MineClone2/mods/CORE/mcl_explosions/init.lua
Elias Åström b4ea2afe77 Add tnt_knockback flag for entities
When set to true, entities will be knocked back when affected by TNT
explosions.  Also ignore '__builtin:item' entities to reduce lag, and
replace tabs with spaces in 'mcl_explosions/init.lua'.
2020-04-19 13:08:36 +02:00

414 lines
13 KiB
Lua

--[[ .__ .__
____ ___ _________ | | ____ _____|__| ____ ____ ______
_/ __ \\ \/ /\____ \| | / _ \/ ___/ |/ _ \ / \ / ___/
\ ___/ > < | |_> > |_( <_> )___ \| ( <_> ) | \\___ \
\___ >__/\_ \| __/|____/\____/____ >__|\____/|___| /____ >
\/ \/|__| \/ \/ \/
Explosion API mod for Minetest (adapted to MineClone 2)
This mod is based on the Minetest explosion API mod, but has been changed
to have the same explosion mechanics as Minecraft and work with MineClone.
The computation-intensive parts of the mod has been optimized to allow for
larger explosions and faster world updating.
This mod was created by Elias Astrom <ryvnf@riseup.net> and is released
under the LGPLv2.1 license.
--]]
mcl_explosions = {}
-- Saved sphere explosion shapes for various radiuses
local sphere_shapes = {}
-- Saved node definitions in table using cid-keys for faster look-up.
local node_br = {}
local node_on_blast = {}
local AIR_CID = minetest.get_content_id('air')
-- The step length for the rays (Minecraft uses 0.3)
local STEP_LENGTH = 0.3
-- How many rays to compute entity exposure to explosion
local N_EXPOSURE_RAYS = 16
minetest.after(0, function()
-- Store blast resistance values by content ids to improve performance.
for name, def in pairs(minetest.registered_nodes) do
node_br[minetest.get_content_id(name)] = def._mcl_blast_resistance or 0
node_on_blast[minetest.get_content_id(name)] = def.on_blast
end
end)
-- Compute the rays which make up a sphere with radius. Returns a list of rays
-- which can be used to trace explosions. This function is not efficient
-- (especially for larger radiuses), so the generated rays for various radiuses
-- should be cached and reused.
--
-- Should be possible to improve by using a midpoint circle algorithm multiple
-- times to create the sphere, currently uses more of a brute-force approach.
local function compute_sphere_rays(radius)
local rays = {}
local sphere = {}
for y = -radius, radius do
for z = -radius, radius do
for x = -radius, 0, 1 do
local d = x * x + y * y + z * z
if d <= radius * radius then
local pos = { x = x, y = y, z = z }
sphere[minetest.hash_node_position(pos)] = pos
break
end
end
end
end
for y = -radius, radius do
for z = -radius, radius do
for x = radius, 0, -1 do
local d = x * x + y * y + z * z
if d <= radius * radius then
local pos = { x = x, y = y, z = z }
sphere[minetest.hash_node_position(pos)] = pos
break
end
end
end
end
for x = -radius, radius do
for z = -radius, radius do
for y = -radius, 0, 1 do
local d = x * x + y * y + z * z
if d <= radius * radius then
local pos = { x = x, y = y, z = z }
sphere[minetest.hash_node_position(pos)] = pos
break
end
end
end
end
for x = -radius, radius do
for z = -radius, radius do
for y = radius, 0, -1 do
local d = x * x + y * y + z * z
if d <= radius * radius then
local pos = { x = x, y = y, z = z }
sphere[minetest.hash_node_position(pos)] = pos
break
end
end
end
end
for x = -radius, radius do
for y = -radius, radius do
for z = -radius, 0, 1 do
local d = x * x + y * y + z * z
if d <= radius * radius then
local pos = { x = x, y = y, z = z }
sphere[minetest.hash_node_position(pos)] = pos
break
end
end
end
end
for x = -radius, radius do
for y = -radius, radius do
for z = radius, 0, -1 do
local d = x * x + y * y + z * z
if d <= radius * radius then
local pos = { x = x, y = y, z = z }
sphere[minetest.hash_node_position(pos)] = pos
break
end
end
end
end
for _, pos in pairs(sphere) do
rays[#rays + 1] = vector.normalize(pos)
end
return rays
end
-- Add particles from explosion
--
-- Parameters:
-- pos - The position of the explosion
-- radius - The radius of the explosion
local function add_particles(pos, radius)
minetest.add_particlespawner({
amount = 64,
time = 0.125,
minpos = pos,
maxpos = pos,
minvel = {x = -radius, y = -radius, z = -radius},
maxvel = {x = radius, y = radius, z = radius},
minacc = vector.new(),
maxacc = vector.new(),
minexptime = 0.5,
maxexptime = 1.0,
minsize = radius * 0.5,
maxsize = radius * 1.0,
texture = "tnt_smoke.png",
})
end
-- Get position from hash. This should be identical to
-- 'minetest.get_position_from_hash' but is used in case the hashing function
-- would change.
