New, fancier portal particle effects

mod.conf

@@ -1,4 +1,4 @@
 name = nc_skyrealm
 depends = nc_api_all, nc_terrain, nc_sponge, nc_tree, nc_lode, nc_lux, nc_concrete, nc_fire
 optional_depends = nc_guide
-min_minetest_version = 5.3
+min_minetest_version = 5.8

portal.lua

@@ -1,8 +1,8 @@
 -- LUALOCALS < ---------------------------------------------------------
-local ipairs, math, minetest, nodecore, pairs, vector
-    = ipairs, math, minetest, nodecore, pairs, vector
-local math_random
-    = math.random
+local ipairs, math, minetest, nodecore, pairs, tostring, vector
+    = ipairs, math, minetest, nodecore, pairs, tostring, vector
+local math_ceil, math_cos, math_pi, math_random
+    = math.ceil, math.cos, math.pi, math.random
 -- LUALOCALS > ---------------------------------------------------------
 
 local modname = minetest.get_current_modname()
@@ -43,8 +43,19 @@ local function portalemerge(pos, ipos)
 	end
 end
 
+local w = 16
+local frames = 32
+local base = nodecore.tmod(modname .. "_particle.png"):resize(w, w)
+local txr = nodecore.tmod:combine(w, frames * w)
+for i = 0, frames - 1 do
+	local o = math_ceil((1 - math_cos(i * math_pi * 2 / frames)) * 128)
+	if o > 255 then o = 255 end
+	txr = txr:layer(0, w * i, base:opacity(o))
+end
+txr = tostring(txr)
+
 local function portaltick(pos, att, stack)
-	if api.in_sky_realm(pos) then return end
+	local inert = stack or att or api.in_sky_realm(pos)
 	local assign = getassign(stack and stack:get_meta()
 		or minetest.get_meta(pos), nil, true)
 	if assign then
@@ -61,16 +72,41 @@ local function portaltick(pos, att, stack)
 	end
 	return minetest.add_particlespawner({
 			time = 1,
-			amount = 50,
-			minpos = pos,
-			maxpos = pos,
-			minacc = {x = -0.2, y = -0.2, z = -0.2},
-			maxacc = {x = 0.2, y = 0.2, z = 0.2},
-			minexptime = 1,
-			maxexptime = 5,
-			minsize = 0.2,
-			maxsize = 1,
-			texture = modname .. "_particle.png",
+			amount = inert and 50 or 100,
+			exptime = {
+				min = 1,
+				max = 5,
+				bias = 1
+			},
+			size = {
+				min = 0.2,
+				max = inert and 1 or 2
+			},
+			minvel = vector.new(-0.1, -0.1, -0.1),
+			maxvel = vector.new(0.1, 0.1, 0.1),
+			minacc = vector.new(-0.1, -0.1, -0.1),
+			maxacc = vector.new(0.1, 0.1, 0.1),
+			texture = txr,
+			animation = {
+				type = "vertical_frames",
+				aspect_w = 16,
+				length = -1
+			},
+			pos = pos,
+			radius = {
+				min = 1,
+				max = inert and 2 or 8,
+				bias = 1
+			},
+			attract = (not inert) and {
+				kind = "point",
+				strength = {
+					min = 0.25,
+					max = 2,
+					bias = 1
+				},
+				origin = pos
+			} or nil,
 			collisiondetection = true,
 			collision_removal = true,
 			attached = att