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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DEALINGS IN THE SOFTWARE.

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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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====================================================

CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
for audio files (found in sounds folder)
TumeniNodes
steveygos93
theneedle.tv
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by waiving all of his or her rights to the work worldwide under copyright law, including all
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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 destroy(drops, pos, cid)
	if core.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