local function get_position_from_hash(hash)
local pos = {}
pos.x = (hash % 65536) - 32768
hash = math.floor(hash / 65536)
pos.y = (hash % 65536) - 32768
hash = math.floor(hash / 65536)
pos.z = (hash % 65536) - 32768
return pos
end
-- Traces the rays of an explosion, and updates the environment.
--
-- Parameters:
-- pos - Where the rays in the explosion should start from
-- strength - The strength of each ray
-- raydirs - The directions for each ray
-- radius - The maximum distance each ray will go
-- drop_chance - The chance that destroyed nodes will drop their items
--
-- Note that this function has been optimized, it contains code which has been
-- inlined to avoid function calls and unnecessary table creation. This was
-- measured to give a significant performance increase.
local function trace_explode(pos, strength, raydirs, radius, drop_chance)
local vm = minetest.get_voxel_manip()
local emin, emax = vm:read_from_map(vector.subtract(pos, radius),
vector.add(pos, radius))
local emin_x = emin.x
local emin_y = emin.y
local emin_z = emin.z
local ystride = (emax.x - emin_x + 1)
local zstride = ystride * (emax.y - emin_y + 1)
local pos_x = pos.x
local pos_y = pos.y
local pos_z = pos.z
local area = VoxelArea:new {
MinEdge = emin,
MaxEdge = emax
}
local data = vm:get_data()
local destroy = {}
-- Trace rays for environment destruction
for i = 1, #raydirs do
local rpos_x = pos.x
local rpos_y = pos.y
local rpos_z = pos.z
local rdir_x = raydirs[i].x
local rdir_y = raydirs[i].y
local rdir_z = raydirs[i].z
local rstr = (0.7 + math.random() * 0.6) * strength
for r = 0, math.ceil(radius * (1.0 / STEP_LENGTH)) do
local npos_x = math.floor(rpos_x + 0.5)
local npos_y = math.floor(rpos_y + 0.5)
local npos_z = math.floor(rpos_z + 0.5)
local idx = (npos_z - emin_z) * zstride + (npos_y - emin_y) * ystride +
npos_x - emin_x + 1
local cid = data[idx]
local br = node_br[cid]
local hash = (npos_z + 32768) * 65536 * 65536 +
(npos_y + 32768) * 65536 +
npos_x + 32768
rpos_x = rpos_x + STEP_LENGTH * rdir_x
rpos_y = rpos_y + STEP_LENGTH * rdir_y
rpos_z = rpos_z + STEP_LENGTH * rdir_z
rstr = rstr - 0.75 * STEP_LENGTH - (br + 0.3) * STEP_LENGTH
if rstr <= 0 then
break
end
if cid ~= AIR_CID then
destroy[hash] = idx
end
end
end
-- Entities in radius of explosion
local punch_radius = 2 * strength
local objs = minetest.get_objects_inside_radius(pos, punch_radius)
-- Trace rays for entity damage
for _, obj in pairs(objs) do
local ent = obj:get_luaentity()
-- Ignore items to lower lag
if obj:is_player() or (ent and ent.name ~= '__builtin.item') then
local opos = obj:get_pos()
local collisionbox = nil
if obj:is_player() then
collisionbox = { -0.3, 0.0, -0.3, 0.3, 1.77, 0.3 }
elseif ent.name then
local def = minetest.registered_entities[ent.name]
collisionbox = def.collisionbox
end
if collisionbox then
-- Create rays from random points in the collision box
local x1 = collisionbox[1] * 2
local y1 = collisionbox[2] * 2
local z1 = collisionbox[3] * 2
local x2 = collisionbox[4] * 2
local y2 = collisionbox[5] * 2
local z2 = collisionbox[6] * 2
local x_len = math.abs(x2 - x1)
local y_len = math.abs(y2 - y1)
local z_len = math.abs(z2 - z1)
-- Move object position to the center of its bounding box
opos.x = opos.x + x1 + x2
opos.y = opos.y + y1 + y2
opos.z = opos.z + z1 + z2
-- Count number of rays from collision box which are unobstructed
local count = N_EXPOSURE_RAYS
for i = 1, N_EXPOSURE_RAYS do
local rpos_x = opos.x + math.random() * x_len - x_len / 2
