From 1d5c11f68391caad31bffbe474b56160cd7af2f8 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Elias=20=C3=85str=C3=B6m?= Date: Wed, 15 Apr 2020 14:15:07 +0200 Subject: [PATCH] Add mcl_explosions for ray traced explosions Code has been adapted from the Minetest explosions API mod to have Minecraft-like explosion mechanics and work with MineClone 2. --- mods/CORE/mcl_explosions/description.txt | 1 + mods/CORE/mcl_explosions/init.lua | 266 +++++++++++++++++++++++ 2 files changed, 267 insertions(+) create mode 100644 mods/CORE/mcl_explosions/description.txt create mode 100644 mods/CORE/mcl_explosions/init.lua diff --git a/mods/CORE/mcl_explosions/description.txt b/mods/CORE/mcl_explosions/description.txt new file mode 100644 index 0000000000..a9d5288b55 --- /dev/null +++ b/mods/CORE/mcl_explosions/description.txt @@ -0,0 +1 @@ +This mod adds a common API to create explosions. diff --git a/mods/CORE/mcl_explosions/init.lua b/mods/CORE/mcl_explosions/init.lua new file mode 100644 index 0000000000..6909bdc6a6 --- /dev/null +++ b/mods/CORE/mcl_explosions/init.lua @@ -0,0 +1,266 @@ +--[[ .__ .__ + ____ ___ _________ | | ____ _____|__| ____ ____ ______ + _/ __ \\ \/ /\____ \| | / _ \/ ___/ |/ _ \ / \ / ___/ + \ ___/ > < | |_> > |_( <_> )___ \| ( <_> ) | \\___ \ + \___ >__/\_ \| __/|____/\____/____ >__|\____/|___| /____ > + \/ \/|__| \/ \/ \/ + + 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 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 AIR_CID = minetest.get_content_id('air') + +-- The step length for the rays (Minecraft uses 0.3) +local STEP_LENGTH = 0.3 + +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 + 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 + +-- 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 - Chance that destroy nodes drop their items +-- (becomes '1.0 / strength' if unspecified) +-- +-- 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 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 + + if drop_chance == nil then + drop_chance = 1 / strength + end + + -- Remove destroyed blocks and drop items + for hash, idx in pairs(destroy) do + if math.random() <= drop_chance then + 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(get_position_from_hash(hash), item) + end + end + end + data[idx] = AIR_CID + 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) +function mcl_explosions.explode(pos, strength) + -- 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) +end