self.object:setacceleration(acc)
		end
	elseif self.falling_timer > 0
	then
		--bounce
		self.falling_timer = 0

		local bounce_height = vector.length(vel) * 0.7

		--chance to explode on bounce
		if self.fuse
		then
			self.fuse = self.fuse - bounce_height * math.random()
		elseif bounce_height > 2 and math.random() > 0.9
		then
			self:start_fuse(20 * math.random())
		end
		vel = {
			x = vel.x * 0.99,
			y = vector.length(vel) * 0.5,
			z = vel.z * 0.99
			}
		self.object:setvelocity(vel)

		minetest.sound_play(
			"gunpowder_barrels_bump",
			{
			object = self.object,
			gain = bounce_height * 0.025,
			pitch = 0.5,
			max_hear_distance = 32,
			})

	end
	if self.falling_timer <= 0 or self.falling_timer >= 10
	then
		self.object:setacceleration({x = 0, y = -9, z = 0})
		if vel.y == 0
		then
			--applying friction
			vel = vector.multiply(vel, 0.99)
			self.object:setvelocity(vel)
		end
	end
end


--kick barrel, doesn't light fuse
--fuse has a chance to be lit when bouncing though
entity_definition.on_rightclick = function(self, clicker)
	if clicker
	then
		local clickerpos = clicker:get_pos()
		local kick = vector.subtract(self.object:get_pos(), clickerpos)
		kick.y = 0
		kick = vector.normalize(kick)
		kick = vector.multiply(kick, 5)
		self.object:setvelocity(kick)
	end
end


entity_definition.on_punch = function(self)
	--light fuse for 5 to 10 seconds
	if not self.fuse
	then
		self:start_fuse(math.random() * 100 + 100)
	else
		self.fuse = self.fuse - math.random() * 10
	end
end


minetest.register_entity("gunpowder_barrels:barrel_entity", entity_definition)