local rpos_y = opos.y + math.random() * y_len - y_len / 2
local rpos_z = opos.z + math.random() * z_len - z_len / 2
local rdir_x = pos.x - rpos_x
local rdir_y = pos.y - rpos_y
local rdir_z = pos.z - rpos_z
local rdir_len = math.hypot(rdir_x, math.hypot(rdir_y, rdir_z))
rdir_x = rdir_x / rdir_len
rdir_y = rdir_y / rdir_len
rdir_z = rdir_z / rdir_len
for i=0, rdir_len / STEP_LENGTH do
rpos_x = rpos_x + rdir_x * STEP_LENGTH
rpos_y = rpos_y + rdir_y * STEP_LENGTH
rpos_z = rpos_z + rdir_z * STEP_LENGTH
local npos_x = math.floor(rpos_x + 0.5)
local npos_y = math.floor(rpos_y + 0.5)
local npos_z = math.floor(rpos_z + 0.5)
local idx = (npos_z - emin_z) * zstride + (npos_y - emin_y) * ystride +
npos_x - emin_x + 1
local cid = data[idx]
local br = node_br[cid]
if br ~= 0 then
count = count - 1
break
end
end
end
-- Punch entity with damage depending on explosion exposure and
-- distance to explosion
local exposure = count / N_EXPOSURE_RAYS
local punch_vec = vector.subtract(opos, pos)
local punch_dir = vector.normalize(punch_vec)
local impact = (1 - vector.length(punch_vec) / punch_radius) * exposure
if impact < 0 then
impact = 0
end
local damage = math.floor((impact * impact + impact) * 7 * strength + 1)
obj:punch(obj, 10, { damage_groups = { full_punch_interval = 1,
fleshy = damage, knockback = impact * 20.0 } }, punch_dir)
if obj:is_player() then
obj:add_player_velocity(vector.multiply(punch_dir, impact * 20))
elseif ent.tnt_knockback then
obj:add_velocity(vector.multiply(punch_dir, impact * 20))
end
end
end
end
-- Remove destroyed blocks and drop items
for hash, idx in pairs(destroy) do
local do_drop = math.random() <= drop_chance
local on_blast = node_on_blast[data[idx]]
local remove = true
if do_drop or on_blast ~= nil then
local npos = get_position_from_hash(hash)
if on_blast ~= nil then
remove = on_blast(npos, 1.0)
else
local name = minetest.get_name_from_content_id(data[idx])
local drop = minetest.get_node_drops(name, "")
for _, item in ipairs(drop) do
if type(item) == "string" then
minetest.add_item(npos, item)
end
end
end
end
if remove then
data[idx] = AIR_CID
end
end
-- Log explosion
minetest.log('action', 'Explosion at ' .. minetest.pos_to_string(pos) ..
' with strength ' .. strength .. ' and radius ' .. radius)
-- Update environment
vm:set_data(data)
vm:write_to_map(data)
vm:update_liquids()
end
-- Create an explosion with strength at pos.
--
-- Parameters:
-- pos - The position where the explosion originates from
-- strength - The blast strength of the explosion (a TNT explosion uses 4)
-- info - Table containing information about explosion.
--
-- Values in info:
-- drop_chance - If specified becomes the drop chance of all nodes in the
-- explosion (defaults to 1.0 / strength)
-- no_sound - If true then the explosion will not play a sound
-- no_particle - If true then the explosion will not create particles
function mcl_explosions.explode(pos, strength, info)
-- The maximum blast radius (in the air)
local radius = math.ceil(1.3 * strength / (0.3 * 0.75) * 0.3)
if not sphere_shapes[radius] then
sphere_shapes[radius] = compute_sphere_rays(radius)
end
shape = sphere_shapes[radius]
trace_explode(pos, strength, shape, radius, (info and info.drop_chance) or 1 / strength)
if not (info and info.no_sound) then
add_particles(pos, radius)
end
if not (info and info.no_particle) then
minetest.sound_play("tnt_explode", {
pos = pos, gain = 1.0,
max_hear_distance = strength * 16
}, true)
end
end