DigWorks/mods/CORE/mcl_particles/init.lua

local vector = vector
local table = table

local hash_node_position = minetest.hash_node_position
local add_particlespawner = minetest.add_particlespawner
local delete_particlespawner = minetest.delete_particlespawner

local ipairs = ipairs

mcl_particles = {}

-- Table of particlespawner IDs on a per-node hash basis
-- Keys: node position hashes
-- Values: Tables of particlespawner IDs (each node pos can have an arbitrary number of particlespawners)
local particle_nodes = {}

-- Node particles can be disabled via setting
local node_particles_allowed = minetest.settings:get("mcl_node_particles") or "none"

local levels = {
	high = 3,
	medium = 2,
	low = 1,
	none = 0,
}

allowed_level = levels[node_particles_allowed]
if not allowed_level then
	allowed_level = levels["none"]
end


-- Add a particlespawner that is assigned to a given node position.
-- * pos: Node positon. MUST use integer values!
-- * particlespawner_definition: definition for minetest.add_particlespawner
-- * level: detail level of particles. "high", "medium", "low" or "none". High detail levels are for
-- CPU-demanding particles, like smoke of fire (which occurs frequently)
-- NOTE: All particlespawners are automatically removed on shutdown.
-- Returns particlespawner ID on succcess and nil on failure
function mcl_particles.add_node_particlespawner(pos, particlespawner_definition, level)
	if allowed_level == 0 or levels[level] > allowed_level then
		return
	end
	local poshash = hash_node_position(pos)
	if not poshash then
		return
	end
	local id = add_particlespawner(particlespawner_definition)
	if id == -1 then
		return
	end
	if not particle_nodes[poshash] then
		particle_nodes[poshash] = {}
	end
	table.insert(particle_nodes[poshash], id)
	return id
end

local add_node_particlespawner = mcl_particles.add_node_particlespawner

-- Deletes all particlespawners that are assigned to a node position.
-- If no particlespawners exist for this position, nothing happens.
-- pos: Node positon. MUST use integer values!
-- Returns true if particlespawner could be removed and false if not
function mcl_particles.delete_node_particlespawners(pos)
	if allowed_level == 0 then
		return false
	end
	local poshash = hash_node_position(pos)
	local ids = particle_nodes[poshash]
	if ids then
		for i=1, #ids do
			delete_particlespawner(ids[i])
		end
		particle_nodes[poshash] = nil
		return true
	end
	return false
end

-- 3 exptime variants because the animation is not tied to particle expiration time.
-- 3 colorized variants to imitate minecraft's
local smoke_pdef_cached = {}

function mcl_particles.spawn_smoke(pos, name, smoke_pdef_base)
	local new_minpos = vector.add(pos, smoke_pdef_base.minrelpos)
	local new_maxpos = vector.add(pos, smoke_pdef_base.maxrelpos)

	-- populate the cache
	if smoke_pdef_cached[name] then
		for i, smoke_pdef in ipairs(smoke_pdef_cached[name]) do
			smoke_pdef.minpos = new_minpos
			smoke_pdef.maxpos = new_maxpos
			add_node_particlespawner(pos, smoke_pdef, "high")
		end
		-- cache already populated
	else
		smoke_pdef_cached[name] = {}

		local smoke_pdef = table.copy(smoke_pdef_base)
		smoke_pdef.amount = smoke_pdef_base.amount / 9
		smoke_pdef.time = 0
		smoke_pdef.animation = {
			type = "vertical_frames",
			aspect_w = 8,
			aspect_h = 8,
			-- length = 3 exptime variants
		}
		smoke_pdef.collisiondetection = true
		smoke_pdef.minpos = new_minpos
		smoke_pdef.maxpos = new_maxpos

		-- the last frame plays for 1/8 * N seconds, so we can take advantage of it
		-- to have varying exptime for each variant.
		local exptimes = { 0.175, 0.375, 1.0 }
		local colorizes = { "199", "209", "243" } -- round(78%, 82%, 90% of 256) - 1

		for _,exptime in ipairs(exptimes) do
			for _,colorize in ipairs(colorizes) do
				smoke_pdef.maxexptime = exptime * smoke_pdef_base.maxexptime
				smoke_pdef.animation.length = exptime + 0.1
				-- minexptime must be set such that the last frame is actully rendered,
				-- even if its very short. Larger exptime -> larger range
				smoke_pdef.minexptime = math.min(exptime, (7.0/8.0 * (exptime + 0.1) + 0.1))
				smoke_pdef.texture = "mcl_particles_smoke_anim.png^[colorize:#000000:" ..colorize
				add_node_particlespawner(pos, smoke_pdef, "high")
				table.insert(smoke_pdef_cached[name], table.copy(smoke_pdef))
			end
		end
	end
end