mod-sneeker/tnt_function.lua

--[[ From TNT

License of source code
----------------------

The MIT License (MIT)
Copyright (C) 2014-2016 PilzAdam
Copyright (C) 2014-2016 ShadowNinja
Copyright (C) 2016 sofar (sofar@foo-projects.org)
Copyright (C) 2014-2016 Various Minetest developers and contributors

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substantial portions of the Software.

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INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
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OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

For more details:
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===================================

Licenses of media
-----------------

Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)
Copyright (C) 2014-2016 BlockMen
Copyright (C) 2014-2016 ShadowNinja
Copyright (C) 2015-2016 Wuzzy
Copyright (C) 2016 sofar (sofar@foo-projects.org)
Copyright (C) 2018 paramat

You are free to:
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rights may limit how you use the material.

For more details:
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====================================================

CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
for audio files (found in sounds folder)
TumeniNodes
steveygos93
theneedle.tv
frankelmedico

No Copyright

The person who associated a work with this deed has dedicated the work to the public domain
by waiving all of his or her rights to the work worldwide under copyright law, including all
related and neighboring rights, to the extent allowed by law.

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]]


local cid_data = {}
local radius = tonumber(core.settings:get("tnt_radius") or 3)
local large_radius = 5
local loss_prob = {
	["default:cobble"] = 3,
	["default:dirt"] = 4,
}
core.after(0, function()
	for name, def in pairs(core.registered_nodes) do
		cid_data[core.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 = core.add_item(drop_pos, item)
			if obj then
				obj:get_luaentity().collect = true
				obj:set_acceleration({x=0, y=-10, z=0})
				obj:set_velocity({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 function is_protected(pos, name) return core.is_protected(pos, name) end
if core.global_exists("simple_protection") and simple_protection.can_access then
	is_protected = function(pos, name)
		local s_protect_name = name
		-- simple_protection ignores names with empty strings
		if s_protect_name == "" then
			s_protect_name = " "
		end

		return core.is_protected(pos, name) or not simple_protection.can_access(pos, s_protect_name)
	end
end

local function destroy(drops, pos, cid)
	if is_protected(pos, "") then
		return
	end
	local def = cid_data[cid]
	if def and def.on_blast then
		def.on_blast(vector.new(pos), 1)
		return
	end
	core.remove_node(pos)
	if def then
		local node_drops = core.get_node_drops(def.name, "")
		for _, item in ipairs(node_drops) do
			add_drop(drops, item)
		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 = core.get_objects_inside_radius(pos, radius)
	for _, obj in pairs(objs) do
		local obj_pos = obj:get_pos()
		local obj_vel = obj:get_velocity()
		local dist = math.max(1, vector.distance(pos, obj_pos))

		if obj_vel ~= nil then
			obj:set_velocity(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)
	core.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 = "sneeker_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 = core.get_content_id("air")
	local c_tnt = nil
	if core.settings:get_bool("enable_tnt", false) then
		c_tnt = core.get_content_id("tnt:tnt")
	end

	local c_tnt_burning = core.get_content_id("tnt:tnt_burning")
	local c_gunpowder = core.get_content_id("tnt:gunpowder")
	local c_gunpowder_burning = core.get_content_id("tnt:gunpowder_burning")
	local c_boom = core.get_content_id("tnt:boom")

	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_boom then
				destroy(drops, p, cid)
			end
		end
		vi = vi + 1
	end
	end
	end

	return drops
end

function sneeker.boom(pos, large)
	if not pos then return end

	local radius = radius
	if large then
		radius = large_radius
	end
	core.sound_play("sneeker_explode", {pos=pos, gain=1.5, max_hear_distance=2*64})
	core.set_node(pos, {name="tnt:boom"})
	core.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)
	core.remove_node(pos)
end